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Project Specific Discussions => Dynamic Processors => Topic started by: mnats on September 05, 2014, 12:00:39 AM

Title: [BUILD] FET/500 Official Support Thread
Post by: mnats on September 05, 2014, 12:00:39 AM
FET/500 page, linked searchable documentation  (http://mnats.net/fet500.html)
Calibration video added! (http://mnats.net/fet500.html#calibration)
General troubleshooting page (http://mnats.net/1176_FAQ.html)
Sub-site for boards and kits (http://www.hairballaudio.com/FET500/)

Please post support questions not covered in the documentation linked above to this thread.

As data is collected I will either update the page(s) linked above or link to the forum posts that cover common build issues or questions from the first or second posts of this thread.

Please keep any commercial discussion or general comments in the White Market thread (http://groupdiy.com/index.php?topic=28923.0). Thank you.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on September 05, 2014, 12:01:05 AM
Reserved
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Cgaines on September 25, 2014, 11:55:58 PM
Hello,

I just finished building my hairball fet500 and everything went great! I thought the instructions were clear and straight forward. I do have a little problem that I can't wrap my head around. My VU meter doesn't calibrate like the videos. The gain reduction seems fine, as well as everything else. All of the voltages line up and everything. The problem is, when I adjust VR1 and VR2 I can't get the peak lie and second, -10 light to light up. I went back and recalibrated everything a couple of times and one time I accidentally had the ratio set to 4:1. I was able to get the -10 light to come on that time, but no peak light. Any thoughts on what could be going on?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 26, 2014, 12:03:36 AM
Hello,

I just finished building my hairball fet500 and everything went great! I thought the instructions were clear and straight forward. I do have a little problem that I can't wrap my head around. My VU meter doesn't calibrate like the videos. The gain reduction seems fine, as well as everything else. All of the voltages line up and everything. The problem is, when I adjust VR1 and VR2 I can't get the peak lie and second, -10 light to light up. I went back and recalibrated everything a couple of times and one time I accidentally had the ratio set to 4:1. I was able to get the -10 light to come on that time, but no peak light. Any thoughts on what could be going on?

You need to double check the resistors on the meter PCB.  We included a few extra ones in the kit.  There was an 82K in the kit in error (don't use it), and a 110K used only if building the Rev F.

Also, confirm your Qbias is adjusted correctly.

Mike

ps- It's not a "Hairball" FET/500.  MNATs did all of the circuit design. We were just part of it.   ;)
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Cgaines on September 26, 2014, 12:16:55 AM
My apologies for the mixup! Much respect to the both of you then. I do feel like I have the Qbias adjusted correctly though. I got all of the final voltages you did in the video. The only difference is yours pinched off at over 8 volts and mine only went up to five. It does look like I have an 82k resistor installed in R206. Is that the one? What value should it be?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 26, 2014, 12:20:29 AM
My apologies for the mixup! Much respect to the both of you then. I do feel like I have the Qbias adjusted correctly though. I got all of the final voltages you did in the video. The only difference is yours pinched off at over 8 volts and mine only went up to five. It does look like I have an 82k resistor installed in R206. Is that the one? What value should it be?

R203 is the resistor in question.  R203 is 22K for Rev A/D and 110K for Rev F.

http://www.hairballaudio.com/buildmaps/meter500/

I'd look over the whole meter PCB with the build checklist again.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 26, 2014, 12:25:58 AM
Also cross check against your Revisions "Overlay, Schematic, Bill of Materials" on the MNATs site.

http://mnats.net/fet500.html

Possible we made an error on the stuffing map, however there have been a number of completed successful builds.  You either have a misplaced part on the meter or a calibration issue.  Keep hunting around!

Mike

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Cgaines on September 26, 2014, 12:40:48 AM
Well I checked all of the resistor color bands and they all match up. Testing each of them I only found a couple of issues. R227 is a 10k and it only reads at about 5k. R223 is a 3.4k (even though my color bands show it as a 3480) and it reads at about 2.6. Other than that, that's what I get. Did the lower pinch off voltage on the FET not matter when setting the Q bias?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Cgaines on September 26, 2014, 12:43:18 AM
Is there a way to get the trim pots swapped? One is supposed to be a 10k the other a 1k. They are labeled the same but I think before i installed them they tested correct on my DMM.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 26, 2014, 12:48:00 AM
Is there a way to get the trim pots swapped? One is supposed to be a 10k the other a 1k. They are labeled the same but I think before i installed them they tested correct on my DMM.

The should not be labeled the same.  One should have a "102" for 1K and the other "103" for 10K.  It's marked on the side somewhere.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 26, 2014, 12:49:23 AM
Well I checked all of the resistor color bands and they all match up. Testing each of them I only found a couple of issues. R227 is a 10k and it only reads at about 5k. R223 is a 3.4k (even though my color bands show it as a 3480) and it reads at about 2.6. Other than that, that's what I get. Did the lower pinch off voltage on the FET not matter when setting the Q bias?

If there are parallel resistances that'll mess up the ohm reading.  no worries.

Impossible to know about the pinch off voltage, there are about 10 different variables.  Probably not the issue.


Mike

PS- I'm traveling right now and have very limited internet access.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 26, 2014, 12:50:23 AM
Is there a way to get the trim pots swapped? One is supposed to be a 10k the other a 1k. They are labeled the same but I think before i installed them they tested correct on my DMM.

Make sure you got a 1K and a 10K and that they are not swapped.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Cgaines on September 26, 2014, 12:56:56 AM
Is there a way to get the trim pots swapped? One is supposed to be a 10k the other a 1k. They are labeled the same but I think before i installed them they tested correct on my DMM.

The should not be labeled the same.  One should have a "102" for 1K and the other "103" for 10K.  It's marked on the side somewhere.



Well sh*t.. there's my problem. I have those in the wrong place. That's gonna be fun getting out... Thanks for the help! It's always nice to bounce off ideas! Safe travels. And again, thanks for helping. Even when you don't have to.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: ericyoshino on October 03, 2014, 06:45:31 PM
Hey! How you all doing?

Eric from Brazil here! Got a pair of hairball kits for the MNATS FET500.

Just finished the first. I can't yet go to calibration process because of two issues:

- There are two components I can't identify. Looks like a tantalum capacitor, one is labelled X10 BAW the other X10 ZYJ. I don't know which one to use on R219.

- And the other problem is that both my hairball kits are missing 1uF eletrolytic capacitor C017.

 Can someone help me out  :'(

Thanks in advance
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 04, 2014, 10:55:33 PM
Hey! How you all doing?

Eric from Brazil here! Got a pair of hairball kits for the MNATS FET500.

Just finished the first. I can't yet go to calibration process because of two issues:

- There are two components I can't identify. Looks like a tantalum capacitor, one is labelled X10 BAW the other X10 ZYJ. I don't know which one to use on R219.

- And the other problem is that both my hairball kits are missing 1uF eletrolytic capacitor C017.

 Can someone help me out  :'(

Thanks in advance

R219 is a resettable fuse.  See the images in the build guide. 

I'm not sure what parts you're referring to.  Maybe post an image?

The D kits were short a 1uF capacitor I think.  We can send you one.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: ericyoshino on October 06, 2014, 02:07:58 AM
Hey! How you all doing?

Eric from Brazil here! Got a pair of hairball kits for the MNATS FET500.

Just finished the first. I can't yet go to calibration process because of two issues:

- There are two components I can't identify. Looks like a tantalum capacitor, one is labelled X10 BAW the other X10 ZYJ. I don't know which one to use on R219.

- And the other problem is that both my hairball kits are missing 1uF eletrolytic capacitor C017.

 Can someone help me out  :'(

Thanks in advance

R219 is a resettable fuse.  See the images in the build guide. 

I'm not sure what parts you're referring to.  Maybe post an image?

The D kits were short a 1uF capacitor I think.  We can send you one.

Mike

Here it is! There are two of this in each kit, I don't know if they are the same. Which one should I use in R219?

https://www.dropbox.com/s/5cywlddd8b9n45h/IMG_1588.JPG

About the C017 1uF capacitor, it depends if it will change the sound of the compressor. If not, I can find a replacement around here, if it does change I'd rather wait for you to send it to me.

Thanks a lot! :D
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Dr Gris on October 06, 2014, 02:15:47 PM
Can't find a C017 but a C17. It's an electrolytic cap. Maybe I'm missing something...

Looking at the D/500 FET Limiter schematic and it says C17 is 22uF but that must be wrong and the BOM is right. Or maybe my eyes are tired...

Saving up for some of these babies, what a fantastic work Mako and you guys have done!!!

Cheers
//Magnus
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: ericyoshino on October 10, 2014, 06:20:37 PM
Can't find a C017 but a C17. It's an electrolytic cap. Maybe I'm missing something...

Looking at the D/500 FET Limiter schematic and it says C17 is 22uF but that must be wrong and the BOM is right. Or maybe my eyes are tired...

Saving up for some of these babies, what a fantastic work Mako and you guys have done!!!

Cheers
//Magnus

They are the same, C017 and C17.

The schematic indeed says its 22uF, but the original 1176 project uses a 1uF as indicated in Hairball's Build Guide:

"On the Rev D we’ve subbed C17 from a 22uF to a 1uF to match the original schematic"

I just need to know if this capacitor will affect the sound of the compressor. If not I can buy it here in Brazil from a chinese manufacturer. If it does change the sound, I'd rather wait Hairball to send them to me.

Thanks :) cheers!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 10, 2014, 07:50:24 PM
Can't find a C017 but a C17. It's an electrolytic cap. Maybe I'm missing something...

Looking at the D/500 FET Limiter schematic and it says C17 is 22uF but that must be wrong and the BOM is right. Or maybe my eyes are tired...

Saving up for some of these babies, what a fantastic work Mako and you guys have done!!!

Cheers
//Magnus

They are the same, C017 and C17.

The schematic indeed says its 22uF, but the original 1176 project uses a 1uF as indicated in Hairball's Build Guide:

"On the Rev D we’ve subbed C17 from a 22uF to a 1uF to match the original schematic"

I just need to know if this capacitor will affect the sound of the compressor. If not I can buy it here in Brazil from a chinese manufacturer. If it does change the sound, I'd rather wait Hairball to send them to me.

Thanks :) cheers!


It's just a DC blocker.  1-22uF is fine.  We can send one to you if you like.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 10, 2014, 07:51:27 PM
Those fuses in the picture are the same.  Looks like you got two instead of one.

The labeling on them is just build date and location info.  Use either one.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: ericyoshino on October 14, 2014, 12:13:23 AM
Those fuses in the picture are the same.  Looks like you got two instead of one.

The labeling on them is just build date and location info.  Use either one.

Thanks a lot! Appreciate it
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: rockprocess on October 27, 2014, 04:03:06 PM
Hi,

I'm having trouble calibrating my Rev A unit.  When trying to set the Q bias, the maximum output I get with the output knob maxed is .237 volts, far away from the 2.18v needed.  Also, I can clearly hear my test tone coming out of the unit.  I'm thinking this is not normal.

At the Q bias settings specified (noon on input/output, max attack release and 20:1, etc.) I have a .073v reading, where my Q bias adjustment stops increasing.  This seems low. 

I've confirmed my 1k sine test tone going in is at the specified .775v.  Any suggestions?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 28, 2014, 06:30:00 PM
Hi,

I'm having trouble calibrating my Rev A unit.  When trying to set the Q bias, the maximum output I get with the output knob maxed is .237 volts, far away from the 2.18v needed.  Also, I can clearly hear my test tone coming out of the unit.  I'm thinking this is not normal.

At the Q bias settings specified (noon on input/output, max attack release and 20:1, etc.) I have a .073v reading, where my Q bias adjustment stops increasing.  This seems low. 

I've confirmed my 1k sine test tone going in is at the specified .775v.  Any suggestions?

Audible test tones happen, especially if the input is hot.

IF you font have a 500 series extension or jig it's hard to signal trace in the box.  I'd start by checking every single component.  Check that it's value is correct, it's oriented correctly, and all the leads are soldered.  Report back.  This process should take an hour or so.  Since the build has no wiring, it has to be a misplaced component.  Also make sure your meter board is in place, you need it for the unit to calibrate/work.

Most of the issues we had in prototyping involved neglecting to solder a lead.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: rockprocess on October 29, 2014, 07:56:54 AM
Hi,

I'm having trouble calibrating my Rev A unit.  When trying to set the Q bias, the maximum output I get with the output knob maxed is .237 volts, far away from the 2.18v needed.  Also, I can clearly hear my test tone coming out of the unit.  I'm thinking this is not normal.

At the Q bias settings specified (noon on input/output, max attack release and 20:1, etc.) I have a .073v reading, where my Q bias adjustment stops increasing.  This seems low. 

I've confirmed my 1k sine test tone going in is at the specified .775v.  Any suggestions?

Audible test tones happen, especially if the input is hot.

IF you font have a 500 series extension or jig it's hard to signal trace in the box.  I'd start by checking every single component.  Check that it's value is correct, it's oriented correctly, and all the leads are soldered.  Report back.  This process should take an hour or so.  Since the build has no wiring, it has to be a misplaced component.  Also make sure your meter board is in place, you need it for the unit to calibrate/work.

Most of the issues we had in prototyping involved neglecting to solder a lead.

Mike

Thanks Mike.  I went back and double checked each component and reflowed each solder joint.  When trying it fully patched in and out in my DAW, I noticed that the levels were fine, easy capable of more than unity gain.
This made me question my meter reading.  Turns out, I had carelessly used a female XLR to get my pin out, not thinking through that the male XLR that I'll be measuring has the 1 and 3rd terminals flipped.

Sure enough, attaching my meter leads to the correct pin 2 and 3 showed the correct voltage and I was able to calibrate without any issues.  What a great sounding unit!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Lavalier on October 31, 2014, 03:54:45 PM
I've built a stereo pair of these and they really sound great,
however, whenever the attack or release knobs are lightly touched there seems to be some intermittent static coming through the audio path. It's not an issue if you set it and let go. But if you're trying to adjust on the fly while tracking it's pretty unusable.

I've experienced this with both dynamic and condenser. Standard API lunchbox into a 192.
Lifting the ground doesn't make any difference either...

Anyone else had a similar issue?

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on October 31, 2014, 06:20:44 PM
Check continuity between the potentiometer bushings and the metal bracket. You may need to fit the lock washers behind the bracket to allow the bushings to make contact. Please post the result.

I've built a stereo pair of these and they really sound great,
however, whenever the attack or release knobs are lightly touched there seems to be some intermittent static coming through the audio path. It's not an issue if you set it and let go. But if you're trying to adjust on the fly while tracking it's pretty unusable.

I've experienced this with both dynamic and condenser. Standard API lunchbox into a 192.
Lifting the ground doesn't make any difference either...

Anyone else had a similar issue?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: solitud on November 01, 2014, 06:47:38 PM
Hey,
I am building the FET/500 D.
I have a API Lunchbox with  DB25 connectors so the manual suggests that I have to cut a trace on the PCB to prevent default link mode.
But I only have ONE FET/500.
Is it still necessary to cut this trace?

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 01, 2014, 07:32:09 PM
Hey,
I am building the FET/500 D.
I have a API Lunchbox with  DB25 connectors so the manual suggests that I have to cut a trace on the PCB to prevent default link mode.
But I only have ONE FET/500.
Is it still necessary to cut this trace?

No shouldn't be.  Only if another module in the rack uses stereo linking.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: solitud on November 02, 2014, 08:34:16 AM
No shouldn't be.  Only if another module in the rack uses stereo linking.
Thanks for the quick reply! I am very new to 500 series so forgive me if this is a dumb question:
I have a SSL G Comp in the API Lunchbox. This is a stereo module occupying two slots.
Is this considered to be a module that "uses stereo linking" or is it still save to not cut the trace on the FET/500 with the G Comp in the same rack?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 02, 2014, 12:30:44 PM
I would cut it to be safe.  It's simple and then you don't need to worry about it.

The trace is not needed.  It's a redundant trace.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: solitud on November 02, 2014, 02:15:35 PM
O.k., thanks, will do.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: solitud on November 03, 2014, 01:15:38 PM
Another question regarding DOT and BAR modes.  :)
It's stated in the build docs that the FET/500 draws 150mA in DOT mode.
But I couldn't find the specs for BAR mode.
The API lunchbox supplies 215mA per slot.
Will this be sufficient?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: solitud on November 04, 2014, 10:03:53 AM
For knowing not better I sticked to the default DOT mode.
I have finished the build, went through the calibration and everything works like a charm, yeah!
Thanks for this great kit. Packaging was outstanding stylish and the image-map based online build doc was perfect, especially for a noobish builder like me.

I am perfectly happy but found some small things to improve:

Thanks again, all the best,
Knut
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 04, 2014, 11:31:17 AM
For knowing not better I sticked to the default DOT mode.
I have finished the build, went through the calibration and everything works like a charm, yeah!
Thanks for this great kit. Packaging was outstanding stylish and the image-map based online build doc was perfect, especially for a noobish builder like me.

I am perfectly happy but found some small things to improve:
  • My package contained two LM317LZ transistors for the meter board but the BOM just mentioned the one for IC203. I have put the other one in IC205. It seems to belong there.
  • The image map has a small issue there, too. If I hover about IC205, capacitor C205 also lights up.
  • The silkprinting of the trimmers VR1,VR2 does not match the parts orientation-wise.

Thanks again, all the best,
Knut

Ah yes there is an error with IC205/C205 on the build map.  Will fix.  VR1/VR2 should be oriented correctly but may still work backwards.

Not sure of the current draw in BAR mode but you can always try it.  It also depends on the other units in the rack as the all share the same power supply.  So if you have a bunch of units drawing 50mA, that leaves considerably more current for the other modules.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Lavalier on November 06, 2014, 01:42:59 PM
Check continuity between the potentiometer bushings and the metal bracket. You may need to fit the lock washers behind the bracket to allow the bushings to make contact. Please post the result.
Thanks mnats I'll give that a try when I get a chance.

On another note regarding the dot/bar mode. I wanted the option to do either, so I installed switches.
You can actually get them at Radioshack. Model: 275-007  Catalog #: 2750007
http://www.radioshack.com/6vdc-0-3a-dpdt-slide-switch/2750007.html#q=slide%2Bswitch&start=3
You have to clip off the three leads on one side, and then they fit perfectly...
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: rockprocess on November 07, 2014, 10:09:11 PM
I've noticed that the Attack control on my RevA Fet/500 is extremely subtle.  Is this normal?  I'm pretty familiar with 1176's in general and I don't ever recall the attack control being that subtle.

I've already gone back through mine to ensure the pot, cap and resistor in the attack section of the circuit are all correct values, functioning and soldered in fine.  Any thoughts?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 07, 2014, 10:27:29 PM
I've noticed that the Attack control on my RevA Fet/500 is extremely subtle.  Is this normal?  I'm pretty familiar with 1176's in general and I don't ever recall the attack control being that subtle.

I've already gone back through mine to ensure the pot, cap and resistor in the attack section of the circuit are all correct values, functioning and soldered in fine.  Any thoughts?

Pretty much yes.  The attack  is 20 microseconds to 800 microseconds.  That's micro not milliseconds. 

Older units had a pretty unique pot curves which *might* account for a bit of that.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: rockprocess on November 08, 2014, 08:20:41 AM
Would switching the cap, resistor, etc. in the attack circuit to the values of later versions give me longer attack times on the longer end of the range?  I'm looking to keep the fast attack on the short end of the range but be able to dial in longer attack times too. 
I can't tell if doing that would affect the function of other aspects of the circuit or if the attack section of the circuit operates independently. 

Thanks!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Winetree on November 09, 2014, 03:58:02 PM
Version "D"
I can't read the BOM for the meter board because of print overs and parts seem to be different.
Where do they go?

IC 200  ?    Parts in Kit
IC 201  ?    2 - TL 072P
IC 300  ?    1 - CPA 426

IC 203 ?     Parts in Kit
IC 201 ?     2- LM 317
Q 200 ?      1 - 5088

Also E-Mailed
Thanks
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 09, 2014, 11:13:57 PM
Version "D"
I can't read the BOM for the meter board because of print overs and parts seem to be different.
Where do they go?

IC 200  ?    Parts in Kit
IC 201  ?    2 - TL 072P
IC 300  ?    1 - CPA 426

IC 203 ?     Parts in Kit
IC 201 ?     2- LM 317
Q 200 ?      1 - 5088

Also E-Mailed
Thanks

Hmmm must be a browser resolution thing.

You can always see PDF BOMs on the MNATs site.

http://mnats.net/fet500.html
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 09, 2014, 11:15:02 PM
Would switching the cap, resistor, etc. in the attack circuit to the values of later versions give me longer attack times on the longer end of the range?  I'm looking to keep the fast attack on the short end of the range but be able to dial in longer attack times too. 
I can't tell if doing that would affect the function of other aspects of the circuit or if the attack section of the circuit operates independently. 

Thanks!

Either the timing cap or the pot I imagine.

It's on my list of things to do (sorting out attack mods).
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Winetree on November 10, 2014, 12:08:42 AM
Thanks,
Mnats BOM is a lot easier to read in a list form Instead of the Squares.
Mnats color LED layout is different also. I'll use yours as pictured.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: wnlively on November 25, 2014, 05:14:27 PM
Hi
I was wondering if it is possible to purchase the  LED s and meter board for the  FET 500

Thanks
Neal
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: barbaroja on December 02, 2014, 02:43:59 AM
Would be nice to see how it stacks up do don's classics U76A. I am a happy owner. Just a little bit noisy when output is pushed but thats its nature. BTW, dons classics uses all carbon resistors for the signal path so those would add to the noise. I saw metal film resistors for the FET 500 but not sure if all of them are MF. I propose we use some vocal and drum clips and give a run to these pretty things, cant have enough of listening tests!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on December 02, 2014, 02:49:56 AM
Would be nice to see how it stacks up do don's classics U76A. I am a happy owner. Just a little bit noisy when output is pushed but thats its nature. BTW, dons classics uses all carbon resistors for the signal path so those would add to the noise. I saw metal film resistors for the FET 500 but not sure if all of them are MF. I propose we use some vocal and drum clips and give a run to these pretty things, cant have enough of listening tests!

Just a guess but I would assume it's the DC/DC converter that accounts for the noise in the U76A .  I believe that's part of the reason MNATs decided against using  a DC/DC converter in the signal chain and opted for the neg rail audio ground.   Much quieter.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: barbaroja on December 02, 2014, 02:55:47 AM
Is the FET 500 rev A quiet?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on December 02, 2014, 02:58:56 AM
Is the FET 500 rev A quiet?

It tested within the original spec for noise.  It's as quiet as the rack version which is quiet.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: barbaroja on December 02, 2014, 03:00:17 AM
Is the FET 500 rev A quiet?

It tested within the original spec for noise.  It's as quiet as the rack version which is quiet.

A lot of difference with rev D?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on December 02, 2014, 03:06:09 AM
Is the FET 500 rev A quiet?

They are all the same.  I think the A being noiser is a myth.  I've never found it to be noiser.  It has more THD which is different than pure noise (hiss).

It tested within the original spec for noise.  It's as quiet as the rack version which is quiet.

A lot of difference with rev D?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: barbaroja on December 02, 2014, 03:38:50 AM
Thanks for the answers. Do they have any kind of eq or filter in the detector circuit, in a preset way? Such as the screw in the LA2A or the API 2500 thing. I feel the A responded different to peaks than D, (talking about the racked clones). The D being a little more present, or mid forward. Maybe just is a perception or maybe at this late I should be sleeping now...  :P Anyway, it's kind of nitpicking.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: wnlively on December 08, 2014, 05:54:56 PM
I purchased a matched pair of the FET 500 REV D some time , built the first one .
Off during the holidays I started the second build and I have found that for the ceramic capacitor C11 in the second kit I have a 47uf  instead of the  10pf that was in the first kit.  After looking at the BOM on each REV I see thar the 47uf is used on the REV F.

 Can I use the 47uf in the place of the 10pf on the REV D ?

Thanks
Wnlively
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: barbaroja on December 26, 2014, 02:30:55 AM
I have Led 211 half lit all the time. Flux cleaned, connections checked. Any ideas?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on December 26, 2014, 02:37:42 PM
I have Led 211 half lit all the time. Flux cleaned, connections checked. Any ideas?

This is addressed in the LED section of my FET/500 page linked from the first post of this thread.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: barbaroja on December 26, 2014, 02:44:29 PM
I have Led 211 half lit all the time. Flux cleaned, connections checked. Any ideas?

This is addressed in the LED section of my FET/500 page linked from the first post of this thread.

Great! Thanks.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mixedbymike1 on January 03, 2015, 09:36:30 PM
I just built a stereo pair of FET/500s. I built them at the same time, but one of them has an issue with it's True Bypass.

When I press the bypass switch on one unit, the unit does not bypass, nor does the bypass LED come on. I've made sure the relays are oriented correctly, and the solder joints on the relays and switches are clean of any bridges. Any other suggestions on what to check?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on January 04, 2015, 02:54:12 PM
I just built a stereo pair of FET/500s. I built them at the same time, but one of them has an issue with it's True Bypass.

When I press the bypass switch on one unit, the unit does not bypass, nor does the bypass LED come on. I've made sure the relays are oriented correctly, and the solder joints on the relays and switches are clean of any bridges. Any other suggestions on what to check?

The bypass is a series circuit formed by the two relay coils, the LED, a dropping resistor and the switch. This is done for efficiency - putting a unit in bypass doesn't cause it to draw excessive current. However it means that if any one of these circuit elements has an issue the circuit will not work. Possibilities are covered in the General Troubleshooting page linked from the first post, but in order of probability:

Resistor value is incorrect
LED is reversed
Poor solder joint on one or more component(s)
Faulty switch
Faulty relay coil

If you hadn't mentioned it then the relay orientation would have come early in the list.

Please report back with your findings.

 BTW, please see http://garyes.stormloader.com/its.html (http://garyes.stormloader.com/its.html).
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mixedbymike1 on January 05, 2015, 01:42:48 AM
I found the schematic so I should be all set tracking the problem down now. Thanks for your help!

'It's' was a typo, since I don't proofread everything I type on a message board, but since we're on the subject: http://www.writingclasses.com/Products/PubsDetail_Excerpt.php/ExcerptID/434
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: JoelCoteBergevin on January 10, 2015, 10:16:55 AM
I have a problem with my Rev D. After the calibration, I went to put on the faceplate but it wasnt sitting flush so I had to resolder the bypass and the GR off LEDs. However, when I was resoldering the GR off LED, one of the pad came off the PCB.

What can I do to resolder the LED in place ?

Thanks
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 10, 2015, 10:34:01 AM
I have a problem with my Rev D. After the calibration, I went to put on the faceplate but it wasnt sitting flush so I had to resolder the bypass and the GR off LEDs. However, when I was resoldering the GR off LED, one of the pad came off the PCB.

What can I do to resolder the LED in place ?

Thanks

Yikes.  You may want to turn down your iron a little 650-700 degrees is a good range for lead solder.

Solutions:

1) You'll need to make a little wire jumper.  Solder one piece of wire to the lead with the pad missing then follow the trace to see what the next pad the trace connects to and solder the other end there. 

If you download the MNATS project PDF you can see the LED connections on the schematic.  Pretty simple.

http://mnats.net/fet500.html

2) find the trace that connects to the missing pad and scrape off a little solder mask exposing the trace and solder the lead to the trace.

Mike

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 10, 2015, 10:43:04 AM
From the looks of it, if it's the positive/anode lead, it just connects to the pad right beside it for R510.  The cathode or negative lead has a lot further to go. If you look under C21 there should be a little via there, you could jumper over to that.  I'm looking at the D, not sure which rev you have but they all should be pretty similar for the LED circuit.

There night be some repair guys on here with better fixes, but these are generally easy fixes if you take your time.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: JoelCoteBergevin on January 10, 2015, 12:38:21 PM
It's the pad for the cathode. So just solder one end of a wire to the lead and the other end to the via under C21, that's it ?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 10, 2015, 01:25:54 PM
It's the pad for the cathode. So just solder one end of a wire to the lead and the other end to the via under C21, that's it ?
Should work.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: JoelCoteBergevin on January 10, 2015, 08:18:35 PM
Hi !

I did what you told me and it works ! However, I have a question, is it normal that the PEAK LED (led210) lights up even though the signal is definitively not ''clipping'' ? I used it on different sources (mono room, snare, vocals) and it's working perfectly for room and vocals but with the snare it lights up quickly. But I think it's normal since the peaks of the transients on a snare track are pretty strong...

Yes I did follow the calibration steps by steps.

Can you confirm I'm not going crazy ? haha

Thank you
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 11, 2015, 12:01:57 AM
Ya the peak picks up transients.  You're fine!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Tiotever on January 16, 2015, 02:21:06 PM
Hi, I'm just about to start my first FET/500 Rev A build.  I can't seem to find components sorting sheets anywhere on line.   Has anyone posted some already or do i need to make my own?  Thanks!!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 16, 2015, 02:25:17 PM
Hi, I'm just about to start my first FET/500 Rev A build.  I can't seem to find components sorting sheets anywhere on line.   Has anyone posted some already or do i need to make my own?  Thanks!!

I didn't make any sorry.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on January 16, 2015, 08:32:14 PM
I can't seem to find components sorting sheets anywhere on line.   

Sorting sheets? Do you mean the Bill of Materials (linked from the first post)? Or were you looking for something in spreadsheet form?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Tiotever on January 17, 2015, 02:06:40 AM
Hi thanks for the response.  I Made my own. I would share them for other users but they're  not very well done and might cause problems rather than help avoid them. I was looking for files I could print out that I could literally place the resisistors on after testing to help keep them organized and properly identified before stuffing the PCB. Hairball has done them for the Lola pres I built awhile ago. And another DIYer named chunger has done them for other builds I've done. I'm still a newbie so I need these things. But I'm all good and really excited to build this compressor you've designed. Thanks again!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: t_carvalho on January 19, 2015, 11:44:19 AM
Hi.

Just finished building my stereo pair and i just seem to have a small problem with the grayhill ratio pots. Once i insert the knob, the ratios dont align with the pointer in the knob. I followed the instructions in the build guide (set flat side to 7 o´clock and inserted the pins at 12 and 6). In my case, once the knob is inserted, Slam is at 6 o´clock and 2:1 is at 12 o´clock, instead of Slam 9 o´clock and 2:1 at 4 o´clock. I´m also putting the screw of the knob on the flat side of pot. Am i doing something wrong?

Best regards
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 19, 2015, 12:49:08 PM
Sounds like you just need to flip the knob around.

The switch has 12 positions.  6 are used and the other 6 are just duplicated.  You probably have your switch on the other side of the switch which is no issue except you need to flip the knob.

Not sure if that all makes sense.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: t_carvalho on January 19, 2015, 01:38:15 PM
Sounds like you just need to flip the knob around.

The switch has 12 positions.  6 are used and the other 6 are just duplicated.  You probably have your switch on the other side of the switch which is no issue except you need to flip the knob.

Not sure if that all makes sense.

If i flip the knob, the screw wont be secure on the flat side of the trim pot shaft. Even if i remove the pins and and switch the flat side of the shaft to the other side, the pointer in the knob still wont match with the faceplate.

here are some pics:

https://dl.dropboxusercontent.com/u/109310897/Hairball%20FET%20500/Flat%20side%207_oclock.jpg
https://dl.dropboxusercontent.com/u/109310897/Hairball%20FET%20500/2%20to1%20with%20knob.jpg
https://dl.dropboxusercontent.com/u/109310897/Hairball%20FET%20500/Slam%20with%20knob.jpg

Thanks
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 19, 2015, 01:46:27 PM
Sounds like you just need to flip the knob around.

The switch has 12 positions.  6 are used and the other 6 are just duplicated.  You probably have your switch on the other side of the switch which is no issue except you need to flip the knob.

Not sure if that all makes sense.

If i flip the knob, the screw wont be secure on the flat side of the trim pot shaft. So i need to remove the pins, switch the flat side of the trim shaft to the other side and insert the pins again?

Doesn't really matter where the screw hist the shaft.  I think it's best not on the flat of the switch pot for setting it dead on but that's just my experience.

Flip the reducer to the other screw.  Whatever works.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: JoelCoteBergevin on January 28, 2015, 12:33:19 PM
I have a Rev D pair and when assembling the faceplate of my second unit, the yellow GR led broke in half.. I want to buy a couple through mouser. I was wondering what is the part number for the LED ? I'd like to have the exact same thing. Thank you !
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 29, 2015, 02:25:52 PM
I have a Rev D pair and when assembling the faceplate of my second unit, the yellow GR led broke in half.. I want to buy a couple through mouser. I was wondering what is the part number for the LED ? I'd like to have the exact same thing. Thank you !

WP710A10YD
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Tiotever on January 29, 2015, 03:43:47 PM
A few probably stupid questions regarding a REV A build;
1) While populating the meter pcb i encountered some extra resistors and one missing resistor from the set.    So I began triple checking values of resistors already soldered into the pcb.  Several of them were reading 5-20k ohms less than their value prior to being stuffed.   Is this normal or indication that I have stuffed an incorrect resistor along the way?  In particular R206 reads 82k outside of the pcb and it reads 64k when its stuffed.   Also note this is midway through populating the board.  Many holes are still empty. 

2) R222 is 1.2k ohms resistor.   My set came missing this value.  Can I get a Mouser Parts number so I can order the exact intended resistor for R222?

3) Where can I buy extra Grayhill Graphite Stops?  I can't seem to find them sold separately on mouser.  Perhaps you have a Mouser parts number for them or have any suggestions for where I might find them in Los Angeles.    Thanks in advance for the help!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 29, 2015, 04:53:51 PM
A few probably stupid questions regarding a REV A build;
1) While populating the meter pcb i encountered some extra resistors and one missing resistor from the set.    So I began triple checking values of resistors already soldered into the pcb.  Several of them were reading 5-20k ohms less than their value prior to being stuffed.   Is this normal or indication that I have stuffed an incorrect resistor along the way?  In particular R206 reads 82k outside of the pcb and it reads 64k when its stuffed.   Also note this is midway through populating the board.  Many holes are still empty. 

Parallel resistances.  You can't measure resistors in circuit without doing the math of what is in parallel with it.  So it's normal.  To measure something in circuit you either need to a) desolder on leg or b) look at the schematic and calculate the resistors in parallel with it.  For the same reason meters are inaccurate at reading high R resistors.  Especially meters with low input impedance (1M).

Sometimes we mess up the kits and include extra resistors or miss some.  Email us if you're missing some.


2) R222 is 1.2k ohms resistor.   My set came missing this value.  Can I get a Mouser Parts number so I can order the exact intended resistor for R222?

Send us an email.


3) Where can I buy extra Grayhill Graphite Stops?  I can't seem to find them sold separately on mouser.  Perhaps you have a Mouser parts number for them or have any suggestions for where I might find them in Los Angeles.    Thanks in advance for the help!

Send us an email.  We'll get you squared away.

Thanks!

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: pearl on May 07, 2015, 05:20:58 PM
I have a problem with Calibration step 3(Gain Reduction Tracking) on my rev a. The first 2 steps(Qbias Adjustment and VU Meter Calibration) works fine but when im trying to adjust the “Tracking Adj” to led -9 it doesnt work it, stops on led -5.  I have built 2 units and its the same problem with both. any ideas?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 07, 2015, 06:51:15 PM
I have a problem with Calibration step 3(Gain Reduction Tracking) on my rev a. The first 2 steps(Qbias Adjustment and VU Meter Calibration) works fine but when im trying to adjust the “Tracking Adj” to led -9 it doesnt work it, stops on led -5.  I have built 2 units and its the same problem with both. any ideas?

The two trimmers (0 adj and tracking adj) can be finicky.  Start by getting them both in the middle.  Turn until your hear a little "click" which is the end, then rotate the other way 10 times.  Do that to both to center them. 

They kind of interplay with one another, the zero moves quick and the tracking slow so if you get the tracking over rotated, you'll never get it right.  Try again going back and forth in small rotations.

See if that helps.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 20, 2015, 07:34:59 PM
Email Question:
Quote
Hi,
I finally plugged in my two fet/500's rev D
One is working very well except for the metering. I can't seem to calibrate the VU or the peak.
The peak and vu are way to high when set to the output level specified.
The GR seems about right. It sounds great. Should the slam led turn on in slam mode? It doesn't at the moment
My other unit passes audio but doesn't compress at all, the is no difference with GR on or off even with the input cranked.

Slam works like the original.  The unit will peg hard right so the top red button will light and the meter will show GR erratically just like the original.

Often the trimmers can be set way off.  Turn the 0 adjust and GR trimmer till you hear a slight "click" that is the end of the trimmer.  They are 20 turn trimmers so rotate them each back the other way 10 turns and they will be centered.  Now try to calibrate starting with zero adjust.  As you make the adjustment go back and forth make small adjustments.  If that doesn't work, you need to check the metering sections for errors.

For the non compressing one, did the qbias adjustment go well?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mysticmerlin on May 21, 2015, 03:03:39 PM
Email Question:
Quote
Hi,
I finally plugged in my two fet/500's rev D
One is working very well except for the metering. I can't seem to calibrate the VU or the peak.
The peak and vu are way to high when set to the output level specified.
The GR seems about right. It sounds great. Should the slam led turn on in slam mode? It doesn't at the moment
My other unit passes audio but doesn't compress at all, the is no difference with GR on or off even with the input cranked.

Slam works like the original.  The unit will peg hard right so the top red button will light and the meter will show GR erratically just like the original.

Often the trimmers can be set way off.  Turn the 0 adjust and GR trimmer till you hear a slight "click" that is the end of the trimmer.  They are 20 turn trimmers so rotate them each back the other way 10 turns and they will be centered.  Now try to calibrate starting with zero adjust.  As you make the adjustment go back and forth make small adjustments.  If that doesn't work, you need to check the metering sections for errors.

For the non compressing one, did the qbias adjustment go well?

Mike

Thanks for that, On my first unit the lowest I can go to get the peak to turn off is 1.2V , at 4.88v (16dbu) it never goes off
Likewise when I set the output at 0.388v I can only adjust between the 2dn and 3rd yellow led
I set the 20turn trimmers to halfway. The sound is good but the metering is way off

On the other Unit I get compression only with the 20:1 ratio and the GR OFF switch doesn't do anything. I am able to the Qbias and 0.388v output the first green led lights up but I can't adjust to the 2nd. The sound is quickly distorted when I turn up the input. Also the GR leds stay on in bypass/ GRoff .
Any ideas welcome

 
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 22, 2015, 11:54:57 AM
Email Question:
Quote
Hi,
I finally plugged in my two fet/500's rev D
One is working very well except for the metering. I can't seem to calibrate the VU or the peak.
The peak and vu are way to high when set to the output level specified.
The GR seems about right. It sounds great. Should the slam led turn on in slam mode? It doesn't at the moment
My other unit passes audio but doesn't compress at all, the is no difference with GR on or off even with the input cranked.

Slam works like the original.  The unit will peg hard right so the top red button will light and the meter will show GR erratically just like the original.

Often the trimmers can be set way off.  Turn the 0 adjust and GR trimmer till you hear a slight "click" that is the end of the trimmer.  They are 20 turn trimmers so rotate them each back the other way 10 turns and they will be centered.  Now try to calibrate starting with zero adjust.  As you make the adjustment go back and forth make small adjustments.  If that doesn't work, you need to check the metering sections for errors.

For the non compressing one, did the qbias adjustment go well?

Mike

Thanks for that, On my first unit the lowest I can go to get the peak to turn off is 1.2V , at 4.88v (16dbu) it never goes off
Likewise when I set the output at 0.388v I can only adjust between the 2dn and 3rd yellow led
I set the 20turn trimmers to halfway. The sound is good but the metering is way off

On the other Unit I get compression only with the 20:1 ratio and the GR OFF switch doesn't do anything. I am able to the Qbias and 0.388v output the first green led lights up but I can't adjust to the 2nd. The sound is quickly distorted when I turn up the input. Also the GR leds stay on in bypass/ GRoff .
Any ideas welcome

Have you tried swapping meter boards?  Did that fix the one that just has the metering issue?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: spaceboss on June 01, 2015, 06:44:21 PM
So,  question:

Is the red led (which indicates gain reduction in/out necessary?

I literally had a cat jump up on my bench. In knocking the bugger off so that he wouldn't experience the warmth of my Hako iron, I pushed the circuit board away. There was no collateral damage except the red led snapped off and took the surface mount pads with it.  :o

I can live without a gain reduction LED, but if it is needed to complete a circuit, I'd wire one up to board at the proper connection points.

The good news is, if this is the one small issue I have per project, I've already got it out of the way.

Thanks!

 
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on June 01, 2015, 06:57:23 PM
So,  question:

Is the red led (which indicates gain reduction in/out necessary?

I literally had a cat jump up on my bench. In knocking the bugger off so that he wouldn't experience the warmth of my Hako iron, I pushed the circuit board away. There was no collateral damage except the red led snapped off and took the surface mount pads with it.  :o

I can live without a gain reduction LED, but if it is needed to complete a circuit, I'd wire one up to board at the proper connection points.

The good news is, if this is the one small issue I have per project, I've already got it out of the way.

Thanks!

No not necessary.  You could hot wire one on by following the trace to the next connectable point.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: LHS on July 15, 2015, 06:43:38 PM
accidentally posted this in the regular 1176 thread-

I accidentally switched the 100pf nichicon caps with the united chemi con caps on C2500 and C2600 (rev a 500 kit).

I don't have a desoldering gun and my experiences have not been great with removing previously soldered components. How critical is
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on July 15, 2015, 09:41:47 PM
accidentally posted this in the regular 1176 thread-

I accidentally switched the 100pf nichicon caps with the united chemi con caps on C2500 and C2600 (rev a 500 kit).

I don't have a desoldering gun and my experiences have not been great with removing previously soldered components. How critical is

I think you mean 100uF.  The Chemi-Cons are fine if you have the polarity right but I would switch them.  We can send new ones if needed.
Title: Rev D just Quit
Post by: gunner666 on July 18, 2015, 01:35:19 PM
Hi everyone,

  Thanks in advance for the help.  My Rev D was working great for a few months.  Today when I went to use it I had an issue.  Bypassed it's fine.  When it's not bypassed there is only a very faint signal at the output, mostly high end.  The gain reduction meter never moves regardless of input level or ratio.  The output meter gets as high as -10 with everything cranked but oddly enough the peak LED comes on.

  Here's where I am in troubleshooting.  I assume because audio comes through when it's bypassed I can rule out any external cable, rack, patch bay issues.  Because the problem remains when the GR off LED is on I assume the problem must be outside of the gain reduction circuit.  I've looked at the schematic but it's not as simple as my VP26's. 

   If anyone has any advice on where to start I'd greatly appreciate it! I have a scope, tone generator and a 500 extension cable.

Thanks!

-mike
Title: Re: Rev D just Quit
Post by: mnats on July 18, 2015, 04:27:42 PM
As suggested in the Troubleshooting FAQ linked from the first post this is a good place to use a signal tracer. It's worth building a 500 jig if you don't have one already so the module is easily accessible from all sides (you'll mostly want the 'bottom' of the main PCB).

Work in blocks by feeding it a known signal, see if it gets through the input attenuator and transformer, then to the output pot, then through the line amp. Given that it was working and now isn't you may be chasing poor solder joints but keep your mind open and figure out where the signal gets messed up. Your problem will be before that point.

Hi everyone,

  Thanks in advance for the help.  My Rev D was working great for a few months.  Today when I went to use it I had an issue.  Bypassed it's fine.  When it's not bypassed there is only a very faint signal at the output, mostly high end.  The gain reduction meter never moves regardless of input level or ratio.  The output meter gets as high as -10 with everything cranked but oddly enough the peak LED comes on.

  Here's where I am in troubleshooting.  I assume because audio comes through when it's bypassed I can rule out any external cable, rack, patch bay issues.  Because the problem remains when the GR off LED is on I assume the problem must be outside of the gain reduction circuit.  I've looked at the schematic but it's not as simple as my VP26's. 

   If anyone has any advice on where to start I'd greatly appreciate it! I have a scope, tone generator and a 500 extension cable.

Thanks!

-mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: LHS on July 21, 2015, 02:21:50 PM
I was re-soldering the red bypass led and inadvertently lifted the solder pad. I can live with the light not working but will this affect the functionality of unit? Any suggestions for a fix?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on July 21, 2015, 02:40:22 PM
I was re-soldering the red bypass led and inadvertently lifted the solder pad. I can live with the light not working but will this affect the functionality of unit? Any suggestions for a fix?

No it's fine.

You can trace the lifted pad to the next solder pad and connect the LED there or try and scrape away some solder mask on the pad trace and solder there.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 02, 2015, 01:49:25 PM
Moving an e-mail discussion to the support thread.

Basic issue: QBias sets but user can't pass the GR meter calibration. Unit is not compressing.

Instructions to user: If you have little mini grabber leads you can attach them, insert the module and test. The black/common lead always is attached to ground.  You can get ground at D4 on the lead without the line. Check pad 21 voltages. To do that connect the red lead to the point where R52 and R53 connect. So you can clip your lead to one of those resistor leads on the side where they are connected. Check the traces to confirm or use your DMM in Ω.  Now plug it in and power up and test your DC V at that point at 4:1 and 20:1. Should be a negative DC voltage with 4 being small and 20 being big. Now check your AC V where R49 connects to the + side of C19..  Same thing 4 and 20. same thing 4 should be less than 20.

User report:

Pad 21 - R52/R53
20:1 -5.496 DC V
4:1 -1.669 DC

R49/C19
20:1 -  0.274 AC V
4:1 - 0.274 AC V

Pad 21 voltages look ok.  The second AC readings do not. 4:1 should be double that and 20:1 should be 3V AC ish. But I may have had the setting wrong....

--------------------------------------

No try this.  Set your input/output mid way, GR ON (fully CW) and release fully CW.  Connect your probe at pad 22. Best way to get this would be at a leg of R36 and R37 where they connect to each other. Measure your AC V at 20:1 and 4:1.

Under the same conditions, measure your AC V at R49/C19 at 20:1 and 4:1 again.

Mike



Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Santos76 on September 23, 2015, 09:59:28 PM
I just completed my FET 500 REV A and without any input, the unit is outputing a staccato noise. Sort of like choppy white noise. Rhythmic though...it is in perfect time with itself.

When i sweep the attack knob it acts almost like a filter getting to its brightest when it's wide open. The upper portion of LED's continually light up from bottom to top in time with the noise.

Any idea as to where I could have gone wrong? I am overwhelmed as to where I should start the troubleshooting process.

FET/500 page, linked searchable documentation  (http://mnats.net/fet500.html)
Calibration video added! (http://mnats.net/fet500.html#calibration)
General troubleshooting page (http://mnats.net/1176_FAQ.html)
Sub-site for boards and kits (http://www.hairballaudio.com/FET500/)

Please post support questions not covered in the documentation linked above to this thread.

As data is collected I will either update the page(s) linked above or link to the forum posts that cover common build issues or questions from the first or second posts of this thread.

Please keep any commercial discussion or general comments in the White Market thread (http://groupdiy.com/index.php?topic=28923.0). Thank you.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 23, 2015, 10:11:24 PM
I just completed my FET 500 REV A and without any input, the unit is outputing a staccato noise. Sort of like choppy white noise. Rhythmic though...it is in perfect time with itself.

When i sweep the attack knob it acts almost like a filter getting to its brightest when it's wide open. The upper portion of LED's continually light up from bottom to top in time with the noise.

Any idea as to where I could have gone wrong? I am overwhelmed as to where I should start the troubleshooting process.

FET/500 page, linked searchable documentation  (http://mnats.net/fet500.html)
Calibration video added! (http://mnats.net/fet500.html#calibration)
General troubleshooting page (http://mnats.net/1176_FAQ.html)
Sub-site for boards and kits (http://www.hairballaudio.com/FET500/)

Please post support questions not covered in the documentation linked above to this thread.

As data is collected I will either update the page(s) linked above or link to the forum posts that cover common build issues or questions from the first or second posts of this thread.

Please keep any commercial discussion or general comments in the White Market thread (http://groupdiy.com/index.php?topic=28923.0). Thank you.

Unfortunately that could be anything. I'm really stuck as to even suggest where to start. Never heard of that issue and that is VERY general.

If I had to suggest something I'd suggest this in order:

1. Consider just paying the $100 and having us repair it if you're that overwhelmed and not sure where to start.
2. If you're looking for issues...does it work in bypass mode?
3. Keep it in GR OFF mode and look at the top half the schematic. Check all of the components on your PCB and make sure they are the correct value and soldered well.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Santos76 on September 24, 2015, 08:07:40 AM
Thanks Mike,

I want to stubbornly get to the bottom of it myself esp. since I am in Canada and our dollar is so s**t that the repair would cost much more than it would in the states. In all likelihood it is something to do with an early step. Although I had built some CAPI stuff, the build was much simpler on those so my work really improved on this kit...like the resistors on the main board looked like they were done by someone else by the time I got to the meter board! I will go back to the earl stuff and let you know what I find.

Chris
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 24, 2015, 11:52:36 AM
Thanks Mike,

I want to stubbornly get to the bottom of it myself esp. since I am in Canada and our dollar is so s**t that the repair would cost much more than it would in the states. In all likelihood it is something to do with an early step. Although I had built some CAPI stuff, the build was much simpler on those so my work really improved on this kit...like the resistors on the main board looked like they were done by someone else by the time I got to the meter board! I will go back to the earl stuff and let you know what I find.

Chris

Ya I would go through the whole build carefully. Clean it up and confirm values.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: junomat on October 30, 2015, 11:44:58 AM
Hey!

First off, thanks so much for what you do.

I just finished building the FET/500 Rev D. I did the calibration and everything is sounding great, but I can't seem to get the orange LED to light up... If soldered and re-soldered...

Can an LED be bad? Any suggestions on fixing this??
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 30, 2015, 09:54:39 PM
Hey!

First off, thanks so much for what you do.

I just finished building the FET/500 Rev D. I did the calibration and everything is sounding great, but I can't seem to get the orange LED to light up... If soldered and re-soldered...

Can an LED be bad? Any suggestions on fixing this??

You could test the LED with a DMM (check google for methods), see if it's dead.

LED's (and all semi-conduuctors) are sensitive to static electricity and heat when installing. Also, see if either pad is lifted.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: junkface on November 03, 2015, 01:14:52 PM
hey mike, et al,
 was having a problem with my fet 500 (rev F). built and calibrated it up and it was working fine for the few days I first used it. came back from a trip and now it's not passing signal anymore unless it's in bypass. decided to double check all the soldering and in the process mucked up a solder pad for the input xfo. according to the data sheet though, pin 2 (also 3,7) is not connected, which looks in line with the schematic. am I correct that I can just disreguard pin 2 or do I need to jumper it somewhere?
if that's not the issue then I'm waiting for a 500 jig to arrive so i can start signal tracing...
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 03, 2015, 01:21:10 PM
hey mike, et al,
 was having a problem with my fet 500 (rev F). built and calibrated it up and it was working fine for the few days I first used it. came back from a trip and now it's not passing signal anymore unless it's in bypass. decided to double check all the soldering and in the process mucked up a solder pad for the input xfo. according to the data sheet though, pin 2 (also 3,7) is not connected, which looks in line with the schematic. am I correct that I can just disreguard pin 2 or do I need to jumper it somewhere?
if that's not the issue then I'm waiting for a 500 jig to arrive so i can start signal tracing...

Bummer.

Ya pin 2 is not connected. Let us know what you find in the signal trace.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: junkface on November 03, 2015, 02:09:52 PM
hey mike, et al,
 was having a problem with my fet 500 (rev F). built and calibrated it up and it was working fine for the few days I first used it. came back from a trip and now it's not passing signal anymore unless it's in bypass. decided to double check all the soldering and in the process mucked up a solder pad for the input xfo. according to the data sheet though, pin 2 (also 3,7) is not connected, which looks in line with the schematic. am I correct that I can just disreguard pin 2 or do I need to jumper it somewhere?
if that's not the issue then I'm waiting for a 500 jig to arrive so i can start signal tracing...

Bummer.

Ya pin 2 is not connected. Let us know what you find in the signal trace.

Mike
thx. will do
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: junomat on November 07, 2015, 09:45:39 AM
Hey!

First off, thanks so much for what you do.

I just finished building the FET/500 Rev D. I did the calibration and everything is sounding great, but I can't seem to get the orange LED to light up... If soldered and re-soldered...

Can an LED be bad? Any suggestions on fixing this??

You could test the LED with a DMM (check google for methods), see if it's dead.

LED's (and all semi-conduuctors) are sensitive to static electricity and heat when installing. Also, see if either pad is lifted.

Mike

Thanks for responding. It seems like it is fried. How do I purchase a replacement?

And a follow up question.

The attack and release knobs feel much more lose compared to the other pots... Is there a better way to secure them better?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 08, 2015, 03:17:14 PM
Hey!

First off, thanks so much for what you do.

I just finished building the FET/500 Rev D. I did the calibration and everything is sounding great, but I can't seem to get the orange LED to light up... If soldered and re-soldered...

Can an LED be bad? Any suggestions on fixing this??

You could test the LED with a DMM (check google for methods), see if it's dead.

LED's (and all semi-conduuctors) are sensitive to static electricity and heat when installing. Also, see if either pad is lifted.

Mike

Thanks for responding. It seems like it is fried. How do I purchase a replacement?

And a follow up question.

The attack and release knobs feel much more lose compared to the other pots... Is there a better way to secure them better?

Mouser# WP132XND

Loose like rotational?  Part of issue with that circuit having 4 different pots, and no manufacture that makes all 4 values well for a decent cost.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: junomat on November 23, 2015, 01:55:52 PM
Hey!

I am looking at switching out the knobs for the FET500 to look more like the original 1176 knobs....

Can I use the knobs here?
http://www.hairballaudio.com/catalog/parts-store/knobs/3a5a-style-small-skirted-knob (for the input/output)
http://www.hairballaudio.com/catalog/parts-store/knobs/fet-small-knob (for attack/release)

Will there be enough room?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 23, 2015, 03:01:11 PM
Hey!

I am looking at switching out the knobs for the FET500 to look more like the original 1176 knobs....

Can I use the knobs here?
http://www.hairballaudio.com/catalog/parts-store/knobs/3a5a-style-small-skirted-knob (for the input/output)
http://www.hairballaudio.com/catalog/parts-store/knobs/fet-small-knob (for attack/release)

Will there be enough room?

Probably not for the bigger one.

I would use these the second link or these:
http://www.hairballaudio.com/catalog/parts-store/knobs/fet-style-miniature-knob-18-shaft

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: junomat on November 23, 2015, 03:02:41 PM
Thanks. So no mini skirted input/output knobs exist?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 23, 2015, 03:04:04 PM
Thanks. So no mini skirted input/output knobs exist?

Not that we sell or that I know of.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: MChammer on December 08, 2015, 04:23:11 PM
I am having problems with my FET/500. Everything works except for the attack. Also my gain reduction slam led at the top of the compressor is lit when it is not in slam mode? Is this problem just a calibration error?

Any help would be appreciated.

-Michael
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on December 08, 2015, 06:50:59 PM
I am having problems with my FET/500. Everything works except for the attack. Also my gain reduction slam led at the top of the compressor is lit when it is not in slam mode? Is this problem just a calibration error?

Any help would be appreciated.

-Michael

The GR meter is like the original in that it will drift a little from supply to supply (Lunchbox) and even with heat. After it's been in the rack and settled in you want to adjust that with the zero adjust on the front panel to get it back to "0".

The 1176 attack is super fast. Real fast. It's 20 MICRO seconds to 800 MICRO seconds. That's 0.00002 to 0.0008 seconds. If you want less attack you may want to consider a larger attack pot.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: junkface on December 18, 2015, 07:59:45 PM
ok, finally got my extension jig together to have a look at my F. I hooked up my .775 vac 1k signal and realized it is actually passing signal, it just seems really low and GR at most settings (or off) doesn't effect it at all. with input and out put at 12 o'clock I'm getting .15 vac at the output. Then I noticed that it seems to function fine when it's in slam mode, whether the GR off button is engaged or not. Doesn't that slam position just send it through R22, R2, and R24-26 as it would for the other ratios? double checking R23...
 
hey mike, et al,
 was having a problem with my fet 500 (rev F). built and calibrated it up and it was working fine for the few days I first used it. came back from a trip and now it's not passing signal anymore unless it's in bypass. decided to double check all the soldering and in the process mucked up a solder pad for the input xfo. according to the data sheet though, pin 2 (also 3,7) is not connected, which looks in line with the schematic. am I correct that I can just disreguard pin 2 or do I need to jumper it somewhere?
if that's not the issue then I'm waiting for a 500 jig to arrive so i can start signal tracing...

Bummer.

Ya pin 2 is not connected. Let us know what you find in the signal trace.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on December 21, 2015, 02:47:58 PM
ok, finally got my extension jig together to have a look at my F. I hooked up my .775 vac 1k signal and realized it is actually passing signal, it just seems really low and GR at most settings (or off) doesn't effect it at all. with input and out put at 12 o'clock I'm getting .15 vac at the output. Then I noticed that it seems to function fine when it's in slam mode, whether the GR off button is engaged or not. Doesn't that slam position just send it through R22, R2, and R24-26 as it would for the other ratios? double checking R23...
 
hey mike, et al,
 was having a problem with my fet 500 (rev F). built and calibrated it up and it was working fine for the few days I first used it. came back from a trip and now it's not passing signal anymore unless it's in bypass. decided to double check all the soldering and in the process mucked up a solder pad for the input xfo. according to the data sheet though, pin 2 (also 3,7) is not connected, which looks in line with the schematic. am I correct that I can just disreguard pin 2 or do I need to jumper it somewhere?
if that's not the issue then I'm waiting for a 500 jig to arrive so i can start signal tracing...

Bummer.

Ya pin 2 is not connected. Let us know what you find in the signal trace.

Mike

Let's measure some stuff.  Start by measuring DC V at the gate of Q1 and see what you can get when you rotate the qbias pot.  Your common/reference will be the anode side (+) of D4.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: junkface on December 21, 2015, 05:42:34 PM
I get -2.6 V DC at ful CCW, trimming up to 0 at full CW
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on December 21, 2015, 05:54:56 PM
I get -2.6 V DC at ful CCW, trimming up to 0 at full CW

That's good.  Keep it at -2.6 for now. That will pinch off the FET. 

No with the FET gate at -2.6 feed a 1k 0dB signal into the unit. GR OFF, 20:1, attack/release full CW, in/out at 12 o'clock. What is your AC voltage at either pad of C9?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: junkface on December 21, 2015, 11:04:16 PM
2.67 VAC
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on December 21, 2015, 11:51:31 PM
2.67 VAC

That's good.

Double check your resistor values and cap values/orientation in the output stage. It's in the upper between the 100K pot and the output transformer.  Double check your resistors in SW2C and SW2D.

http://mnats.net/files/FET-F500.pdf

Mike

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: junkface on December 22, 2015, 02:09:59 AM
man it musta just been a cold joint somewhere  ::) . double checked everything you mentioned, all the values and orientations were correct. pulled a couple leads to double check I wasn't reading  suspect resistor values backwards and reflowed everything that looked even remotely questionable. now it's workin fine! thanks for your help, if nothing else it's given me a much better understanding of this schematic and pcb layout.  you're the best mang!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: martin bluenoise on January 12, 2016, 02:35:29 PM
Hi guys!

I've got and use a rev A for well over a year and I really like it.

I'm having an issue though. The input pot has gotten scratchy. Only as I turn it. Is this a symptom of something gone wrong during the build or is it just dust? If it's dust, how do I clean it? Contact cleaner?

Thanks a million in advance! 
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 13, 2016, 10:42:04 AM
Hi guys!

I've got and use a rev A for well over a year and I really like it.

I'm having an issue though. The input pot has gotten scratchy. Only as I turn it. Is this a symptom of something gone wrong during the build or is it just dust? If it's dust, how do I clean it? Contact cleaner?

Thanks a million in advance!

If those get dirty they get real noisy. Because it's the input pot, any noise is amplified.

We'll send you a new one if you want to replace it.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: MChammer on February 29, 2016, 02:42:59 PM
I already sent a message to the hairball audio site but I wanted to see if anyone had some suggestions on here. I was calibrating the revision d fet 500 today and the GR meter LEDs were not working properly. Multiple LEDs were lit. For example -9, -7, -3, -2, and -1 would be lit. I have it on the default so only the top LED should be lit. The output is correct when changing from GR off to GR on, only the LEDs seem to be wrong. Any help would be appreciated. I have compared this meter board to a previous working version and I can't find my mistake.

-Michael
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on February 29, 2016, 02:49:58 PM
I already sent a message to the hairball audio site but I wanted to see if anyone had some suggestions on here. I was calibrating the revision d fet 500 today and the GR meter LEDs were not working properly. Multiple LEDs were lit. For example -9, -7, -3, -2, and -1 would be lit. I have it on the default so only the top LED should be lit. The output is correct when changing from GR off to GR on, only the LEDs seem to be wrong. Any help would be appreciated. I have compared this meter board to a previous working version and I can't find my mistake.

-Michael

The GR Meter also has some circuitry down on the main PCB. Everything around IC1:
http://mnats.net/files/FET-D500.pdf

Have a look at all of those parts including the trimmer value.

Re-flow joints if all else fails.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: MChammer on February 29, 2016, 05:00:21 PM
So far I have found out that the problem is not the meter board. The meter board works with my Rev. A perfectly. I re-soldiered many of the joint and the problem still occurs
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on February 29, 2016, 06:24:52 PM
So far I have found out that the problem is not the meter board. The meter board works with my Rev. A perfectly. I re-soldiered many of the joint and the problem still occurs

Right, much oh that circuit is on the main PCB around and including IC1.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: MChammer on March 02, 2016, 12:26:11 AM
I looked into that area on the board. I found nothing on closer examination I found that I had switched the .22 uF capacitors with the 220 pF capacitors. I made a careless mistake when moving decimals, I should have wrote it down. I believe this may be causing my issue. I broke one of the 220 pF ceramic capacitors when removing it, so I ordered some more. They should be in on Thursday or Friday. I have my fingers crossed that once I get the capacitors in the correct places that the calibration and LEDs will behave correctly. (Its weird that the voltage outputs are correct while the LEDs are not).  Anyway I'll let you know how things go. I am using  Rev A and D for my final directed project/dissertation for my masters.

-Thanks for all the help so far!  :D
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: cryptokoan on March 10, 2016, 07:02:01 PM
Hey yall,

Just built a stereo pair of the REV A....sounds awesome!!

One thing I was wondering about.. When I run them into a line mixer, I get very faint clicks that correspond to the gain meter led moving, on both compressors.

However when I run them straight into my converters I get no such problem. Is this a problem with my line mixer? Im just wondering why it would seem to correspond with the fet500 gain meter. Grounding issue?

The clicking is ever so faint,  and only happens when the led is moving. If gain remains below -20 there is no clicking. Any ideas?

-eric
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 15, 2016, 12:34:03 PM
Hey yall,

Just built a stereo pair of the REV A....sounds awesome!!

One thing I was wondering about.. When I run them into a line mixer, I get very faint clicks that correspond to the gain meter led moving, on both compressors.

However when I run them straight into my converters I get no such problem. Is this a problem with my line mixer? Im just wondering why it would seem to correspond with the fet500 gain meter. Grounding issue?

The clicking is ever so faint,  and only happens when the led is moving. If gain remains below -20 there is no clicking. Any ideas?

-eric

That's super weird. Sorry I don't have any idea about that one.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: justinheronmusic on March 18, 2016, 03:06:16 PM
 Everything is plugged in and passing signal. But here are a few of my issues.

1) Gain Reduction Meter is always on, and doesn't move regardless of signal being present.
2) Can't seem to calibrate the +16dbu peak LED.

 Other than that I seem to be doing pretty ok. Has anyone else had this issue,  and can you give me guidance as to where to look for errors?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 18, 2016, 03:45:19 PM
Everything is plugged in and passing signal. But here are a few of my issues.

1) Gain Reduction Meter is always on, and doesn't move regardless of signal being present.
2) Can't seem to calibrate the +16dbu peak LED.

 Other than that I seem to be doing pretty ok. Has anyone else had this issue,  and can you give me guidance as to where to look for errors?

1) Even attempting to calibrate it does nothing? Is it in BAR or DOT mode?
2) Can you calibrate the +4/0?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: justinheronmusic on March 18, 2016, 04:03:28 PM
I've got the GR meter in BAR mode. When I touch the stereo link jack with my finger the GR meter LED's turn off. At the moment the only thing I can calibrate is the Q Bias and the VU Trim.

- No matter how far left or right I turn the Gain Trim, the Peak LED doesn't turn off. If I back the output down to 3.88 or so, then the peak LED turns off as if I have the correct signal. I'm running a -11.9 signal from Pro Tools Signal Gen, which gave me 0.775 VAC, out of an Apollo Twin Solo into the Lindell 503 rack, and measuring at pins 2 & 3 of the XLR.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 18, 2016, 08:32:28 PM
I've got the GR meter in BAR mode. When I touch the stereo link jack with my finger the GR meter LED's turn off. At the moment the only thing I can calibrate is the Q Bias and the VU Trim.

- No matter how far left or right I turn the Gain Trim, the Peak LED doesn't turn off. If I back the output down to 3.88 or so, then the peak LED turns off as if I have the correct signal. I'm running a -11.9 signal from Pro Tools Signal Gen, which gave me 0.775 VAC, out of an Apollo Twin Solo into the Lindell 503 rack, and measuring at pins 2 & 3 of the XLR.

It's go over the meter PCB.  Double check all the component values and reflow and suspect joints. 
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 18, 2016, 08:33:30 PM
Also, remember for the GR meter a lot of that circuitry is on the main PCB around that IC.  Have a good look at that, if you're having trouble calibrating.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: justinheronmusic on March 19, 2016, 11:21:01 AM
Also, remember for the GR meter a lot of that circuitry is on the main PCB around that IC.  Have a good look at that, if you're having trouble calibrating.

 Checked all my values around the Main PCB IC, and the Meter Board. Everything seems to be in order.  I reflowed questionable solder joints.

 I took the GR meter out of BAR mode, and the GR meter is no longer constantly illuminated, but the SLAM light is always on regardless of ratio. Also still having issues with the peak indicator LED, at 4.88 it's always illuminated regardless of the trim pot setting. 
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 19, 2016, 12:44:50 PM
Also, remember for the GR meter a lot of that circuitry is on the main PCB around that IC.  Have a good look at that, if you're having trouble calibrating.

 Checked all my values around the Main PCB IC, and the Meter Board. Everything seems to be in order.  I reflowed questionable solder joints.

 I took the GR meter out of BAR mode, and the GR meter is no longer constantly illuminated, but the SLAM light is always on regardless of ratio. Also still having issues with the peak indicator LED, at 4.88 it's always illuminated regardless of the trim pot setting.

You GR meter in BAR should illuminate and then un-illuminate with GR think of it like the classic 1176 meter?  In dot 0 just should be lit. So calibrating it does nothing? The GR meter doesn't change?

Try setting your pots to the center. Turn till they "click" then rotate back the other way 10 turns and try to set that GR meter.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: justinheronmusic on March 19, 2016, 01:54:06 PM
I've got the GR meter in BAR mode. When I touch the stereo link jack with my finger the GR meter LED's turn off. At the moment the only thing I can calibrate is the Q Bias and the VU Trim.

- No matter how far left or right I turn the Gain Trim, the Peak LED doesn't turn off. If I back the output down to 3.88 or so, then the peak LED turns off as if I have the correct signal. I'm running a -11.9 signal from Pro Tools Signal Gen, which gave me 0.775 VAC, out of an Apollo Twin Solo into the Lindell 503 rack, and measuring at pins 2 & 3 of the XLR.

It's go over the meter PCB.  Double check all the component values and reflow and suspect joints.

After setting the zero adjust to the middle position, GR Meter is functioning, I was able to zero adjust properly. Here are my current issues:

-  @4.88 output and peak LED is always on despite the Gain Trim pot.
- Tracking adjust doesn't affect GR meter
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: justinheronmusic on March 19, 2016, 03:57:29 PM
Ok, I successfully calibrated the GR tracking. You were right, it was the position of the trim pots. I reset them all and it did wonders for the calibration process.

 Still lost on the Peak indicator LED though. That's still not working for me.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on March 19, 2016, 10:00:34 PM
Still lost on the Peak indicator LED though. That's still not working for me.

Check all the usual things listed in the General Troubleshooting page linked from the first post of this thread. Report back after you've done so.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Sinkia on March 24, 2016, 12:18:23 PM
Hi Mike

We have order a fet500 revA over here on France ! I'm currently building it.
It appears alle the screws & standoff are missing from the boxes.
Is it an error from yours or de has to buy it separatly? (I gave check on the élément Copper we bought to, thosese screws & standoff are inside)
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 24, 2016, 12:27:55 PM
Hi Mike

We have order a fet500 revA over here on France ! I'm currently building it.
It appears alle the screws & standoff are missing from the boxes.
Is it an error from yours or de has to buy it separatly? (I gave check on the élément Copper we bought to, thosese screws & standoff are inside)

No they should be in there. 

Do a full inventory and send us a list of what you're missing to "info (at) hairballaudio (dot) com".

Thanks!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mhbunch on March 24, 2016, 12:33:47 PM
Hey Mike,

I have a super weird issue. I built a rev A in January and it was working great and sounding KILLER until last week all of a sudden it just stopped working. I turned on my lunchbox and the "slam" light was always lit no matter what position i had the ratio on. When I tried running audio it wasnt compressing. I took it out and checked all solder points thinking it might be a short and touched up a few spots that seemed mayybe questionable but overall its a pretty clean job. Put it back in the lunchbox and now the slam light isnt lit but it still wont compress at all. All other functions work ( input, output, gr off [no saturation tho], bypass).

Any clue what might be going on? Maybe one of my trimmers fried?

thanks!

Mackenzie

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 24, 2016, 01:52:07 PM
Hey Mike,

I have a super weird issue. I built a rev A in January and it was working great and sounding KILLER until last week all of a sudden it just stopped working. I turned on my lunchbox and the "slam" light was always lit no matter what position i had the ratio on. When I tried running audio it wasnt compressing. I took it out and checked all solder points thinking it might be a short and touched up a few spots that seemed mayybe questionable but overall its a pretty clean job. Put it back in the lunchbox and now the slam light isnt lit but it still wont compress at all. All other functions work ( input, output, gr off [no saturation tho], bypass).

Any clue what might be going on? Maybe one of my trimmers fried?

thanks!

Mackenzie

Doubt it's a trimmer. If anything failed, it would be something like a transistor or diode.  Some times it's a bad point or some connection is loose.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mhbunch on March 24, 2016, 08:54:38 PM
Hey Mike,

I have a super weird issue. I built a rev A in January and it was working great and sounding KILLER until last week all of a sudden it just stopped working. I turned on my lunchbox and the "slam" light was always lit no matter what position i had the ratio on. When I tried running audio it wasnt compressing. I took it out and checked all solder points thinking it might be a short and touched up a few spots that seemed mayybe questionable but overall its a pretty clean job. Put it back in the lunchbox and now the slam light isnt lit but it still wont compress at all. All other functions work ( input, output, gr off [no saturation tho], bypass).

Any clue what might be going on? Maybe one of my trimmers fried?

thanks!

Mackenzie

Doubt it's a trimmer. If anything failed, it would be something like a transistor or diode.  Some times it's a bad point or some connection is loose.

Mike

Could you point me in the right direction to start poking around? The unit still passes audio when engaged and the input and output effect the signal level, the output meter works but no leds in the gr meter are lighting
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 24, 2016, 10:17:00 PM
Hey Mike,

I have a super weird issue. I built a rev A in January and it was working great and sounding KILLER until last week all of a sudden it just stopped working. I turned on my lunchbox and the "slam" light was always lit no matter what position i had the ratio on. When I tried running audio it wasnt compressing. I took it out and checked all solder points thinking it might be a short and touched up a few spots that seemed mayybe questionable but overall its a pretty clean job. Put it back in the lunchbox and now the slam light isnt lit but it still wont compress at all. All other functions work ( input, output, gr off [no saturation tho], bypass).

Any clue what might be going on? Maybe one of my trimmers fried?

thanks!

Mackenzie

Doubt it's a trimmer. If anything failed, it would be something like a transistor or diode.  Some times it's a bad point or some connection is loose.

Mike

Could you point me in the right direction to start poking around? The unit still passes audio when engaged and the input and output effect the signal level, the output meter works but no leds in the gr meter are lighting

Do you have two of them? If you do swap the meter PCBs and see if the issue follows the meter PCB.

If you only have one, look at the meter PBC and re-seat it.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: zarndyhoff on March 28, 2016, 03:33:50 AM
Hey Mike (or anyone that can offer advice),

I bought a pair of FET500 rev D kits, first one works great, second one not so well.

I've checked and rechecked the solder points, and I've gone through the BOM and verified that each resistor is correct. I've verified that each polarised cap is facing the right way, and that all diodes are facing the right way.

My problematic 1176 is making 'starved voltage' sounds and requires unreal amounts of input gain to register any signal at the output (there don't seem to be any issues with the input registering signal). However, at the output it's making clipping and farting noises.

Here are two videos I made detailing the symptoms. The first video shows the output gain problems, and the second video shows the noise my unit makes.

Apologies for my New Zealand accent!!

Thanks, Alex Harmer.

https://www.youtube.com/watch?v=o9RC4MRNCqg

https://www.youtube.com/watch?v=DqILqkZGpfQ
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 28, 2016, 01:38:10 PM
Hey Mike (or anyone that can offer advice),

I bought a pair of FET500 rev D kits, first one works great, second one not so well.

I've checked and rechecked the solder points, and I've gone through the BOM and verified that each resistor is correct. I've verified that each polarised cap is facing the right way, and that all diodes are facing the right way.

My problematic 1176 is making 'starved voltage' sounds and requires unreal amounts of input gain to register any signal at the output (there don't seem to be any issues with the input registering signal). However, at the output it's making clipping and farting noises.

Here are two videos I made detailing the symptoms. The first video shows the output gain problems, and the second video shows the noise my unit makes.

Apologies for my New Zealand accent!!

Thanks, Alex Harmer.

https://www.youtube.com/watch?v=o9RC4MRNCqg

https://www.youtube.com/watch?v=DqILqkZGpfQ

If you (carefully) remove the Q1 FET does that give you more gain?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: zarndyhoff on March 29, 2016, 12:43:55 AM

If you (carefully) remove the Q1 FET does that give you more gain?

Mike

Hi Mike,

...no, issue is unchanged. I measured voltage and the values were the same. And it was making the same sounds.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 01, 2016, 02:27:28 PM

If you (carefully) remove the Q1 FET does that give you more gain?

Mike

Hi Mike,

...no, issue is unchanged. I measured voltage and the values were the same. And it was making the same sounds.

You've got something in the gain sections.

http://mnats.net/files/FET-D500.pdf

se the parts in the schematic in the top 1/3. Something up there. Check R values, cap polarity, reflow joints.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Stonecutter67 on April 07, 2016, 10:43:12 PM
Ok, not sure I'm posting in the right place but... I just completed 2 builds of FET 500 Rev D's.( I am not a complete novice. I have built a Lola and 8 other preamps from another company but I'm certainly not an expert.)  I put the first unit in my rack and set up the 0 db(.775v) 1K signal on the input. Measuring the output to begin the calibration process, the maximum reading I can get for the Q bias is 2.64v.  Any advise on where I should start looking for errors in my build?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 11, 2016, 12:26:10 PM
Ok, not sure I'm posting in the right place but... I just completed 2 builds of FET 500 Rev D's.( I am not a complete novice. I have built a Lola and 8 other preamps from another company but I'm certainly not an expert.)  I put the first unit in my rack and set up the 0 db(.775v) 1K signal on the input. Measuring the output to begin the calibration process, the maximum reading I can get for the Q bias is 2.64v.  Any advise on where I should start looking for errors in my build?

Are you sure you have the bias all the way out.  Does rotating the bias change the output level?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Stonecutter67 on April 13, 2016, 09:41:58 AM

No. So I went over both builds to check solder joints. I found a couple un-soldered leads and fixed that. I put both units in the rack (separately), sent the signal and the first one measured around the same 2.5 v and no adjustment made any difference. I walked away for a bit (frustrated) and when I came back it the meeter was displaying around 22 v! Again adjustments made no change. I took that one out and put the other one in and it read around 6.5 v.  Adjustments made tiny changes but never more than 6.7 v.
 I've done something wrong... and apparently twice... (which would make a good blues song) LOL!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 14, 2016, 11:01:16 AM

No. So I went over both builds to check solder joints. I found a couple un-soldered leads and fixed that. I put both units in the rack (separately), sent the signal and the first one measured around the same 2.5 v and no adjustment made any difference. I walked away for a bit (frustrated) and when I came back it the meeter was displaying around 22 v! Again adjustments made no change. I took that one out and put the other one in and it read around 6.5 v.  Adjustments made tiny changes but never more than 6.7 v.
 I've done something wrong... and apparently twice... (which would make a good blues song) LOL!

The 22V thing was probably some oscillation.

Sounds like you have the same stuffing error in both.  You could send 1 in for repair. We'll fix it and tell you what you did wrong and then you could check the other on yourself.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: zarndyhoff on April 17, 2016, 10:45:36 PM
Issue now resolved, thanks Mike.

Resistor was marked as a 1.8 meg, actually measuring 180k, in a spot meant for a 180 ohm.   :o

All sorted now, both calibrated and sounding awesome. Keep an eye out for sound examples - no one else seems to have them so I'm going to make some for the greater good. These things rock!


If you (carefully) remove the Q1 FET does that give you more gain?

Mike

Hi Mike,

...no, issue is unchanged. I measured voltage and the values were the same. And it was making the same sounds.

You've got something in the gain sections.

http://mnats.net/files/FET-D500.pdf

se the parts in the schematic in the top 1/3. Something up there. Check R values, cap polarity, reflow joints.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Stonecutter67 on April 20, 2016, 09:28:57 AM

No. So I went over both builds to check solder joints. I found a couple un-soldered leads and fixed that. I put both units in the rack (separately), sent the signal and the first one measured around the same 2.5 v and no adjustment made any difference. I walked away for a bit (frustrated) and when I came back it the meeter was displaying around 22 v! Again adjustments made no change. I took that one out and put the other one in and it read around 6.5 v.  Adjustments made tiny changes but never more than 6.7 v.
 I've done something wrong... and apparently twice... (which would make a good blues song) LOL!

The 22V thing was probably some oscillation.

Sounds like you have the same stuffing error in both.  You could send 1 in for repair. We'll fix it and tell you what you did wrong and then you could check the other on yourself.

Update:
I went over both builds again, checked every resistor, cap and diode orientation, etc. and didn't find anything out of place. The only thing I hadn't done was center all the trimmers. So I did that and tried again. The first one I was only able to get 5v on the q-bias but I went ahead with the calibration anyway and was successful! Seems to be working great. The second one I'm still having problems with. I put it in and immediately get 22v on q-bias. Adjusting the trimmer makes no change. I'm not opposed to sending it in for repair but it seems like this should be something obvious. Any thoughts?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 20, 2016, 03:28:03 PM
Has to be some kind of oscillation.  Make sure you don't have some mix up like a  470, 47K, 470K resistor swap.

Outside of that, it's hard to say...look for short...re-flow suspect joints.

Mike

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Stonecutter67 on April 24, 2016, 09:47:06 PM
Has to be some kind of oscillation.  Make sure you don't have some mix up like a  470, 47K, 470K resistor swap.

Outside of that, it's hard to say...look for short...re-flow suspect joints.

Mike

Well... I'm gonna have to throw my hands up and surrender.  :D I went through the build again, found nothing wrong, re-flowed the joints, put it back together and when i tried to do the Q-bias I only got 2.5 volts. ( the other one I only got 4.5 volts... but I was able to finish the calibration.) I tried to finish with the 2.5v, but I couldn't get to the next step because I was unable to get 4.88v from the output. I think I'd better "cut my losses" and send it in for repair.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Sinkia on April 25, 2016, 12:25:22 PM
Hey Mike I have finish my rev A from your, this units is awesome !

Thanks for your calibration video ! appears to be way more easier from the mnats version..

Can I ask you why you start with the Qbias, when Mnat's start with meters?

I was having trouble when I started with meters, but then with your video, everything went smooth !

Here, I have a question for you !

I'm about to order an other analog fet/500 rev A to make a couple. do you think you could send me with my new order a stereo matched FETs and a link cable?

Like thant I can change the fet from the first one I bought and have a real "couple"v

Best !
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 25, 2016, 01:55:53 PM
Has to be some kind of oscillation.  Make sure you don't have some mix up like a  470, 47K, 470K resistor swap.

Outside of that, it's hard to say...look for short...re-flow suspect joints.

Mike

Well... I'm gonna have to throw my hands up and surrender.  :D I went through the build again, found nothing wrong, re-flowed the joints, put it back together and when i tried to do the Q-bias I only got 2.5 volts. ( the other one I only got 4.5 volts... but I was able to finish the calibration.) I tried to finish with the 2.5v, but I couldn't get to the next step because I was unable to get 4.88v from the output. I think I'd better "cut my losses" and send it in for repair.

Sorry I don't know what the voltages convert to dbu off the top of my head.  In bypass mode for a 1K 0dbu signal and the in/out centered you should have about 16dbu on the output with the rev D (19dbu with the A).

Looking at the math the 4.5VAC (about 16dBu) one seems to be working fine.

Mike

http://www.sengpielaudio.com/calculator-volt.htm
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 25, 2016, 01:59:43 PM
Can I ask you why you start with the Qbias, when Mnat's start with meters?

I'm about to order an other analog fet/500 rev A to make a couple. do you think you could send me with my new order a stereo matched FETs and a link cable?

Like thant I can change the fet from the first one I bought and have a real "couple"v

Best !

The meter and qbias are separate calibrations so it doesn't mater which you start with as long as you start all calibration with the FET Qbias adjustment set to have the FET out of conduction.  If the qbias has the FET dumping a ton of signal to ground, the meter cal will not go well.

Sure just place an order and email up after, we'll toss in stereo FETs and a link cable.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Sinkia on April 25, 2016, 04:41:53 PM

Sure just place an order and email up after, we'll toss in stereo FETs and a link cable.

Mike

Awesome!

I'll let you know!
Title: Re: [BUILD] FET/500 Official Support Thread - Hot Levels
Post by: nick. on April 30, 2016, 03:18:10 PM
I bought a pre assembled FET 500 Rev A. I had an engineer come to my home studio to help me track some drums and he was saying that the FET 500 input seemed rather hot compared to all the compressors he has used. It does seem a little hot to me as well. My input and output never go past 12 o'clock, something they hang out at 9 o'clock. I'm going into it with a Neve 1073 LB and that pre never peaks into yellow or red territory. I don't have any of the gear MNATS has in the Youtube calibration video. Should I send it to Hairball to be serviced? Any quick ways to check if it is not calibrated correctly?
Title: Re: [BUILD] FET/500 Official Support Thread - Hot Levels
Post by: Hairball Audio on May 02, 2016, 01:58:43 PM
The rev A is hotter than the other revs. 5dB which is almost double the voltage gain.

Also, the UREI pots have a very odd taper.  You just don't see tapers like that anymore.

Mike

I bought a pre assembled FET 500 Rev A. I had an engineer come to my home studio to help me track some drums and he was saying that the FET 500 input seemed rather hot compared to all the compressors he has used. It does seem a little hot to me as well. My input and output never go past 12 o'clock, something they hang out at 9 o'clock. I'm going into it with a Neve 1073 LB and that pre never peaks into yellow or red territory. I don't have any of the gear MNATS has in the Youtube calibration video. Should I send it to Hairball to be serviced? Any quick ways to check if it is not calibrated correctly?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: thp on May 16, 2016, 10:41:16 PM
I am building 2 Rev A's simultaneously.  I am at the blue ceramic cap installation part of the build guide and am having trouble identifying which go where.

One of my kits comes with 2 blue caps that are marked 104 and the other kit comes with 2 that are marked 6R8.
Are these the same? 
The guide says that 104 = 0.1uf but there is only a space for 1 - C160.  Where does the second one go?

Each kit comes with 1 blue cap that says 100.  Where does this go?

Each kit comes with 1 blue cap that says 330.  Does this go C016?

Each kit comes with 1 blue cap that says 102.  Where does this go?


Also, we have 3 cream Kemet caps that are .15uf, yet the build guide says that Rev A only uses 2, C2 and C8.
Is this an error because there is a spot, C1, for a third one as well?


Thanks for the help!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 16, 2016, 10:47:45 PM
I am building 2 Rev A's simultaneously.  I am at the blue ceramic cap installation part of the build guide and am having trouble identifying which go where.

One of my kits comes with 2 blue caps that are marked 104 and the other kit comes with 2 that are marked 6R8.
Are these the same? 

No one is a 0.1uF and one is a 6.8pF

The guide says that 104 = 0.1uf but there is only a space for 1 - C160.  Where does the second one go?

I'm not sure how many there should be and I'm too exhausted to look right now, but are you using the build maps?  Sometimes we mess up though and there are extras or shorts.

Each kit comes with 1 blue cap that says 100.  Where does this go?

Each kit comes with 1 blue cap that says 330.  Does this go C016?

Each kit comes with 1 blue cap that says 102.  Where does this go?

10pF
33pF
.001uF

Check the build map.

Also, we have 3 cream Kemet caps that are .15uf, yet the build guide says that Rev A only uses 2, C2 and C8.
Is this an error because there is a spot, C1, for a third one as well?


Thanks for the help!

Yes should be 3 for those spots.


Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 16, 2016, 10:48:53 PM
REV A Main
http://library.hairballaudio.com/maps/reva500/

Meter
http://library.hairballaudio.com/maps/meter500/

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: thp on June 11, 2016, 01:20:55 PM
I finished building the pair of revision A's
Both sound great but one is a little weird with the meters.

with gain reduction bypassed and all knobs in the middle,
 if I turn release full clockwise, 0 & Slam light up
if I turn release full counter clockwise -1 lights up

if i engage gain reduction, it does one of the above -
turning release full counter clockwise -1 lights up

Is it just a calibration issue, what should I do?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: thp on June 13, 2016, 10:08:10 PM
Any thoughts on what's going on?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on June 20, 2016, 01:21:21 PM
Any thoughts on what's going on?

It's normal for the release to to effect the meter a little.  This is true of the vintage units where under the same conditions you may see a little meter drift.

Are the leads on your output transformer very long? They should be a short s possible.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Ragan on July 01, 2016, 04:30:49 PM
I've just completed a FET 500 Rev A and am trying to get it calibrated correctly. 

Everything is working correctly except one thing. The gain trim (internal) has no effect on the output voltage. So in the step where you adjust that gain trim to calibrate the meter, I can't get anything to happen.

I've been emailing Mike at Hairball (who's been very helpful) but I haven't been able to get it sorted out after trying his suggestions (checking/reflowing any suspect joints on the meter board).

Anyone have any suggestions?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mattjhuber on August 11, 2016, 01:41:49 PM
Hey all!

I have a Rev D.

Audio works fine; I was able to calibrate q bias just fine.

But, when I get to calibrating the meters, it's basically a no-go. I can't get the peak LED calibrated, but at this step:

"Adjust the VR2 "VU Trim" until the -10 LED LED starts to illuminate."

VR2 does nothing to affect the meters. The 0 Adj also does nothing on the subsequent steps.

I have re-flowed all solder points on the meter board, and it appears that all resistors are the correct value.

Any ideas on how to get to the bottom of this?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on August 11, 2016, 01:46:00 PM
Hey all!

I have a Rev D.

Audio works fine; I was able to calibrate q bias just fine.

But, when I get to calibrating the meters, it's basically a no-go. I can't get the peak LED calibrated, but at this step:

"Adjust the VR2 "VU Trim" until the -10 LED LED starts to illuminate."

VR2 does nothing to affect the meters. The 0 Adj also does nothing on the subsequent steps.

I have re-flowed all solder points on the meter board, and it appears that all resistors are the correct value.

Any ideas on how to get to the bottom of this?

Some of that circuit is on the main PCB as well.  Around IC1.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Musepro on October 03, 2016, 11:56:23 PM
Hey gang,

So I am having the most odd problem with my pair of FET/500 RevAs.

Both of them calibrate properly: Q-bias, VU meter with VR2 for -10 and VR1 for Peak, GR meter using 0 adj. for 0 and tracking adj. for -9. All voltages comply with the calibrate guide sending an exact 0.775VAC from my generator. Both units SOUND good.

BUT, here's the problem: both GR meters work IN REVERSE, starting at -22 and moving toward 0 and I can HEAR compression before the meter shows anything.

Obviously, something has gone awry, but I cannot figure it out! I have gone over both PCBs over and over again using both the Hairball BOM and the MNATs BOM, verifying correct placements and polarities. The only thing I see odd is that both IC204s have a different manufacturer number and printing - even though they're the same part number - so that doesn't seem to be the issue. All of the solder joints are clean, shiny and isolated.

Is there something painfully obvious I have missed? Attached are photos of one of the builds. Thanks!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 04, 2016, 12:02:36 AM
Hey gang,

So I am having the most odd problem with my pair of FET/500 RevAs.

Both of them calibrate properly: Q-bias, VU meter with VR2 for -10 and VR1 for Peak, GR meter using 0 adj. for 0 and tracking adj. for -9. All voltages comply with the calibrate guide sending an exact 0.775VAC from my generator. Both units SOUND good.

BUT, here's the problem: both GR meters work IN REVERSE, starting at -22 and moving toward 0 and I can HEAR compression before the meter shows anything.

Obviously, something has gone awry, but I cannot figure it out! I have gone over both PCBs over and over again using both the Hairball BOM and the MNATs BOM, verifying correct placements and polarities. The only thing I see odd is that both IC204s have a different manufacturer number and printing - even though they're the same part number - so that doesn't seem to be the issue. All of the solder joints are clean, shiny and isolated.

Is there something painfully obvious I have missed? Attached are photos of one of the builds. Thanks!

1) Is it in dot or bar mode?
2) Were you able to calibrate the metere for a -9db drop?
3) Does it rest at 0?
4) Sure your not compressing heavy past -22 and just seeing the release coming back to 0? Hard compression will bounce past -22.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Musepro on October 04, 2016, 12:15:30 AM
1) Is it in dot or bar mode?
2) Were you able to calibrate the metere for a -9db drop?
3) Does it rest at 0?
4) Sure your not compressing heavy past -22 and just seeing the release coming back to 0? Hard compression will bounce past -22.

Mike

1) It is in bar mode.
2) Yes, meter calibrated to -9 using tracking adjust - everything went accordingly with the calibrate guide.
3) No, it does not rest at 0 - 0 never lights up at all.
4) Positive I'm not slamming it that hard. I bring input up, start hearing compression, then the GR starts lighting up from -22 going toward 0 as I apply more compression.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 04, 2016, 12:21:23 AM
1) It is in bar mode.
2) Yes, meter calibrated to -9 using tracking adjust - everything went accordingly with the calibrate guide.
3) No, it does not rest at 0 - 0 never lights up at all.
4) Positive I'm not slamming it that hard. I bring input up, start hearing compression, then the GR starts lighting up from -22 going toward 0 as I apply more compression.

I'm confused, it would have to rest at zero to complete that GR meter calibration step. Getting it to rest at 0 is part of that calibration step.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Musepro on October 04, 2016, 12:37:06 AM
I'm confused, it would have to rest at zero to complete that GR meter calibration step. Getting it to rest at 0 is part of that calibration step.

OK - see that's the issue, my GR meter is fully lit up when I adjust for the 0 LED to light. Following the guide and setting the output GR ON and input GR OFF  controls over and over again until both read 0dBu and +9dBu in their respective modes, I adjust the "0 adj" trimmer until 0 lights up - BUT, the entire GR meter is lit up when I do this. I didn't even think about the entire meter being lit up when I did this, I just got the correct voltage readings and turned "0 adj" until 0 lit up!

I've built/calibrated 4 CAPI FC526s that went without a hitch first time around and are happily sitting in my rack with a 0 light lit up. This doesn't answer my question - but I should have noticed the entire GR meter lighted!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 04, 2016, 12:43:57 AM
OK - see that's the issue, my GR meter is fully lit up when I adjust for the 0 LED to light. Following the guide and setting the output GR ON and input GR OFF  controls over and over again until both read 0dBu and +9dBu in their respective modes, I adjust the "0 adj" trimmer until 0 lights up - BUT, the entire GR meter is lit up when I do this. I didn't even think about the entire meter being lit up when I did this, I just got the correct voltage readings and turned "0 adj" until 0 lit up!

I've built/calibrated 4 CAPI FC526s that went without a hitch first time around and are happily sitting in my rack with a 0 light lit up. This doesn't answer my question - but I should have noticed the entire GR meter lighted!

I'm confused. 

So you have it in bar mode. It's like a meter on an 1176 sitting at zero. When operating properly the meter should sit at zero when in GR off or with no signal. If you have it in BAR it'll be all lit up.

Then when you apply compression it the meter lights move down like on the analog 1176 meter.

That's not what your seeing> Or you can't calibrate it?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Musepro on October 04, 2016, 01:00:09 AM
I'm confused. 

So you have it in bar mode. It's like a meter on an 1176 sitting at zero. When operating properly the meter should sit at zero when in GR off or with no signal. If you have it in BAR it'll be all lit up.

Then when you apply compression it the meter lights move down like on the analog 1176 meter.

That's not what your seeing> Or you can't calibrate it?

Mike

Yes, the meter should sit at zero, then dive down when compression starts, just like my FC526s do. My FET/500s show no LEDs lit on the GR meter, you hear compression, then -22 lights up and the meter moves towards 0 the deeper you push into compression - literally backwards - and unlike any real 1176 I have used (or any other compressors for that matter).

As for the calibration, I can follow every step in the guide and get all correct readings/voltages, however, my GR meter is lit fully up when I have it set to calibrate for 0. I just turned the trimmer until 0 lit up and didn't even think about the whole bar being lit.

Maybe my bar mode jumpers are causing some kind of an issue?

UPDATE: I went back and snipped the bar mode jumper on the GR meter. Now when I calibrate, 0 lights up, but as soon as I take it out of SLAM, the 0 LED goes out and the GR meter still moves from -22 toward 0, backwards, when compressing a signal. I can email you a video of this behavior if it helps.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 04, 2016, 01:12:18 AM
Yes, the meter should sit at zero, then dive down when compression starts, just like my FC526s do. My FET/500s show no LEDs lit on the GR meter, you hear compression, then -22 lights up and the meter moves towards 0 the deeper you push into compression - literally backwards - and unlike any real 1176 I have used (or any other compressors for that matter).

As for the calibration, I can follow every step in the guide and get all correct readings/voltages, however, my GR meter is lit fully up when I have it set to calibrate for 0. I just turned the trimmer until 0 lit up and didn't even think about the whole bar being lit.

Maybe my bar mode jumpers are causing some kind of an issue?

No, we have some in bar mode here working well.

What's confusing me (maybe I'm too tired) is in the first part of your statement it seems you say the meter is all unlit...and only lights as you increase the compression and it lights from the bottom up.

But in the second part is seems you're saying you can calibrate it for zero and it's all lit up.

So is it all lit up or off in GR OFF mode.
What happens when you turn GR on with no signal?

Mike

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 04, 2016, 01:14:14 AM
Yes, the meter should sit at zero, then dive down when compression starts, just like my FC526s do. My FET/500s show no LEDs lit on the GR meter, you hear compression, then -22 lights up and the meter moves towards 0 the deeper you push into compression - literally backwards - and unlike any real 1176 I have used (or any other compressors for that matter).

As for the calibration, I can follow every step in the guide and get all correct readings/voltages, however, my GR meter is lit fully up when I have it set to calibrate for 0. I just turned the trimmer until 0 lit up and didn't even think about the whole bar being lit.

Maybe my bar mode jumpers are causing some kind of an issue?

UPDATE: I went back and snipped the bar mode jumper on the GR meter. Now when I calibrate, 0 lights up, but as soon as I take it out of SLAM, the 0 LED goes out and the GR meter still moves from -22 toward 0, backwards, when compressing a signal. I can email you a video of this behavior if it helps.

Are you calibrating in SLAM? You can't so that. You need to calibrate in 20:1.

Calibrating in SLAM will definitely mess up the meter. In SLAM your meter should be pegged in the highest RED LED.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Musepro on October 04, 2016, 12:58:32 PM
Are you calibrating in SLAM? You can't so that. You need to calibrate in 20:1.

Calibrating in SLAM will definitely mess up the meter. In SLAM your meter should be pegged in the highest RED LED.

Mike

Oh good heavens, I was calibrating with all the knobs off and had the ratio switch set to the wrong value! Such a ridiculous oversight on my behalf. Now they are behaving in all respects as I would expect.

So after recalibrating both units from the beginning, this time assured I was in 20:1, both units work perfectly with the GR meter in dot mode. However, when I bridge the pads for bar mode, the entire GR meter lights up, both in GR IN or OUT, and when compressing, GR is shown by LEDs going out from 0 down, not coming on. So my GR bar mode is still acting funny (my VU bar mode had always been fine). I have a video of this behavior if it would help to see.

So sorry I overlooked my ratio settings - I thought I had them in 20:1 the first time around. But I still have odd behavior in bar mode, so hopefully this can be worked out easily. Thank you for your patience and help!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 04, 2016, 01:31:26 PM
Oh good heavens, I was calibrating with all the knobs off and had the ratio switch set to the wrong value! Such a ridiculous oversight on my behalf. Now they are behaving in all respects as I would expect.

So after recalibrating both units from the beginning, this time assured I was in 20:1, both units work perfectly with the GR meter in dot mode. However, when I bridge the pads for bar mode, the entire GR meter lights up, both in GR IN or OUT, and when compressing, GR is shown by LEDs going out from 0 down, not coming on. So my GR bar mode is still acting funny (my VU bar mode had always been fine). I have a video of this behavior if it would help to see.

So sorry I overlooked my ratio settings - I thought I had them in 20:1 the first time around. But I still have odd behavior in bar mode, so hopefully this can be worked out easily. Thank you for your patience and help!

That sounds normal if I understand you correctly.

Think of it as an analog 1176 meter. With GR OFF, or GR on with no signal the needle sits at zero. So in bar mode, the LEDs would be all lit up to zero. Than as you compress on the analog meter the needle moves down or back to the left, so on the LED meter the lights turn off moving down as you compress.

We've done it different than most, thinking of the LED meter how an analog 1176 meter works.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Musepro on October 04, 2016, 01:57:54 PM
That sounds normal if I understand you correctly.

Think of it as an analog 1176 meter. With GR OFF, or GR on with no signal the needle sits at zero. So in bar mode, the LEDs would be all lit up to zero. Than as you compress on the analog meter the needle moves down or back to the left, so on the LED meter the lights turn off moving down as you compress.

We've done it different than most, thinking of the LED meter how an analog 1176 meter works.

Mike

Mike,

Ah! See, I was expecting the GR bar mode to work the same as my FC526s, or any other LED GR meter. I didn't realize you intentionally designed the GR bar meter to work that way - it's an interesting take - I'll have to see now whether I prefer dot or bar for GR (I prefer bar for VU, this much I know). My Western Dynamo 19-09s use dot metering and while they sound awesome, I prefer bar metering - it's just what my eyes are accustomed to seeing.

Glad it's all sorted out and the only problem was my lack of diligence in assuring my ratio switch was at 20:1 with the knobs off. When I went through the calibration steps and checked each setting, I thought they were 20:1. I only realized I had calibrated in SLAM once the units were assembled and the front panel and knobs were on, which I commented about, missed that detail, and you caught!

I owe you coffee or beer or something!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: DonnieDarko on October 13, 2016, 06:14:36 AM
Hey guys,

I´m having some problems with a recent Rev D FET 500 i build.

Before that, I build a Rev F Fet 500 and several Rack Rev D and A. Never a problem beside a faulty output transformer on my first Rev A.

When feeding in a 1khz test tone, the audio (or voltage) doesn´t come tru. DMM reads about 0.003 on output. When turning QBias Adjustment, this varies between 0.001 and 0.003 at max.

The LEDs are set to Bar mode. The compression LEDs somehow decrease when turning the QBias adjust clockwise.

The Output LEDs don´t light up at all.

When pushing hardware Bypass, signal is audible or readable as unity gain when measuring with DMM.

Witougth hardware bypass, no signal can be heard, even when cranking Input and Output, and it measures 0.003 V at max.

I doublechecked all components.

Also resoldered everything on main pcb and meter pcb.

The only thing odd on my build is a smaller electrolytic replacement cap on C7 (They forgot that on in the kit). Smaller meaning: It is in a smaller form factor, of course it´s rated correctly  1µf @50v.  So this should work fine.

The unit makes odd noises when touching the output pot, it definitely reacts to touching this one - but it can´t be wiggled or held in a way that current/signal will pass trough, it just makes noise.

Any suggestions? Faulty output pot? Output Transformer?

Thanks guys!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 13, 2016, 11:45:03 AM
Hey guys,

I´m having some problems with a recent Rev D FET 500 i build.

Before that, I build a Rev F Fet 500 and several Rack Rev D and A. Never a problem beside a faulty output transformer on my first Rev A.

When feeding in a 1khz test tone, the audio (or voltage) doesn´t come tru. DMM reads about 0.003 on output. When turning QBias Adjustment, this varies between 0.001 and 0.003 at max.

The LEDs are set to Bar mode. The compression LEDs somehow decrease when turning the QBias adjust clockwise.

The Output LEDs don´t light up at all.

When pushing hardware Bypass, signal is audible or readable as unity gain when measuring with DMM.

Witougth hardware bypass, no signal can be heard, even when cranking Input and Output, and it measures 0.003 V at max.

I doublechecked all components.

Also resoldered everything on main pcb and meter pcb.

The only thing odd on my build is a smaller electrolytic replacement cap on C7 (They forgot that on in the kit). Smaller meaning: It is in a smaller form factor, of course it´s rated correctly  1µf @50v.  So this should work fine.

The unit makes odd noises when touching the output pot, it definitely reacts to touching this one - but it can´t be wiggled or held in a way that current/signal will pass trough, it just makes noise.

Any suggestions? Faulty output pot? Output Transformer?

Thanks guys!

Something is bad in your two main gain stages. It could be a transformer or pot, but that would be rare. More likely it's a bad joint, misplaced component, or damaged component.

You need to trace through and try to find the error.

If you can, clear some space in your rack (if you don't have a jig) and try the following:

IN/OUT: mid way
att/release: full CW
GR OFF: Selected so the LED is lit
BYPASS: Unselected so LED is NOT lit
Ratio:20

Feed a 1K 0dbu signal into the unit.

Clip the common lead of your dmm to anode (+) side of D4. Then with the unit on (careful, please use mini-grabber leads so you're not reaching in) and getting the signal, measure for AC V at:

C1:
C7:
C8:
Output tx BRN:

Post your AC results. For the capacitors it doesn't matter which lead. They should both be basically the same.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: DonnieDarko on October 14, 2016, 06:46:34 AM
Hey Mike,

Thank you for the quick help!

There go my measurements:

C1: 0.085
C7: 2.76
C8: 0.014
Output tx BRN: 2.784

Most of the meauring Points you named cause a huge humming when measuring.

The solder points under the output pot are extremely sensitive. When touching one of them, the humm/voltages go crazy.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 14, 2016, 11:06:10 AM
seems like something might be off with your output pot.

Is it solder well? Do those three pads look damaged?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: DonnieDarko on October 14, 2016, 11:38:34 AM
I doublechecked, soldered it out, cleaned everything, soldered it in again. Measured it, seems fine and working.

Still very sensitive when touching stuff in in this section.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: DonnieDarko on October 15, 2016, 05:32:41 PM
I meant the pot seems to work correctly - unit still doesn´t pass audio.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 16, 2016, 12:33:39 PM
Hard to say, maybe a bad pot, but that would be super weird. You could try a new one.

email us.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Houroftower on December 12, 2016, 06:13:20 PM
Hi,
While desoldering a resistor in R48, I unfortunately also removed the eyelet from the top (silkscreened) side of the pcb during removal.
The eyelet remains intact on the underside of the pcb.
I have checked for continuity between the intact eyelet on the underside and the next point on the pcb and it appears there is continuity.
What do you recommend for my next step? Can/should I just solder the resistor in, and then verify continuity again, or do I require a repair to the "top" side eyelet in R48 before I proceed?
Thanks.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on December 12, 2016, 08:16:03 PM
Hi,
While desoldering a resistor in R48, I unfortunately also removed the eyelet from the top (silkscreened) side of the pcb during removal.
The eyelet remains intact on the underside of the pcb.
I have checked for continuity between the intact eyelet on the underside and the next point on the pcb and it appears there is continuity.
What do you recommend for my next step? Can/should I just solder the resistor in, and then verify continuity again, or do I require a repair to the "top" side eyelet in R48 before I proceed?
Thanks.
When you write "eyelet" I'll assume you mean "pad" meaning the annular ring of metal surrounding the hole that the component passes through. R48 is a different component for the A, D revs and the F, but in each case there is no top track that it connects to. So you should be OK.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Houroftower on December 12, 2016, 08:28:24 PM
Yes, I was referring to the annular metal ring/pad. It is a Rev D build.  Thanks for your assistance.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: sebperry on December 31, 2016, 05:07:07 PM
Hi there,

I was about halfway through the calibration process for my FET 500 Rev D when I realized that I had a problem and would not be able to complete the process.

I noticed during the Q bias adjustment that I could not get up to 11DBU or 2.75 VAC. The highest I could really get was closer to 5 or 6 DBU. However, I completed the Q bias  adjustment anyway hoping the problem would sort itself out. Obviously, when it came time to calibrate the peak light I couldn't even get close to 16dbu. The problem seems to be in the output stage, though I suppose it could be anywhere?

I've double checked the soldiers and everything seems alright, any help would be much appreciated!!

seb
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on January 01, 2017, 05:26:51 AM
I was about halfway through the calibration process for my FET 500 Rev D when I realized that I had a problem and would not be able to complete the process.

I noticed during the Q bias adjustment that I could not get up to 11DBU or 2.75 VAC. The highest I could really get was closer to 5 or 6 DBU. However, I completed the Q bias  adjustment anyway hoping the problem would sort itself out. Obviously, when it came time to calibrate the peak light I couldn't even get close to 16dbu. The problem seems to be in the output stage, though I suppose it could be anywhere?

I've double checked the soldiers and everything seems alright, any help would be much appreciated!!
Of the things listed in the FAQ linked from the first post, what have you tried so far?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: sebperry on January 01, 2017, 04:31:07 PM
mnats,

Good point, I will double check the resistor values and reflow questionable soldier points and see if that makes a difference.

Thanks
Title: Calibration issue
Post by: Houroftower on January 03, 2017, 11:49:48 AM
Hi,

I have completed my Rev D build and attempted to successfully calibrate a few times but I continue to run into the same problem.

I am using a DMM and a DAW to calibrate.

To date I have visually verified that all components are correct on both the meter board and the main pcb.
I have redone the solder joints that to my eye could have any issue.

But the problem continues at the same step of the calibration process everytime.
So I think I need some guidance on locating where I have either caused damage,  have a faulty component - or some other issue.

Here is my problem:

Calibration (in dot mode) goes well until the final step -- Gain Reduction Tracking.

I zero the meter, using the zero adjust trim pot to get the -1db light on. The red slam light is off at this point.

The problem essentially begins once I deactivate the GR Off switch.

Once I start raising the input level -- The lights, from top to bottom, including the red slam light become lit up, and stay lit (bar mode style I suppose) as I increase the input.  It is not behaving in dot mode anymore from this point on.
The unit passes audio but to my ear it sounds like attack, release and ratio knobs have little to no effect.
I will only add that all trim pots were zeroed prior to calibration, I have verified that I am calibrating in 20:1 mode and I do have a test jig.
Thanks in advance for your help. If I can describe the problem more clearly, or if a picture or video would help, let me know.
Title: Re: Calibration issue
Post by: mnats on January 04, 2017, 05:13:00 PM
Once I start raising the input level -- The lights, from top to bottom, including the red slam light become lit up, and stay lit (bar mode style I suppose) as I increase the input.  It is not behaving in dot mode anymore from this point on.
Just so I understand correctly, both the top gain reduction meter and the lower audio level meters operate in dot mode exactly when? Because if GR Off is active then the top meter shouldn't change at all. You have no connections between the bar mode pins?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Houroftower on January 04, 2017, 05:42:09 PM
Hi,

Both meters should be in dot mode, there is nothing connecting the bar mode pins.
Until the final calibration step both do appear to be functioning properly in dot mode.

I'm good up until this point: https://youtu.be/xIbD-NCo-v4?t=812 (https://youtu.be/xIbD-NCo-v4?t=812)

Then when I get to this point: https://youtu.be/xIbD-NCo-v4?t=872 (https://youtu.be/xIbD-NCo-v4?t=872)

...I increase the input level -- and instead of seeing  individual led's lighting up one by one on the top meter they begin to light up in a bar from red to green to yellow. They stay lit as the input level increases. When I decrease the input level this bar recedes until there is just the "0" green led lit as it was in the first youtube link and the red slam light is off. The bottom meter stays in dot mode.

So if I were to continue on to the NEXT step where we do Tracking Adjust and get the yellow -9 led lit...I would have a bar of lights all the way up to the top red slam led instead of the single -9 led lit.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 04, 2017, 11:42:41 PM
Hi,

Both meters should be in dot mode, there is nothing connecting the bar mode pins.
Until the final calibration step both do appear to be functioning properly in dot mode.

I'm good up until this point: https://youtu.be/xIbD-NCo-v4?t=812 (https://youtu.be/xIbD-NCo-v4?t=812)

Then when I get to this point: https://youtu.be/xIbD-NCo-v4?t=872 (https://youtu.be/xIbD-NCo-v4?t=872)

...I increase the input level -- and instead of seeing  individual led's lighting up one by one on the top meter they begin to light up in a bar from red to green to yellow. They stay lit as the input level increases. When I decrease the input level this bar recedes until there is just the "0" green led lit as it was in the first youtube link and the red slam light is off. The bottom meter stays in dot mode.

So if I were to continue on to the NEXT step where we do Tracking Adjust and get the yellow -9 led lit...I would have a bar of lights all the way up to the top red slam led instead of the single -9 led lit.

Hmmmm.  You;ve gone through all of the meter parts for value, orientation, and solder? 
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Houroftower on January 05, 2017, 06:13:44 AM
Yes I have.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 05, 2017, 04:45:59 PM
Can you post a video of the issue?  I just can't really visualize it.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Houroftower on January 05, 2017, 04:53:10 PM
No problem. I'll post something to Youtube and PM you the link.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 05, 2017, 04:55:27 PM
No problem. I'll post something to Youtube and PM you the link.

Email me the link "info (at) hairballaudio (dot) com"
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on January 05, 2017, 04:58:42 PM
...I increase the input level -- and instead of seeing  individual led's lighting up one by one on the top meter they begin to light up in a bar from red to green to yellow. They stay lit as the input level increases. When I decrease the input level this bar recedes until there is just the "0" green led lit as it was in the first youtube link and the red slam light is off. The bottom meter stays in dot mode.
The more accurate your fault descriptions are, the better advice you'll receive. Previously you wrote "Once I start raising the input level -- The lights, from top to bottom, including the red slam light become lit up, and stay lit..." Now you've written that the bottom meter stays in dot mode. My question is what happens to the red slam light? That is part of the output level metering on the bottom.

The Gain Reduction meter on the top simply measures the DC voltage coming from the main PCB. The GR Off switch allows a portion of the audio signal to reach the GR Control Amp when inactive. So it would be interesting to know what signal the meter board is receiving. Put an oscilloscope probe on pin one of CN200, the board to board connector. Show us what the signal looks like.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Houroftower on January 05, 2017, 05:54:34 PM
I do see how my descriptions could be confusing and sincerely appreciate your responses.
I'm going to proceed with a video and the measurement you requested tonight after work.

By Pin 1, I assume you mean the one labelled "GR Sig"?
I do not have an oscilloscope. I am using a DMM.


Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on January 05, 2017, 07:35:32 PM
I do not have an oscilloscope. I am using a DMM.
I'm guessing you have a computer with an audio input. I hear there is software...

Not directed just to you but I do much better when my questions are answered so please try.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Gosha Usov on January 05, 2017, 08:49:48 PM
Hi, Just finished building Fet/500 Rev A. Got to the first stage of calibrating and my Qbias trim does not adjust the levels turning all the way clockwise or counterclockwise. Is this a faulty trim pot or are there any other components that could cause this.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on January 05, 2017, 09:09:32 PM
Hi, Just finished building Fet/500 Rev A. Got to the first stage of calibrating and my Qbias trim does not adjust the levels turning all the way clockwise or counterclockwise. Is this a faulty trim pot or are there any other components that could cause this.
There is no way to know from your description. Have you read the troubleshooting FAQ linked from the first post of this thread? If not, you may want to start there...
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Houroftower on January 05, 2017, 11:10:47 PM
I'm guessing you have a computer with an audio input. I hear there is software...

Not directed just to you but I do much better when my questions are answered so please try.

I wasn't aware that a PC and audio input could be turned into an oscilloscope, I'll certainly look into it. I should have worded my last message better -- I only meant to say that I am limited to the use of a multimeter at the moment.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hynek on January 08, 2017, 12:18:46 AM
Hello--

Is there a fine gentleman here with a well calibrated FET500RevD v2.0 who could measure a few DC voltages relative to AGND (neg probe on the input TRF shielding can might be easiest) for me?
I'm having some difficulties calibrating the stereo pair I bought from Hairball. More specifically the GR meters.

All three voltages are easily readable off of the 10-pin SIL that connects the two boards.
I'm interested in:
- pin#3 (I understand this is supposed to be -9V)
- pin#1 (Sig) @ 0dB of GR
- pin#1 (Sig) @ 9dB of GR

My Sig @ 9dB of GR goes negative - i.e. below REF LOW of IC204 - which concerns me.

Thanks a lot
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on January 10, 2017, 04:47:15 AM
Hello--

Is there a fine gentleman here with a well calibrated FET500RevD v2.0 who could measure a few DC voltages relative to AGND (neg probe on the input TRF shielding can might be easiest) for me?
I'm having some difficulties calibrating the stereo pair I bought from Hairball. More specifically the GR meters.

All three voltages are easily readable off of the 10-pin SIL that connects the two boards.
I'm interested in:
- pin#3 (I understand this is supposed to be -9V)
- pin#1 (Sig) @ 0dB of GR
- pin#1 (Sig) @ 9dB of GR

My Sig @ 9dB of GR goes negative - i.e. below REF LOW of IC204 - which concerns me.

Thanks a lot
I would never describe myself like that, but I'm happy to post measurements since I have a prototype handy. For what it's worth I can't recall any significant differences to the v2.0; IIRC this was the first version where we'd sorted all the bugs out.

Pin 3: -8.8v
Pin 1, GR off: 1.14v
Pin 1, 9dB of GR: 0.46v

Hope that helps.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hynek on January 10, 2017, 09:22:45 AM
I would never describe myself like that, but I'm happy to post measurements since I have a prototype handy. For what it's worth I can't recall any significant differences to the v2.0; IIRC this was the first version where we'd sorted all the bugs out.

Pin 3: -8.8v
Pin 1, GR off: 1.14v
Pin 1, 9dB of GR: 0.46v

Hope that helps.

Many thanks, mnats--

Yep, all's good on my end except when slowly increasing Input in GR mode there's a point where the GR meter takes a sudden plunge and my Sig goes through the floor even though the audio side measures and sounds fine. At this point I'm pretty certain both of my Q11 are shot as everything around IC1 looks good.

It took me days of reviewing my soldering to figure it out as I was hesitant to believe both units had the same component failure. Wild luck would have it though.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on January 10, 2017, 04:46:41 PM
Many thanks, mnats--

Yep, all's good on my end except when slowly increasing Input in GR mode there's a point where the GR meter takes a sudden plunge and my Sig goes through the floor even though the audio side measures and sounds fine. At this point I'm pretty certain both of my Q11 are shot as everything around IC1 looks good.

It took me days of reviewing my soldering to figure it out as I was hesitant to believe both units had the same component failure. Wild luck would have it though.
That sounds unlikely. If you have built two simultaneously there is a possibility an error was duplicated in each. Still, it wouldn't take long to swap out each FET to prove your hypothesis.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hynek on January 10, 2017, 07:16:29 PM
That sounds unlikely. If you have built two simultaneously there is a possibility an error was duplicated in each. Still, it wouldn't take long to swap out each FET to prove your hypothesis.

Bought as a pair but built consecutively.

Can't disagree with it being unlikely but there doesn't seem to be all that much to that part of the circuit and I've measured and value verified everything to death. Mike is kindly sending another pair of 5457s so I'll know end of the week what my hypothesis amounts to.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hynek on January 15, 2017, 10:13:06 PM
That sounds unlikely. If you have built two simultaneously there is a possibility an error was duplicated in each. Still, it wouldn't take long to swap out each FET to prove your hypothesis.

Thanks for your assistance. Both babies work as a charm and sound very nice.

If anyone cares for a few observations I made through the build

- for my situation 1k5 for R222 worked better than the supplied 1k2, with 1k2 I ended up maxing out VR2 when calibrating
- google for something like "SPDT 1P2T 2 Position 3 Pin PCB Slide Switch" if you wish to have dot/bar modes selectable solderlessly
- I consider standoffs for the meter board a must especially if you plan on ever using the stereo link, you will be pushing on the meter board with the 3.5mm TSR jack that is only held in place by the 10-pin SIL connector, if your top side standoff interferes with any heat sink you may have on Q6 then at least fit the bottom side standoff, it is mechanically the more crucial of the two anyway
- aesthetically, you may prefer to cut the pot shafts shorter and grind the pot nuts smaller to make them fit and hide in the bottom of the knobs, it will allow you to slide the knobs closer to the front panel and only leave a small gap which you may find pleasing to the eye
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mnats on January 16, 2017, 02:44:59 PM
Thanks for your assistance. Both babies work as a charm and sound very nice.
The issue was the FETs as you thought it was?
If anyone cares for a few observations I made through the build

- for my situation 1k5 for R222 worked better than the supplied 1k2, with 1k2 I ended up maxing out VR2 when calibrating
- google for something like "SPDT 1P2T 2 Position 3 Pin PCB Slide Switch" if you wish to have dot/bar modes selectable solderlessly
- I consider standoffs for the meter board a must especially if you plan on ever using the stereo link, you will be pushing on the meter board with the 3.5mm TSR jack that is only held in place by the 10-pin SIL connector, if your top side standoff interferes with any heat sink you may have on Q6 then at least fit the bottom side standoff, it is mechanically the more crucial of the two anyway
- aesthetically, you may prefer to cut the pot shafts shorter and grind the pot nuts smaller to make them fit and hide in the bottom of the knobs, it will allow you to slide the knobs closer to the front panel and only leave a small gap which you may find pleasing to the eye
Thanks for the suggestions. For what it's worth, I never intended the meter to be used in bar mode as it pushes the current consumption too close to the maximum spec. Should have left the pads off but they were on the proto and never got removed. Standoffs are on my BOM and I agree are required. Using the heatsink I did one fin just needs to be bent to clear the top one. I'd love to have a milled panel and custom nuts but that would push the price up too much! Please post a pic of your solution if you get a chance.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hynek on January 16, 2017, 08:58:49 PM
The issue was the FETs as you thought it was?Thanks for the suggestions. For what it's worth, I never intended the meter to be used in bar mode as it pushes the current consumption too close to the maximum spec. Should have left the pads off but they were on the proto and never got removed. Standoffs are on my BOM and I agree are required. Using the heatsink I did one fin just needs to be bent to clear the top one. I'd love to have a milled panel and custom nuts but that would push the price up too much! Please post a pic of your solution if you get a chance.

Yes. It was the FETs and I'm pretty sure I heat-damaged them when soldering. I've gone through spools of solder in my day but I admittedly did a hasty job this time. Looking back, I very much did the best I could to smoke them. Soldered at my "do it all" temperature which I would have still gotten away with had I not soldered all pins at a time and, to make things worse, I pushed the transistors pretty deep which left only short leads to dissipate heat on its fatal march to end the FET's life.

Towards the end of my several days of diagnosing the problem I was confident it was the FETs. Mike was kind enough to send both pairs so I just replaced all four and calibration was a breeze.

As far as bar vs dot, reducing current through the LEDs takes one resistor swap. Naturally, that will also reduce the meter brightness. Anyone who loves the bar mode and is concerned about maxing out supply may want to consider that.

I had no standoffs included in my kit and I quickly resolved to buy some after seeing what I was up  against from mechanical standpoint.

The supplied circular double-disc sink was not a great selection as it was not only interfering with the added standoff but also gently sticking out of the overall footprint of the module. Nothing two minutes on a grinder couldn't fix. I ended up grinding the side of the standoff itself a tad too to reconcile the whole territory dispute.

What I did with the nuts was nothing artistic. I just ground all corners making the hexagon a 12-sided shape small enough to get absorbed by the knob.

I will post photos as soon as the mini switches show up in the mail and I can finally call the whole thing finished.

Impressed with the sound so far!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: useme2305 on January 25, 2017, 06:37:24 AM
https://www.youtube.com/watch?v=Gcmoc6XUo6I

is this behavior in BAR mode correct? i mean, the fact that all leds are lit when no gain reduction is happening and unlighting downwards as the gain reduction increases? kinda weird. or is this normal?
it's basically reverse of what i expected it to be and i just wanna know if this is intended.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hynek on February 03, 2017, 12:04:43 AM
The issue was the FETs as you thought it was?Thanks for the suggestions. For what it's worth, I never intended the meter to be used in bar mode as it pushes the current consumption too close to the maximum spec. Should have left the pads off but they were on the proto and never got removed. Standoffs are on my BOM and I agree are required. Using the heatsink I did one fin just needs to be bent to clear the top one. I'd love to have a milled panel and custom nuts but that would push the price up too much! Please post a pic of your solution if you get a chance.

OK, it's all done and dusted.

This first picture shows the added nylon standoffs. A 6mm one on the bottom between the L-bracket and the main PCB, and a 20mm in between the PCBs. I also used 6mm standoffs on top instead of just nuts after I repeatedly bumped into one of the electrolytic caps on the meter PCB when trying to insert the module into the rack in between two other modules. This way the standoffs will take the beating instead.

You can also see the trimmed output transistor sink. More importantly, and I admittedly didn't do a great job of capturing that detail, the sink also has a chunk ground out of it on the side facing the standoff. The standoff itself is gently shaven too. That gave me a decent size gap but not enough to use aluminum standoffs and risk fatal issues.

I would have loved to actually screw the bottom standoff to the L-bracket as that would further stiffen the structure and the thread is already there but I didn't find any place to source the correct screws. Drilling the hole in the L-bracket just deep enough may also prove to be more challenging then what it looks like.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hynek on February 03, 2017, 12:17:15 AM
The issue was the FETs as you thought it was?Thanks for the suggestions. For what it's worth, I never intended the meter to be used in bar mode as it pushes the current consumption too close to the maximum spec. Should have left the pads off but they were on the proto and never got removed. Standoffs are on my BOM and I agree are required. Using the heatsink I did one fin just needs to be bent to clear the top one. I'd love to have a milled panel and custom nuts but that would push the price up too much! Please post a pic of your solution if you get a chance.

...this one shows the trimmed pot nuts to make way for the knobs to sink deeper on the shafts and closer to the face plate.

The little metal bit in the forefront isn't dirt, it's a piece I made that's the same shape as the negative space that's missing from the ratio selection switch shaft. I use it every time with builds that have that issue. A little bit of work but it makes the knob sit a lot nicer when tightening the set screw.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hynek on February 03, 2017, 12:22:14 AM
The issue was the FETs as you thought it was?Thanks for the suggestions. For what it's worth, I never intended the meter to be used in bar mode as it pushes the current consumption too close to the maximum spec. Should have left the pads off but they were on the proto and never got removed. Standoffs are on my BOM and I agree are required. Using the heatsink I did one fin just needs to be bent to clear the top one. I'd love to have a milled panel and custom nuts but that would push the price up too much! Please post a pic of your solution if you get a chance.

...and finally with the knobs on and a better view of the added micro switches to select between the LED meter modes.

Now let's make music!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Rickstar44 on February 04, 2017, 01:06:54 PM
Hello
I just purchased three FET/500 Compressors and am very happy with the kits, one problem.. I am a novice builder and started with the Rev A build. I have been over the build sheet and schematic sheet several times and cant seem to find anything out of place. all my solders seem to be good, every cap and diode and relay in the right direction. I could use some advise on next step "short of sending it to hairball and pay the $100 to fix it" the PK light stays lit and the GR light will not work. Trying to calibrate and no signal out to my DIMM. I have a Purple sweet 10 rack, Pro tools 12 with the signal generator set to 1000Hz  -18dB, Fluke 179 Meter. If there were more discussions I would be happy to  keep plugging along but....
Thanks
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: sebperry on February 12, 2017, 01:11:44 PM
I posted maybe a month ago about some issues I've been having calibrating my Rev D.

My problems all seem to stem from the output stage. I can't get enough signal out of the unit to calibrate properly.  Most I can seem to get with Qbias maxed out is 1.367 VAC. And this is with the output pot fully clockwise.

The reason I think it's with the OUTPUT stage is because my input meters are in the red early on, but my output meters barely register until I turn the output pot fully clockwise.

I doublechecked all my resistors, questionable soldiers, I'm worried that the problem lies with the output transformer because I had some problems soldiering that one and it's not the neatest job (I trimmed some of the wires a little too short).

Are there any measurements I can take to isolate the issue?

Many thanks!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on February 16, 2017, 10:48:09 PM
I posted maybe a month ago about some issues I've been having calibrating my Rev D.

My problems all seem to stem from the output stage. I can't get enough signal out of the unit to calibrate properly.  Most I can seem to get with Qbias maxed out is 1.367 VAC. And this is with the output pot fully clockwise.

The reason I think it's with the OUTPUT stage is because my input meters are in the red early on, but my output meters barely register until I turn the output pot fully clockwise.

I doublechecked all my resistors, questionable soldiers, I'm worried that the problem lies with the output transformer because I had some problems soldiering that one and it's not the neatest job (I trimmed some of the wires a little too short).

Are there any measurements I can take to isolate the issue?

Many thanks!

Try removing Q1 if you can. Carefully.

Then see what kind of output you get.  You won't be able to adjust the Q, but this can confirm if there is an issue with your FET.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: cspears on February 23, 2017, 11:05:21 PM
Hi Gang,
Just got my 500 Revision F soldered and am waiting on a jig to arrive to do more tests. For the meantime, I have some very obvious faults that I thought perhaps one of you kind folks might be able to answer:

1. The unit passes signal but doesn't compress when powered on and it doesn't pass any signal at all when the bypass is activated! The input and output knobs do change the volume, though.

2. I did power the unit on with a whole bunch of cables, (in lieu of the jig coming in the mail) and was able to trace the audio signal using the Marc Burnley technique until I arrived at R6 at which point the signal died and I couldn't hear it anywhere else on the board.

3. Visually, it looks like I connected the VR1 and VR2 backward though they only fit in one direction into the pcb (they are currently not changing the meters).

Anyways, apologies for my DIY nubeness and if someone has a quick solution to the bypass situation I would be very grateful. I attached a pic.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on February 24, 2017, 01:15:08 PM
Hi Gang,
Just got my 500 Revision F soldered and am waiting on a jig to arrive to do more tests. For the meantime, I have some very obvious faults that I thought perhaps one of you kind folks might be able to answer:
1. The unit passes signal but doesn't compress when powered on and it doesn't pass any signal at all when the bypass is activated! The input and output knobs do change the volume, though.

That's super weird. Double check all of the soldering around the bypass switch for shorts.

2. I did power the unit on with a whole bunch of cables, (in lieu of the jig coming in the mail) and was able to trace the audio signal using the Marc Burnley technique until I arrived at R6 at which point the signal died and I couldn't hear it anywhere else on the board.

This is in bypass mode where your signal dies?

That MAY indicate a FET issue.  You could try removing Q1 and seeing if that allows your signal to pass.

3. Visually, it looks like I connected the VR1 and VR2 backward though they only fit in one direction into the pcb (they are currently not changing the meters).
Anyways, apologies for my DIY nubeness and if someone has a quick solution to the bypass situation I would be very grateful. I attached a pic.

That's fine.  They will work fine like that.  You're issue is probably no ouput or something else in the meter.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: sebperry on February 26, 2017, 12:07:08 PM
Hi Mike,
I removed Q1 and the unit seems to be behaving pretty  much the same. One thing I noticed that was weird was that at I turn the output pot clockwise I get no signal at all until it's turned about 3/4 to the right... If you have any other ideas please share, otherwise I think I will be sending it in for repair.

I posted maybe a month ago about some issues I've been having calibrating my Rev D.

My problems all seem to stem from the output stage. I can't get enough signal out of the unit to calibrate properly.  Most I can seem to get with Qbias maxed out is 1.367 VAC. And this is with the output pot fully clockwise.

The reason I think it's with the OUTPUT stage is because my input meters are in the red early on, but my output meters barely register until I turn the output pot fully clockwise.

I doublechecked all my resistors, questionable soldiers, I'm worried that the problem lies with the output transformer because I had some problems soldiering that one and it's not the neatest job (I trimmed some of the wires a little too short).

Are there any measurements I can take to isolate the issue?

Many thanks!

Try removing Q1 if you can. Carefully.

Then see what kind of output you get.  You won't be able to adjust the Q, but this can confirm if there is an issue with your FET.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on February 27, 2017, 09:49:43 AM
That indicates and issue with your gain stages.

For now, keep the unit in GR Off and keep Q1 out.  That way we can focus on just getting the gain stages working right.

Check all of your solder, components, and continuity in the two gain sections. Those parts are largely between the pots and output transformer. Especially make sure you don't have a bad joint, or something like a 470Ω and 470KΩ swapped.

Its the components in the top half of the schematic:
http://mnats.net/files/FET-D500.pdf

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: JoelCoteBergevin on April 02, 2017, 12:19:08 AM
Ok so my FET/500 rev D pair has been going strong for months but now I have a new chassis (Chameleon Labs 880 rack) and I'm having a weird issue..  I use the compressors as hardware inserts in my DAW and if I send a signal to FET #1, Fet#2's gain reduction meter is active (doing the same thing as FET #1) but the link 1/8 cable is NOT connected. I tried the compressors in every possible position in the chassis with the same result.

At first, I thought it had to do with the chassis (or some channel cascading embedded, but no) and after testing I realised it was not the issue. Because if I remove FET #1 from the chassis and send a signal to FET #1, FET#2's meter is not moving (which is normal since I send no signal through but only to where the #1 would be.

It's only really just the gain reduction meter. When I don't send a signal the unit #2, the knobs or output meter do nothing (which is normal), but the gain reduction meter is doing the exact same thing as on FET #1 (which is the only one getting signal)

In short: I only send a signal to one of my FET/500 but the other one (not getting signal) is showing the exact same gain reduction metering info. Like if they were linked, but they are not.

Thoughts?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 02, 2017, 12:35:12 AM
Ok so my FET/500 rev D pair has been going strong for months but now I have a new chassis (Chameleon Labs 880 rack) and I'm having a weird issue..  I use the compressors as hardware inserts in my DAW and if I send a signal to FET #1, Fet#2's gain reduction meter is active (doing the same thing as FET #1) but the link 1/8 cable is NOT connected. I tried the compressors in every possible position in the chassis with the same result.

At first, I thought it had to do with the chassis (or some channel cascading embedded, but no) and after testing I realised it was not the issue. Because if I remove FET #1 from the chassis and send a signal to FET #1, FET#2's meter is not moving (which is normal since I send no signal through but only to where the #1 would be.

It's only really just the gain reduction meter. When I don't send a signal the unit #2, the knobs or output meter do nothing (which is normal), but the gain reduction meter is doing the exact same thing as on FET #1 (which is the only one getting signal)

In short: I only send a signal to one of my FET/500 but the other one (not getting signal) is showing the exact same gain reduction metering info. Like if they were linked, but they are not.

Thoughts?

Chassis pin 6s are surely linked.  Look at the end of the FET/500 build guide.
If pin 6s are linked units are permanently linked.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: JoelCoteBergevin on April 02, 2017, 11:19:02 AM
Thank you so much ! Makes a lot of sense since this lunchbox also has DB25 connectors (just like the newer API chassis). I should've checked into the build guide before asking the question. 

However, from what I understand, in the chassis, channel 1 and 2 are stereo linked, same for 3 and 4, 5 and 6, 7 and 8, etc. But even if I rack the FET/500 in channel 1 for example and the second FET/500 in channel 5 for example, they appear to be linked anyway. Could it be that ALL channels are linked in my lunchbox? In that case should I just remove all 0 ohm resistors?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 02, 2017, 11:22:58 AM
Thank you so much ! Makes a lot of sense since this lunchbox also has DB25 connectors (just like the newer API chassis). I should've checked into the build guide before asking the question. 

However, from what I understand, in the chassis, channel 1 and 2 are stereo linked, same for 3 and 4, 5 and 6, 7 and 8, etc. But even if I rack the FET/500 in channel 1 for example and the second FET/500 in channel 5 for example, they appear to be linked anyway. Could it be that ALL channels are linked in my lunchbox? In that case should I just remove all 0 ohm resistors?

Could be yes. Just use an ohm meter and test the all pin 6's like at the bottom of the guide.

Unplug your unit for safety, no need to power it for the test.

Has to be that all pin 6's are linked.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Riverjetty on April 28, 2017, 04:22:07 PM
Hello All,

Little help--I just finish stuffing my fet/500 1176 rev. D from Hairball but neglected to set the trimpots at the get go.  I am now callibrating, is this a problem?

Please help and thanks in advance,
rj
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 28, 2017, 04:25:43 PM
Hello All,

Little help--I just finish stuffing my fet/500 1176 rev. D from Hairball but neglected to set the trimpots at the get go.  I am now callibrating, is this a problem?

Please help and thanks in advance,
rj

You can center the 20 turn trim pots by rotating them until you hear a little "click". That is the end. Then rotate back 20 turns in the opposite direction.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Riverjetty on April 28, 2017, 04:55:59 PM
Thanks Mike.  Pardon--Which, out of the three, are the "20 turn trimpots?" 

Thanks,
rj
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 28, 2017, 05:00:53 PM
Thanks Mike.  Pardon--Which, out of the three, are the "20 turn trimpots?" 

Thanks,
rj

The ones that seem to turn endlessly. The short square ones with the white plastic dials are single turn.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Riverjetty on April 28, 2017, 05:09:30 PM
Thanks, at this time, I'm only turning white screws or do I also turn the copper coloured screws to center position as well?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 30, 2017, 11:53:45 AM
Thanks, at this time, I'm only turning white screws or do I also turn the copper coloured screws to center position as well?

Are you following the calibration videos in the build guide?

Generally you want to center all of the trimmers except the Qbias. You set that for max output to start.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: 12afael on May 20, 2017, 03:28:04 PM
I wonder if someone have a Mouser BOM for rev D or F ( or both)? I´m in the middle of doing one for revF .
I was trying to create a  excel bom from the pdf but I have had problems with that.  From text or excel file is easy but from the pdf is not.

best regards
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: TDJ on May 21, 2017, 04:56:44 PM
Hey guys! First time post so I'm sorry if this isn't the correct place, forgive my ignorance. I've searched and cant seem to find the solution to my problem. I just finished my 2nd Hairball blue stripe. I have a strange problem on my 2nd one - when I go from 20:1 to 4:1 it stops compressing. If I switch from 8:1 or 12:1 to 4:1 it compresses! So, there's something fishy about my 4:1 that I can't seem to figure out. Double check resistor values on my ratio board? Any help would be greatly appreciated. Thanks!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 22, 2017, 01:53:44 PM
Hey guys! First time post so I'm sorry if this isn't the correct place, forgive my ignorance. I've searched and cant seem to find the solution to my problem. I just finished my 2nd Hairball blue stripe. I have a strange problem on my 2nd one - when I go from 20:1 to 4:1 it stops compressing. If I switch from 8:1 or 12:1 to 4:1 it compresses! So, there's something fishy about my 4:1 that I can't seem to figure out. Double check resistor values on my ratio board? Any help would be greatly appreciated. Thanks!

Bad solder joint or pad around those 4:1 resistors.

Is this 500 series or rack?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: TDJ on May 22, 2017, 02:55:58 PM
Rack! I will reflow joints on the ratio board!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 22, 2017, 07:18:31 PM
Rack! I will reflow joints on the ratio board!

Post any follow up to this thread:

https://groupdiy.com/index.php?topic=63600.0
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mdmitch2 on May 23, 2017, 07:25:08 PM
Hey guys, I just built a pair of Fet500 Rev A's, and may be observing a little bit of strange behavior. On both units, when using VU trim to set the -10 LED, I don't get any change across the full range of adjustment (with the DMM reading 0.388 volts). The LED is in fact already at -10, and it just stays there. I noticed that if I lower the voltage with the output knob to 0.350 volts, then the LED drops down to -20 and I can then use the VU trim to bring it back up to -10. I'm using a Fluke 87v, and I double checked voltages with another DMM, and they match. Any thoughts?

Note, I built a Fet 500 when they first came out, and I don't remember having this issue, but I do think that the PCB has since been revised, so maybe this is normal?

Also, I noticed that the kit came with 2N3707 transistors for Q3, Q5, whereas the BOM states 2N3708. These seem to be pretty comparable, so I didn't worry about it....
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 25, 2017, 03:57:15 PM
Hey guys, I just built a pair of Fet500 Rev A's, and may be observing a little bit of strange behavior. On both units, when using VU trim to set the -10 LED, I don't get any change across the full range of adjustment (with the DMM reading 0.388 volts). The LED is in fact already at -10, and it just stays there. I noticed that if I lower the voltage with the output knob to 0.350 volts, then the LED drops down to -20 and I can then use the VU trim to bring it back up to -10. I'm using a Fluke 87v, and I double checked voltages with another DMM, and they match. Any thoughts?

Hmmm try setting it at +4 which would be the first orange LED. Set your output to 1.25VAC. You should see the trimmer adjust it up and down an LED around +4. It's not a huge adjustment range.

Note, I built a Fet 500 when they first came out, and I don't remember having this issue, but I do think that the PCB has since been revised, so maybe this is normal?

Maybe. I usually do it at +4...however the lower you do the adjustment on the scale, the more accurate the meter will be (per the meter chip datasheet).

Also, I noticed that the kit came with 2N3707 transistors for Q3, Q5, whereas the BOM states 2N3708. These seem to be pretty comparable, so I didn't worry about it....

Nope that is fine.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: leoaudio13 on May 27, 2017, 07:33:19 AM
Hi,
I just completed my Rev A 500 build. All are working find except i have some difficulties with the Gain reduction tracking pot. Gotta try to reset it again according to posts here.
Unfortunately, The bypass switch does not work at all. Even it is in bypass mode, the LED didnt light up. Tried to check with DMM, LED working fine. With SW3, measured continuity is fine while in Bypass and out of bypass mode. Any suggestions please ? Much appreciate.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 27, 2017, 11:40:59 AM
Hi,
I just completed my Rev A 500 build. All are working find except i have some difficulties with the Gain reduction tracking pot. Gotta try to reset it again according to posts here.
Unfortunately, The bypass switch does not work at all. Even it is in bypass mode, the LED didnt light up. Tried to check with DMM, LED working fine. With SW3, measured continuity is fine while in Bypass and out of bypass mode. Any suggestions please ? Much appreciate.

SW3 requires a functioning LED to work. Make sure the LED is soldered in the correct orientation and it is making contact with the solder pads.

Some times it looks soldered, but if you wiggle it you can see a leg is floating off the pad.

Mike

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: leoaudio13 on May 27, 2017, 09:52:30 PM
SW3 requires a functioning LED to work. Make sure the LED is soldered in the correct orientation and it is making contact with the solder pads.

Some times it looks soldered, but if you wiggle it you can see a leg is floating off the pad.

Mike

Thank you Mike! It was the LED that made the SW3 to stop. All is good now. Gonna order Rev F soon ! ;)
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: leoaudio13 on May 28, 2017, 05:20:37 AM
My attack and release knobs are in reverse order ( left for long time and right for shorter time ). Is that normal at all ?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mdmitch2 on May 29, 2017, 08:43:33 AM
Hmmm try setting it at +4 which would be the first orange LED. Set your output to 1.25VAC. You should see the trimmer adjust it up and down an LED around +4. It's not a huge adjustment range.

Maybe. I usually do it at +4...however the lower you do the adjustment on the scale, the more accurate the meter will be (per the meter chip datasheet).

Nope that is fine.

Thanks, that did the trick --- no issues when setting at +4 (the LED moved between -1,0,1).
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 30, 2017, 01:59:03 PM
My attack and release knobs are in reverse order ( left for long time and right for shorter time ). Is that normal at all ?

Normal for this style compressor yes.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: blueberryjam on May 31, 2017, 04:27:17 AM
hey guys,

Not being a DIY-er myself I decided to order a pair of FET 500 model D off someone who builds them on ebay. Upon receiving them I've rapidly noticed that both unit's  VU-Meters don't behave the same way, and are not showing the same gain reduction levels when fed the same material (I'm not sure whether this is only a VU issue).

So I started (trying) to recalibrate, and noticed that on one unit, several gain reduction LEDs light up at the same time, as if the meters were set to bar mode (but they are not). The other unit meter seemed to be working properly in dot mode, but just a minute ago it switched to bar mode all of a sudden ! So I'm starting to think I ordered the units off the wrong guy :(

Is there something I could do by myself to try and identify the issue ? (I know how to use a DMM, and not much else) Or would I be better off sending them to be repaired ?

cheers !
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on June 01, 2017, 01:35:24 PM
hey guys,

Not being a DIY-er myself I decided to order a pair of FET 500 model D off someone who builds them on ebay. Upon receiving them I've rapidly noticed that both unit's  VU-Meters don't behave the same way, and are not showing the same gain reduction levels when fed the same material (I'm not sure whether this is only a VU issue).

So I started (trying) to recalibrate, and noticed that on one unit, several gain reduction LEDs light up at the same time, as if the meters were set to bar mode (but they are not). The other unit meter seemed to be working properly in dot mode, but just a minute ago it switched to bar mode all of a sudden ! So I'm starting to think I ordered the units off the wrong guy :(

Is there something I could do by myself to try and identify the issue ? (I know how to use a DMM, and not much else) Or would I be better off sending them to be repaired ?

cheers !

Hmmmm. Hard to say. Definitely sounds like a meter issue. On the GR meter usually only one LED lights up at a time.

I remember seeing behavior like that in repairs, but I can't remember the solution. A good place to start is to make sure the PCB, especially the edge connectors are VERY clean and free of flux. You can scrub the bottom liberally with isopropyl alcohol.

Also look at the build map and confirm all of the components on the meter board are in the right place.

Make sure you're calibrating with a sine wave and not pink noise.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: blueberryjam on June 03, 2017, 01:29:00 AM
Thanks for the help Mike ! Will try and see if I can find the issue this week-end.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: blueberryjam on June 13, 2017, 11:29:30 AM
hey ! Me again !

As advised I started cleaning the pcb boards. They were pretty dirty indeed. The seller who built the unit had used a lot of flux, so when I used the isopropyl alcohol the flux spread out and the pcbs became very very sticky. It took me hours to clean them properly.  :'(

When I plugged them back both unit seemed to behave properly, so today I started calibrating again. It went fine at first, then at one point when calibrating the VU I noticed that the leds were moving when I touch the attack knob (Not moving it, just touching it with my hand). Right after that, the problem came back and the first 5 leds of the GR meter would light up at the same time in GR ON mode. Would that give us any clues about what the issue could be ?

Decided to do some more cleaning because the pcb was still a bit sticky where the leds are connected. Will plug it back and test again tomorrow.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on June 13, 2017, 11:33:41 AM
hey ! Me again !

As advised I started cleaning the pcb boards. They were pretty dirty indeed. The seller who built the unit had used a lot of flux, so when I used the isopropyl alcohol the flux spread out and the pcbs became very very sticky. It took me hours to clean them properly.  :'(

When I plugged them back both unit seemed to behave properly, so today I started calibrating again. It went fine at first, then at one point when calibrating the VU I noticed that the leds were moving when I touch the attack knob (Not moving it, just touching it with my hand). Right after that, the problem came back and the first 5 leds of the GR meter would light up at the same time in GR ON mode. Would that give us any clues about what the issue could be ?

Decided to do some more cleaning because the pcb was still a bit sticky where the leds are connected. Will plug it back and test again tomorrow.

Not really. Probably some ground buzz. That's not normal but may resolve when the unit is in the bracket with faceplate/nuts installed.

You can give it a pretty good soak.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: blueberryjam on June 17, 2017, 06:47:29 AM
Thanks Mike.

Did some more cleaning and was finally able to calibrate both units ! They seem to be working fine now, except that one unit still had that "bug" once ; it's meters flicked then switched to bar mode when I touched the attack pot. I turned off and on the 500 series chassis and it went back to working properly.

Been thinking about switching the knobs for the FET style ones you have for sale in the parts store. I'm thinking that since the sides are plastic and non conductive, that should keep me for having that issue again. Both my ratio knobs screws are stripped anyway so i could use a replacement.

Would the FET Style Miniature Knob 1/8" Shaft fit the FET 500 series ?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on June 20, 2017, 12:33:54 AM
Thanks Mike.

Did some more cleaning and was finally able to calibrate both units ! They seem to be working fine now, except that one unit still had that "bug" once ; it's meters flicked then switched to bar mode when I touched the attack pot. I turned off and on the 500 series chassis and it went back to working properly.

Been thinking about switching the knobs for the FET style ones you have for sale in the parts store. I'm thinking that since the sides are plastic and non conductive, that should keep me for having that issue again. Both my ratio knobs screws are stripped anyway so i could use a replacement.

Would the FET Style Miniature Knob 1/8" Shaft fit the FET 500 series ?

Conductivity isn't your issue, at least with the knobs.  Make sure the pot nuts are tight against faceplate. You should not be getting buzz or meter flicker when you touch the knobs. That's a ground error somewhere in the system/unit.  Using plastic knobs may stop it, but it's still an issue that may pop up in other ways.

But yes those knobs would fit.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Blackdawg on July 02, 2017, 07:23:00 PM
Hey guys,

I just built 2 REV F FET500s. Great kits!

My issue is that both of my VU meters are fully lit when i turn them on..on both kits. None of the trim pots seem to do anything. Im using a Lindell 510 rack.

Going through the meter PCB now to double check stuff. Just seems odd that both are doing that.

Any tips??

Thanks!

Monte
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on July 03, 2017, 01:42:16 PM
Hey guys,

I just built 2 REV F FET500s. Great kits!

My issue is that both of my VU meters are fully lit when i turn them on..on both kits. None of the trim pots seem to do anything. Im using a Lindell 510 rack.

Going through the meter PCB now to double check stuff. Just seems odd that both are doing that.

Any tips??

Thanks!

Monte

The VU part of the GR part of the meter?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Blackdawg on July 04, 2017, 03:35:53 AM
The VU part of the GR part of the meter?

Yeah the top half of the meter. Lights up completely. It'll slowly light up till all of the LEDS are lit. I did put the jumper in for Bar Mode. It also lights up from the bottom up..as in the yellows light up first and then goes up to green.

The other odd thing i notice is my Grayhill switch. If i line up the knob with the notch it does not point to the correct labels on the silk screen. It is way off. I set the switch up as per the instructions though. Do I just tighten down the knob so the set screw isn't on the flat part?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on July 05, 2017, 11:46:06 AM
Yeah the top half of the meter. Lights up completely. It'll slowly light up till all of the LEDS are lit. I did put the jumper in for Bar Mode. It also lights up from the bottom up..as in the yellows light up first and then goes up to green.

The other odd thing i notice is my Grayhill switch. If i line up the knob with the notch it does not point to the correct labels on the silk screen. It is way off. I set the switch up as per the instructions though. Do I just tighten down the knob so the set screw isn't on the flat part?

As far as the silkscreen/knob, that's just knob placement. I usually set it at SLAM with no issue. I deal you want to avoid the flat part.

For GR meter,  start by setting the trimmers associate with that adjustment dead center. Turn them until you hear a click, then rotate back 10 full turns and they will be centered.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Blackdawg on July 05, 2017, 06:56:47 PM
As far as the silkscreen/knob, that's just knob placement. I usually set it at SLAM with no issue. I deal you want to avoid the flat part.

For GR meter,  start by setting the trimmers associate with that adjustment dead center. Turn them until you hear a click, then rotate back 10 full turns and they will be centered.

Mike

Thanks for the response. Will give it a go. I had set all the trim pots dead center via my Ohm Meter. But sounds like something is off. So i'll give it ago!

Monte
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Blackdawg on July 05, 2017, 07:38:42 PM
That helped! Thanks!

Also why does it work backwards? I thought the greens would have lit first from the top down.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on July 06, 2017, 12:25:34 PM
That helped! Thanks!

Also why does it work backwards? I thought the greens would have lit first from the top down.

The GR meter? It's like the anolog meter on the original. Starts at zero and moves down.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: alexgriva on July 06, 2017, 02:30:14 PM
Hi Guys

I'm having an issue with GR meter calibration (Rev D). Looks fine when is 20:1. When I change to any other ratio the meter goes red/peak. Any idea?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Blackdawg on July 11, 2017, 04:24:47 AM
The GR meter? It's like the anolog meter on the original. Starts at zero and moves down.

Right, 0 being on top and -22 being on the bottom. Mine lights up at -22 first and goes up...

Also, been trying to calibrate. Nothing seems to change when trying to do the Q bias. Hell i can't even get it to output 2.75v even. Im getting 0.0168v max. And when i crank the input and outputs i only get 0.03v..
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Blackdawg on July 11, 2017, 05:11:21 AM
figured out my problem. My outputs and inputs from the HP 8920A are BNC and i made cables from BNC to XLR. Had one of the wires going to ground not + & -

Edit: Damn. My VU meter trim pot does nothing. VR1.

I set the output to 4.88v and my peak LED is already peaked and lit up. Doesn't have enough in it at all to change it.  In fact if I change the output so the meter is reading in the green the pot only lowers it one LED.

Also, i can hit 45v output now..seems kinda high..
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Blackdawg on July 16, 2017, 01:32:20 PM
Hello?? Any input? Very much would like these to work soon..
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: robsn on July 17, 2017, 07:48:08 AM
Hi,

I'm building a rev A stereo pair and can't calibrate the meters to -10 dB. What's the exact trimmer type of VR2? I can find 25 different 2kΩ bourns pots that would fit the footprint. Hope 2k will do the job.

Or would it make more sense to change either R222 or R223? I'm fully ccw on the pot.

Cheers, Rob
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on July 17, 2017, 10:09:13 AM
Hi Guys

I'm having an issue with GR meter calibration (Rev D). Looks fine when is 20:1. When I change to any other ratio the meter goes red/peak. Any idea?

Give it some time to warm up, then use the zero adjust on the front to get the meter in the right spot. Should settle after 2-3 seconds on all ratios.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on July 17, 2017, 10:12:04 AM
Hi,

I'm building a rev A stereo pair and can't calibrate the meters to -10 dB. What's the exact trimmer type of VR2? I can find 25 different 2kΩ bourns pots that would fit the footprint. Hope 2k will do the job.

Or would it make more sense to change either R222 or R223? I'm fully ccw on the pot.

Cheers, Rob

The Rev F is a little finicky with the peak transistor.  DO you have any resistors in house? Lowering R203 should fix your issue.  Try something around 90Kish.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: robsn on July 17, 2017, 01:44:24 PM
The Rev F is a little finicky with the peak transistor.  DO you have any resistors in house? Lowering R203 should fix your issue.  Try something around 90Kish.

Mike

Possibly something got mixed up here. I'm building a Rev A, not F and VR2 is the issue. R203 is around VR1.
But yes I do have a resistor set :)

Cheers, Rob
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Blackdawg on July 18, 2017, 03:08:38 AM
Possibly something got mixed up here. I'm building a Rev A, not F and VR2 is the issue. R203 is around VR1.
But yes I do have a resistor set :)

Cheers, Rob

I think the tip for lower R203 was for me...but not sure..

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: robsn on July 18, 2017, 03:48:44 PM
Anyhow. On one unit I was fully ccw on both VR1 and VR2. So I made these adjustments on both. It's a stereo pair  ::):


I can now calibrate the meters and both VR1 and VR2 pots are pretty much midway on both units.

I'd be extremely happy if someone who actually knows what he's doing could confirm that:

Cheers, Rob

PS get rid of that recaptcha stuff. It has stolen me like half an hour today and yesterday due to my inability to check street signs, connection timeouts and google accusing me of being a robot and not letting me select the loudspeaker symbol.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Blackdawg on July 18, 2017, 06:44:16 PM
Anyhow. On one unit I was fully ccw on both VR1 and VR2. So I made these adjustments on both. It's a stereo pair  ::):

  • I changed R203 from 22k0 to 24k0.
  • I changed R222 from 1k2 to 1k8.

I can now calibrate the meters and both VR1 and VR2 pots are pretty much midway on both units.

I'd be extremely happy if someone who actually knows what he's doing could confirm that:

  • I didn't make something completely stupid by changing these resistors i.e. it doesn't have any negative impact on any parts or the sound and I'm not outside the range of the voltage dividers total ranges (I hope this sentence makes sense).
  • I didn't have to repeat setting the Q bias after changing these resistors 'cause I didn't  :P
  • It didn't have an impact on the tracking adjust because I had to adjust it on one unit and it is fully ccw. I did't have to change it on the second compressor where I made the same resistor changes.
Cheers, Rob

PS get rid of that recaptcha stuff. It has stolen me like half an hour today and yesterday due to my inability to check street signs, connection timeouts and google accusing me of being a robot and not letting me select the loudspeaker symbol.

Im doing Rev F but i lowered my 203 to 98k and that got me good. Then i read your post and raised 222 to 1.4k as its all i had and that helped my VR1 pot too.

Im not the guy to tell you if that is going to cause problems though but i can't imagine it would. Just raised the resistance on the meter circuit.

Thanks for the tip too!

I have 1 calibrated before i switch R222. So i'll see after i change it if my q bias is different.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on July 19, 2017, 10:31:34 PM
I think the tip for lower R203 was for me...but not sure..

For Rev F's only.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Blackdawg on July 20, 2017, 12:43:17 AM
For Rev F's only.

Awesome.

Got mine all calibrated. Gonna use em tomorrow!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: jcgriggs on September 17, 2017, 09:27:03 AM
Greetings,

Tried to post this yesterday, but got messed up by the Captcha stuff - apologies if it is a duplicate.

During de-soldering I lost the solder pad on the PCB for pin 5 of the input transformer on one of my Rev D builds (long story).

I looked at the data sheet for the part (http://library.hairballaudio.com/datasheets/3837.pdf), the schematic (http://mnats.net/files/FET-D500.pdf) and the PCB itself, but I can't work out where this pin should connect to.

Can someone tell me which other pad I could jump pin 5 of the input transformer to to restore the circuit?

Thanks,
   John
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 18, 2017, 12:07:29 PM
Greetings,

Tried to post this yesterday, but got messed up by the Captcha stuff - apologies if it is a duplicate.

During de-soldering I lost the solder pad on the PCB for pin 5 of the input transformer on one of my Rev D builds (long story).

I looked at the data sheet for the part (http://library.hairballaudio.com/datasheets/3837.pdf), the schematic (http://mnats.net/files/FET-D500.pdf) and the PCB itself, but I can't work out where this pin should connect to.

Can someone tell me which other pad I could jump pin 5 of the input transformer to to restore the circuit?

Thanks,
   John

Pin 5 goes to the ground.  Same as pin 6 right beside it.  Just solder a jumper wire from pin 5 to pin 6.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: stevelawaudio on September 21, 2017, 01:56:24 AM
Hi Everyone -
This is my first Fet/500/D build. Successfully built a Fet/Rack/A, which I'm loving!

Im having trouble getting my Gain Trims and VU to work. I successfully got the Q-Bias setup, but now when I move the Gain and VU  trim pots I have no movement of LEDs at all.
Ive been back across the bill of materials and cross checked things.. still no joy.

Where should i be starting my hunt.?

Cheers..
Steve.

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 21, 2017, 11:30:34 AM
Hi Everyone -
This is my first Fet/500/D build. Successfully built a Fet/Rack/A, which I'm loving!

Im having trouble getting my Gain Trims and VU to work. I successfully got the Q-Bias setup, but now when I move the Gain and VU  trim pots I have no movement of LEDs at all.
Ive been back across the bill of materials and cross checked things.. still no joy.

Where should i be starting my hunt.?

Cheers..
Steve.

Are any of the LEDs lighting?

Are you passing signal?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: stevelawaudio on September 21, 2017, 07:08:16 PM
Are any of the LEDs lighting?

Are you passing signal?

Mike


Hey Mike -

Yep, got signal in and out, and the LEDS are lighting. They just won't move with the trim pots. Turned the trims fully each way, and no luck/movement.

thanks mate!

S.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: stevelawaudio on September 21, 2017, 07:45:15 PM
Are any of the LEDs lighting?

Are you passing signal?

Mike

Hey Mike -

just been across it with a DMM - found a few values that are correct in colour banding but are reading a bit low.
examples -
R207 (100k) is reading 72k
R216, R213, R215 (100k) are reading 80k
R227 (10k) is 5.3k...etc..
there are a few more reading low too..

thanks for your help!

S.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: stevelawaudio on September 22, 2017, 12:55:04 AM
Hi All -

I've done some more testing and found the following..

If i drop the output control down, to around +5dBu i can adjust the LEDs up and down the meter.
When I set the output back to +16dBu, I have no movement in either direction up or down.


s.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: jcohen on September 22, 2017, 02:24:55 AM
Hello! I've just finished my first FET500 Rev A build. Everything went great and seemed to be in order until calibration time. When I went to calibrate the unit, the qbias didn't seem to be making a difference (turning either way would alternate my multimeter from 0.016 to 0.017 VAC). Also putting my output to full still only yielded me at most about 0.800 VAC whereas the video was showing more that 2 VAC. All my reading seemed to be low, then about 10 minutes in, I heard a nice frightening POP. Immediately turned the unit off and removed it to find that the 100 uF 50V cap in C4 spot had blown it top up a bit. Don't want to plug the unit back in until I can diagnose what would do such a thing. Any ideas what might have gone wrong? I did a full look over and don't see any parts installed other than instructed by schematic. Below is a picture of the C4 cap that has blown.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 22, 2017, 01:04:23 PM
Hey Mike -

just been across it with a DMM - found a few values that are correct in colour banding but are reading a bit low.
examples -
R207 (100k) is reading 72k
R216, R213, R215 (100k) are reading 80k
R227 (10k) is 5.3k...etc..
there are a few more reading low too..

thanks for your help!

S.

You can't really measure resistors in circuit without lifting a leg or understanding the math of parallel resistance.  Many will read low as they are now in parallel with other resistors.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 22, 2017, 01:05:28 PM

Hey Mike -

Yep, got signal in and out, and the LEDS are lighting. They just won't move with the trim pots. Turned the trims fully each way, and no luck/movement.

thanks mate!

S.

Do you have the right value trimmers in the correct spots?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: stevelawaudio on September 22, 2017, 06:36:36 PM
You can't really measure resistors in circuit without lifting a leg or understanding the math of parallel resistance.  Many will read low as they are now in parallel with other resistors.

Mike

Ok. Thought it would be something like that.

Do you have the right value trimmers in the correct spots?

Yeah, 10k at VR1 and 1k at VR2.

Any ideas of why it works at a lower voltage?

Thanks.!
S.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 25, 2017, 02:05:54 PM
Ok. Thought it would be something like that.

Yeah, 10k at VR1 and 1k at VR2.

Any ideas of why it works at a lower voltage?

Thanks.!
S.

Are the all illuminated at higher v?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: stevelawaudio on September 26, 2017, 12:25:58 AM
Are the all illuminated at higher v?

As i increase the output each LED lights up as it goes up.
Then when it hits around +6 it gets to the LED209 and stays there. I can't get Peak (LED210) to light.

Then as I wind up the output to +16, the 209 LED stays lit, and the trim doesn't change anything.

I drop the output to around +2 and then i can adjust the LEDs 2 or 3 LEDs.

Can i email you a little video.?

Thanks Mike!

Steve.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on September 26, 2017, 11:51:57 AM
As i increase the output each LED lights up as it goes up.
Then when it hits around +6 it gets to the LED209 and stays there. I can't get Peak (LED210) to light.

Then as I wind up the output to +16, the 209 LED stays lit, and the trim doesn't change anything.

I drop the output to around +2 and then i can adjust the LEDs 2 or 3 LEDs.

Can i email you a little video.?

Thanks Mike!

Steve.

I don't think a video would help.

Really it comes down to:

1. Misplaced component
2. Damaged component
3. Bad solder joint
4. Damaged pad/trace
5. Backwards/unsoldered LEDs - wiggle the LEDs make sure both legs are connected.

Go through all they and report back.

Does the GR metering work?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Catrunes on November 29, 2017, 02:49:52 PM
Hi all, one of the 2 rev D fet 500 kits I built will not reduce gain more than 1-2 db no matter what i do to it. The other unit I built works perfectly as intended. There is one thing you should know though, when i first built faulty unit, i had reversed one of the power filtering electros and i had to replace it, is there any chance i blew a fet or something? any help is appreciated. thank you max
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 30, 2017, 12:19:16 PM
Hi all, one of the 2 rev D fet 500 kits I built will not reduce gain more than 1-2 db no matter what i do to it. The other unit I built works perfectly as intended. There is one thing you should know though, when i first built faulty unit, i had reversed one of the power filtering electros and i had to replace it, is there any chance i blew a fet or something? any help is appreciated. thank you max

Probably a GR Amp issue.  Is the over all gain (in GR OFF) the same as the other one?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Catrunes on December 02, 2017, 03:44:01 AM
Yes it acts the same as the functional unit in gr off mode. Gain seems fine
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on December 04, 2017, 01:45:01 PM
Yes it acts the same as the functional unit in gr off mode. Gain seems fine

I would check everything in your GR Amp section (vertical resistors back corner) and resistors by your grayhill switch.

Calibration went fine?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mdmitch2 on January 22, 2018, 07:54:30 PM
I'm trying to figure out why the gain reduction on/off LED isn't working.... I've built probably 8 of these, and this is the first time I've encountered this issue.

Basically, when I first built the unit (rev D), everything worked fine except the LED didn't turn on when I engaged the switch. However, the switch worked as you would expect, just no light from the LED. I checked that it was in the correct orientation, and also checked it with my multimeter, and just for good measure, swapped it with one of the meter LEDs. When I re-assembled, it still would not light up (and the swapped meter LED was fine). So I proceeded to verify all component values, diode/cap orientation, etc, and everything was correct. Then I reflowed the LED and switches, as well as the relays and ICs, and put it back together.... BINGO it worked as expected, and I was able to calibrate the unit with no issue. THEN, the next day, I powered it up, and no light from the LED again..... everything else works/sounds great.  Any ideas?

Thanks!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 23, 2018, 12:07:03 AM
I'm trying to figure out why the gain reduction on/off LED isn't working.... I've built probably 8 of these, and this is the first time I've encountered this issue.

Basically, when I first built the unit (rev D), everything worked fine except the LED didn't turn on when I engaged the switch. However, the switch worked as you would expect, just no light from the LED. I checked that it was in the correct orientation, and also checked it with my multimeter, and just for good measure, swapped it with one of the meter LEDs. When I re-assembled, it still would not light up (and the swapped meter LED was fine). So I proceeded to verify all component values, diode/cap orientation, etc, and everything was correct. Then I reflowed the LED and switches, as well as the relays and ICs, and put it back together.... BINGO it worked as expected, and I was able to calibrate the unit with no issue. THEN, the next day, I powered it up, and no light from the LED again..... everything else works/sounds great.  Any ideas?

Thanks!

That LED is just a two component circuit.  The LED, R510 and the switch.  I would check for continuity between those three components.  Could be a slightly lifted pad, or even that pole of the switch is weird.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mdmitch2 on January 23, 2018, 10:16:12 AM
That LED is just a two component circuit.  The LED, R510 and the switch.  I would check for continuity between those three components.  Could be a slightly lifted pad, or even that pole of the switch is weird.

Thanks -- that's what I was thinking.... so it seems like a faulty switch is the most likely culprit at this point. Is there a way to test the switch in circuit? I checked continuity between the switch and R510 (see pic), and when the switch is disengaged, I get continuity between the green circled points, and when it's engaged, there is also continuity with the red circled point, and no others.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 24, 2018, 10:56:08 AM
When the button is pushed in, only these should have continuity.

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 24, 2018, 10:58:15 AM
When the button is out, only these should have continuity.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mdmitch2 on January 24, 2018, 02:03:19 PM
When the button is out, only these should have continuity.

The two areas that you circled in blue -- should those have continuity with each other? i.e. between all four points in blue? Mine do not.... but I noticed that all four have continuity on the red led bypass switch.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 24, 2018, 02:06:16 PM
The two areas that you circled in blue -- should those have continuity with each other? i.e. between all four points in blue? Mine do not.... but I noticed that all four have continuity on the red led bypass switch.

Not all 4 points.  Just the two circled. There are 2 separate switches on the switch. They have no relation to each other.

Google DPDT. One switch is the 3 terminals on one side, one switch is the three terminals on the other side. The middle terminal on each side is the common.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 24, 2018, 02:09:13 PM
Look at the gif on the left and imagine that is you pushing the switch in and out.

http://www.zseries.in/electronics%20lab/switches/slide/pictures/working%20of%20dpdt%20slide%20switch.gif

The two sides are isolated.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mdmitch2 on January 24, 2018, 03:37:18 PM
Not all 4 points.  Just the two circled. There are 2 separate switches on the switch. They have no relation to each other.

Google DPDT. One switch is the 3 terminals on one side, one switch is the three terminals on the other side. The middle terminal on each side is the common.

Thanks -- I went ahead and just swapped the two switches, and the problem stayed with the yellow LED. I also pulled the resistor and resoldered the LED for probably the third time (having also swapped it once already). I also checked it with the diode meter, and it seems fine, and it lights up a little with the DMM.  I also pulled and tested R510....


So if it's not related to one of those three components.....?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mdmitch2 on January 25, 2018, 05:10:37 PM
Not all 4 points.  Just the two circled. There are 2 separate switches on the switch. They have no relation to each other.

Google DPDT. One switch is the 3 terminals on one side, one switch is the three terminals on the other side. The middle terminal on each side is the common.

Are there test points that may be instructive for diagnosing this? I checked voltage at the LED, and the cathode is showing 15.75 volts, and when the switch is engaged, R510 is getting 31.5 volts.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 25, 2018, 08:33:19 PM
Are there test points that may be instructive for diagnosing this? I checked voltage at the LED, and the cathode is showing 15.75 volts, and when the switch is engaged, R510 is getting 31.5 volts.

Has to be a bad pad.

Check out "SW1G$2" on the right.

http://mnats.net/files/FET-A500.pdf

Just 3 components in series.  One of those traces is dead.

Mike

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mdmitch2 on January 26, 2018, 08:50:58 PM
Has to be a bad pad.

Check out "SW1G$2" on the right.

http://mnats.net/files/FET-A500.pdf

Just 3 components in series.  One of those traces is dead.

Mike

I connected R510 directly to the LED with a spare resistor leg, and that solved the problem.

Thanks for your help!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 27, 2018, 01:41:04 PM
I connected R510 directly to the LED with a spare resistor leg, and that solved the problem.

Thanks for your help!

Nice.  8)
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: hiegdk on March 06, 2018, 02:18:47 AM
Hi there, this is my first FET 500 build (Rev D) but I've built a bunch of Lolas. I'm having an issue with the GR meter. I have both meters in DOT mode. The 'SLAM' LED (LED220 I believe) is constantly lit regardless of the ratio setting and I can't seem to get any of the other GR LEDs to light up during the GR meter calibration steps. I've tried setting the trim pots to their center points but so far no adjustment has resulted in any change in the GR meter (SLAM LED stays lit, no other LEDs activate).

The Q-bias adjustment seemed to work as expected and the VU calibration went smoothly as well. I've cleaned the boards real good and reflowed a few solder points that looked dull.

Anyone have any advice?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 08, 2018, 11:23:46 AM
Hi there, this is my first FET 500 build (Rev D) but I've built a bunch of Lolas. I'm having an issue with the GR meter. I have both meters in DOT mode. The 'SLAM' LED (LED220 I believe) is constantly lit regardless of the ratio setting and I can't seem to get any of the other GR LEDs to light up during the GR meter calibration steps. I've tried setting the trim pots to their center points but so far no adjustment has resulted in any change in the GR meter (SLAM LED stays lit, no other LEDs activate).

The Q-bias adjustment seemed to work as expected and the VU calibration went smoothly as well. I've cleaned the boards real good and reflowed a few solder points that looked dull.

Anyone have any advice?

I don't have a lot of test point advice on those. It is important that you center all trimmers.  Go over all of you component values and soldering.  Also, check the section on the main PCB related to GR metering. It's the stuff around the IC (make sure that IC is the correct value). Also make sure all points of the 10 pin connector are soldered well.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 08, 2018, 01:41:05 PM
Hello,

I've just finished building my 1176 Rev A 500 comp and have problem when calibrate It.

I have a lot of noise coming out of the comp -18Db (less when the output is fully clockwise). I Have noise even when I send nothing to the 1176.
A very low signal compared to what I send to the comp (when bypass It).

I'll check this with a friend of mine but If you have any idea ;-) This could be a shortcut ;-)

Thanks a lot for your support and your Job at Hairball!!!
Antoine

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: hiegdk on March 10, 2018, 06:52:45 PM
I don't have a lot of test point advice on those. It is important that you center all trimmers.  Go over all of you component values and soldering.  Also, check the section on the main PCB related to GR metering. It's the stuff around the IC (make sure that IC is the correct value). Also make sure all points of the 10 pin connector are soldered well.

Thanks.  I've confirmed all the values around IC1 and double checked the soldering in that area and all seems fine. When I put the GR meter in BAR mode with the 0 adjust and Tracking adjust at their halfway points, input and output at midway, attack and release all the way up and ratio at 20:1 all of the LED in the GR meter are lit up including the SLAM LED. Not sure if that help narrow it down or not. At this point I'm at a loss as to what to try next.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: denov on March 11, 2018, 10:28:57 PM
my qBais doesn't seem to be doing anything to the output.  i see change on my multi meter when i move the in and out pots.  the LEDs for the meter light up while during CCW but the voltage on the meter doesn't change.   where/what should i start looking at?

thanks
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 12, 2018, 09:56:07 PM
my qBais doesn't seem to be doing anything to the output.  i see change on my multi meter when i move the in and out pots.  the LEDs for the meter light up while during CCW but the voltage on the meter doesn't change.   where/what should i start looking at?

thanks

What is your output level (in VAC or dB)?

If you have a Rev A  make sure you have the link wire in the ROPT1 spot.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 12, 2018, 09:59:20 PM
Thanks.  I've confirmed all the values around IC1 and double checked the soldering in that area and all seems fine. When I put the GR meter in BAR mode with the 0 adjust and Tracking adjust at their halfway points, input and output at midway, attack and release all the way up and ratio at 20:1 all of the LED in the GR meter are lit up including the SLAM LED. Not sure if that help narrow it down or not. At this point I'm at a loss as to what to try next.

With the 20 turn trimmers, it can take a bit to get it into the proper range. With the zero set midway can you get that meter to trop by turning the tracking adjust to either extreme? Same with putting the tracking center, can you get zero adjust to move it?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 12, 2018, 10:00:39 PM
Hello,

I've just finished building my 1176 Rev A 500 comp and have problem when calibrate It.

I have a lot of noise coming out of the comp -18Db (less when the output is fully clockwise). I Have noise even when I send nothing to the 1176.
A very low signal compared to what I send to the comp (when bypass It).

I'll check this with a friend of mine but If you have any idea ;-) This could be a shortcut ;-)

Thanks a lot for your support and your Job at Hairball!!!
Antoine

Are you able to calibrate it?

Does the QBias change your output?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 15, 2018, 06:26:36 AM
Are you able to calibrate it?

Does the QBias change your output?

Mike

Hello Mike,

can't calibrate It... and the Qbias doesn't seems to change my output...

Is It bad doctor?!!! ;-)

Thanks for your help Mike!!!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 15, 2018, 03:48:49 PM
Hello Mike,

can't calibrate It... and the Qbias doesn't seems to change my output...

Is It bad doctor?!!! ;-)

Thanks for your help Mike!!!

It's a Rev A?

Do you have a link wire in the ROPT1 spot?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 16, 2018, 06:40:07 AM
It's a Rev A?

Do you have a link wire in the ROPT1 spot?

Hello Mike,

It's a REV A and I put the wire in the Ropt1 yes....

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 17, 2018, 12:19:30 AM
Hello Mike,

It's a REV A and I put the wire in the Ropt1 yes....

hmmmmm.

Is it possible for you to safely have the unit and your rack and probe around the top of the PCB with a DMM?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: hiegdk on March 17, 2018, 03:50:12 AM
With the 20 turn trimmers, it can take a bit to get it into the proper range. With the zero set midway can you get that meter to trop by turning the tracking adjust to either extreme? Same with putting the tracking center, can you get zero adjust to move it?

Mike

Tried both, no movement. Could it be possible I cooked a transistor? I've certainly done that before on my Lola builds. If so, which one(s) would be involved?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 18, 2018, 07:33:56 AM
hmmmmm.

Is it possible for you to safely have the unit and your rack and probe around the top of the PCB with a DMM?

Mike

Sounds tricky!!!! ;-)
 Yes!!! I can test the unit outside the rack and check the top PCB... I've got an extension connector for my lunchbox.
It's the one proposed by "soundskulptor" a french company that make preamps like you.

I can check everything going IN and OUT the FET500 Rev A.

Once again, Thanks a lot for your help!!!
Have a nice Sunday

Antoine
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 19, 2018, 12:58:02 PM
Tried both, no movement. Could it be possible I cooked a transistor? I've certainly done that before on my Lola builds. If so, which one(s) would be involved?

There are no transistors. There are actually very few parts in the GR meter. Have a look at the schematic:

http://mnats.net/files/FET-A500.pdf

If you scroll down to the meter schematic, it's just the few parts around IC204. There is that LM317, a trimmer, and few resistors and a cap.

Then on the main schematic, just the few parts around IC1.

So for the GR circuit, there are actually more parts on the main PCB.

Check all those parts.

Do you have another FET/500? To swap meter PCBs?

Mike

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 19, 2018, 01:03:24 PM
Sounds tricky!!!! ;-)
 Yes!!! I can test the unit outside the rack and check the top PCB... I've got an extension connector for my lunchbox.
It's the one proposed by "soundskulptor" a french company that make preamps like you.

I can check everything going IN and OUT the FET500 Rev A.

Once again, Thanks a lot for your help!!!
Have a nice Sunday

Antoine

For this testing, you need to use the ANODE (no line) of D4 as your ground reference (common).

Set your compressor controls:

Input: 12 O’Clock
Output: 12 O’Clock
Attack: GR OFF
Release: Full CW
Ratio: 20:1
Meter: GR
Signal: Sine 1kHz @ 0dBu (0.775 VAC across input + and - or PIN 8 and 10)

What is your ACV and each of the 3 output pot terminals?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 20, 2018, 05:31:32 AM
For this testing, you need to use the ANODE (no line) of D4 as your ground reference (common).

Set your compressor controls:

Input: 12 O’Clock
Output: 12 O’Clock
Attack: GR OFF
Release: Full CW
Ratio: 20:1
Meter: GR
Signal: Sine 1kHz @ 0dBu (0.775 VAC across input + and - or PIN 8 and 10)

What is your ACV and each of the 3 output pot terminals?

Mike

Thanks Mike!!!
I'll try that next week...

I'm just not sure about your settings :

Input: 12 O’Clock                      OK
Output: 12 O’Clock                 OK
Attack: GR OFF                         ???? Attack Full CW???? like in the procedure for calibration
Release: Full CW                      OK
Ratio: 20:1                                   OK
Meter: GR                                    OK
Signal: Sine 1kHz @ 0dBu (0.775 VAC across input + and - or PIN 8 and 10)

Thanks a lot Mike!!!!!
Antoine
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 20, 2018, 12:09:21 PM
Thanks Mike!!!
I'll try that next week...

I'm just not sure about your settings :

Input: 12 O’Clock                      OK
Output: 12 O’Clock                 OK
Attack: GR OFF                         ???? Attack Full CW???? like in the procedure for calibration
Release: Full CW                      OK
Ratio: 20:1                                   OK
Meter: GR                                    OK
Signal: Sine 1kHz @ 0dBu (0.775 VAC across input + and - or PIN 8 and 10)

Thanks a lot Mike!!!!!
Antoine

Of sorry. That knob doesn't matter. Engage the GR OFF switch.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 27, 2018, 09:11:55 AM
Of sorry. That knob doesn't matter. Engage the GR OFF switch.

Hello Mike,

I've put 1khz @ 0Dbu (0,778 VAC direct from my Input XLR before connecting my FET 500 Rev A .

Here's what I got with the FET 500 connected :
- I've re-checked my Input with the FET 500 and found 0,626 VAC

- Between the anode of D4 and PIN 2 (OUT+) decreasing from 0,85 (when only  the com is at D4) to almost nothing
- Between the anode of D4 and PIN 3 (OUT- Lo)  0,850 VAC
- Between the anode of D4 and PIN 2 (OUT+) decreasing from 0,85 (when only  the com is at D4) to almost nothing

I've Re-Checked the Qbias like in the calibration procedure :
- nothing change with the Output between pin 2 and 4
- the LED are moving so I think nothings wrong with the meter PCB

Again... Thanks for your help Mike!!!!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 27, 2018, 01:54:26 PM
What is your DC V at the gate of Q1 as you rotate the Qbias? Use that D4 anode as your common.

https://www.soundtronics.co.uk/images/detailed/23/Ext-2300-298.jpg?t=1482942320

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 28, 2018, 08:53:56 AM
What is your DC V at the gate of Q1 as you rotate the Qbias? Use that D4 anode as your common.

https://www.soundtronics.co.uk/images/detailed/23/Ext-2300-298.jpg?t=1482942320

Mike

I send 0,797VAC in the FET 500 with the [email protected] Dbu (can't found 0,778 like yesterday...)

And found :

from 0 to 2,11 VDC between the gate of Q1 and the anode of D4 when I rotate the Qbias...

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 28, 2018, 01:04:15 PM
I send 0,797VAC in the FET 500 with the [email protected] Dbu (can't found 0,778 like yesterday...)

And found :

from 0 to 2,11 VDC between the gate of Q1 and the anode of D4 when I rotate the Qbias...

Do you mean -2.11 V DC?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 28, 2018, 02:04:55 PM
Do you mean -2.11 V DC?

Sorry!!!!

I found -2,11 V DC exactly
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 28, 2018, 02:06:23 PM
Sorry!!!!

I found -2,11 V DC exactly

If you set it to -2.11 VDC does your unit pass signal?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 28, 2018, 02:22:21 PM
If you set it to -2.11 VDC does your unit pass signal?

Mike

Signal pass yes!!!!

and I'm so sorry It's not -2,11VDC but 2,11VDC...

I'll send you a good bottle of wine for being so helping!!!!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 28, 2018, 02:24:41 PM
Signal pass yes!!!!

and I'm so sorry It's not -2,11VDC but 2,11VDC...

Sorry, try measuring that using the ground pin on the edge card.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 28, 2018, 02:29:22 PM
Sorry, try measuring that using the ground pin on the edge card.

Between Pin 5 (com) and the gate of Q1 I found :

14,33 VDC  (not minus!!! I just double checked this time ) ;-)
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 28, 2018, 03:38:22 PM
Between Pin 5 (com) and the gate of Q1 I found :

14,33 VDC  (not minus!!! I just double checked this time ) ;-)

Sorry, I had to go look at mine to confirm the grounding scheme again. 

What is your DC V at the meter PCB connector pin 3 (labeled -V out) using the Anode of D4 as your common point?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 29, 2018, 06:14:33 AM
Sorry, I had to go look at mine to confirm the grounding scheme again. 

What is your DC V at the meter PCB connector pin 3 (labeled -V out) using the Anode of D4 as your common point?

Mike

I found  between pin 3 (-V out) and D4
- 8,91 VDC
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 29, 2018, 12:36:32 PM
I found  between pin 3 (-V out) and D4
- 8,91 VDC

Excellent. That's perfect.

Now try again at the gate of Q1.  What is your DC V between the gate and D4 as you rotate the QBias pot?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 29, 2018, 04:37:41 PM
Excellent. That's perfect.

Now try again at the gate of Q1.  What is your DC V between the gate and D4 as you rotate the QBias pot?

Same Value :

from 0 DC V  to -2,11 DC V
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 29, 2018, 04:46:26 PM
Same Value :

from 0 DC V  to -2,11 DC V

Perfect. So that is correct.

Your output level should drop as you rotate from -2.11 to 0.  If it's not dropping, but you see your meter drop. My guess is that you don't have a wire link soldered into that OPTR-1 spot....OR Q1 is fried.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 30, 2018, 11:15:36 AM
Perfect. So that is correct.

Your output level should drop as you rotate from -2.11 to 0.  If it's not dropping, but you see your meter drop. My guess is that you don't have a wire link soldered into that OPTR-1 spot....OR Q1 is fried.

Mike

Thanks Mike,

My guess is that Q1 is fried... I'm sure about my wire link...

Is there something special about the 2N5457 ?!!!!

There is two of them at Mouser'shop... which one do I have to buy?!!!! the TO-92 or the TO-92-3...?!

I'll keep you in touch about It.

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 31, 2018, 12:22:33 PM
Thanks Mike,

My guess is that Q1 is fried... I'm sure about my wire link...

Is there something special about the 2N5457 ?!!!!

There is two of them at Mouser'shop... which one do I have to buy?!!!! the TO-92 or the TO-92-3...?!

I'll keep you in touch about It.

Farnell have 3 references....
Which one is the good one?!!!!

Thanks Mike!!!! Have a good week end!!!!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on March 31, 2018, 12:24:19 PM
Farnell have 3 references....
Which one is the good one?!!!!

Thanks Mike!!!! Have a good week end!!!!

We can send you a new matched set if you like. Send us an email.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on March 31, 2018, 01:22:26 PM
We can send you a new matched set if you like. Send us an email.

Mike

Have send you an email with a stupid question about the match pair ;-)
I found my answer in your build guide....

I was a newbie few months ago... and I'm learning little by little ;-)

Thanks a lot for your precious help Mike!!!! Tell me where I can send a bottle of wine ;-)

Have a good week end!!!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: milchmannverleih on April 01, 2018, 11:03:33 AM
Hi you guys,

I have a little problem with the size of the heatsink of Q6. I got a part that looks different from the heatsink you show in the build guide, and unfortunately the Meterboard won't fit in if I put this thing on the transistor.

Did I do it wrong? Do I have to trim it? (pic attached)

Instead of the 2N3708 listed in the BOM I got a 2N3707. I quess it fits, just wanted to make shure before I solder it in and fry it!?

Also C13 as well as Q1 and 11 are missing, so if you have some other heatsink that will fit in, you can send it together with the missing parts!

Phillip
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 01, 2018, 12:41:49 PM
Hi you guys,

I have a little problem with the size of the heatsink of Q6. I got a part that looks different from the heatsink you show in the build guide, and unfortunately the Meterboard won't fit in if I put this thing on the transistor.

Did I do it wrong? Do I have to trim it? (pic attached)

Instead of the 2N3708 listed in the BOM I got a 2N3707. I quess it fits, just wanted to make shure before I solder it in and fry it!?

Also C13 as well as Q1 and 11 are missing, so if you have some other heatsink that will fit in, you can send it together with the missing parts!

Phillip

Ya that's the wrong heatsink. We had a really bad batch of FET/500 kits a few months back, not sure what happened.

We'll get the right stuff out to you. 2N3707 is the correct part now, so use those.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: ninopelo29 on April 30, 2018, 07:16:38 PM
Hi Mike,

I've got two FET 500 Rev D units and I'm having the same issue with both: I cannot calibrate the VU meters as described in the calibration guide and video. Here are the issues:
- I turn the Gain Trim and I cannot get the RED Peak LED to light (I can only get as high as Orange +3)
- I turn VR2 and cannot get the meter to even register in the green, so I can't get it to -10

I checked my trim pots and I have 103 in position VR2 and 102 in position VR1, which is correct. I also have 22k resistors in both R202 and R203 positions.

Both units are built the same way (although built following the instructions at two different times) and both have the same issue.

Any thoughts? Thank you so much for any help!!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 30, 2018, 07:33:37 PM
Hi Mike,

I've got two FET 500 Rev D units and I'm having the same issue with both: I cannot calibrate the VU meters as described in the calibration guide and video. Here are the issues:
- I turn the Gain Trim and I cannot get the RED Peak LED to light (I can only get as high as Orange +3)
- I turn VR2 and cannot get the meter to even register in the green, so I can't get it to -10

I checked my trim pots and I have 103 in position VR2 and 102 in position VR1, which is correct. I also have 22k resistors in both R202 and R203 positions.

Both units are built the same way (although built following the instructions at two different times) and both have the same issue.

Any thoughts? Thank you so much for any help!!

VR1 should be 103 (10K) and VR2 should be 102 (1K). Sounds like you have those backwards?

If that's not is....

If you look at the meter schematic down towards the bottom of this doc:
http://mnats.net/files/FET-D500.pdf

There is a group of components around IC200A and IC200B (which is the two amps in IC200).  Something has to be wrong somewhere in there. Triple check.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: ninopelo29 on April 30, 2018, 08:14:27 PM
VR1 should be 103 (10K) and VR2 should be 102 (1K). Sounds like you have those backwards?

If that's not is....

If you look at the meter schematic down towards the bottom of this doc:
http://mnats.net/files/FET-D500.pdf

There is a group of components around IC200A and IC200B (which is the two amps in IC200).  Something has to be wrong somewhere in there. Triple check.

Mike

*****************
Hi Mike,

Thanks for the quick response.

I checked all the components in the cluster around IC200 (from C200 all the way thru everything connected to Q200) and everything is correct. The trim adjusters were the way you described, too (sorry about my error between VR1 and VR2).

Anything else you recommend I check?

Thank you!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on April 30, 2018, 08:15:53 PM
*****************
Hi Mike,

Thanks for the quick response.

I checked all the components in the cluster around IC200 (from C200 all the way thru everything connected to Q200) and everything is correct. The trim adjusters were the way you described, too (sorry about my error between VR1 and VR2).

Anything else you recommend I check?

Thank you!

Are you sure your sending the correct level to the unit?  Did you watch the calibration video?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: ninopelo29 on May 01, 2018, 08:43:23 PM
Are you sure your sending the correct level to the unit?  Did you watch the calibration video?

Mike

**************

Hi Mike,

Thanks again for your help. That last question unlocked it for me.

I was doing the calibration at 0dBu=0.775v peak-to-peak, which is wrong. It should have been 2.19v peak-to-peak.

Here is a link to a dBu conversion website for anyone else making a dumb mistake like me : http://www.sengpielaudio.com/calculator-db-volt.htm

To those having this issue, if you are checking the input and output signal voltages on an oscilloscope, make sure you are either using the math function to calculate VRMS (0dBu = 0.775VRMS) or use the link above to find the peak-to-peak values for the dBu values.

Thanks again!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 01, 2018, 09:31:53 PM
**************

Hi Mike,

Thanks again for your help. That last question unlocked it for me.

I was doing the calibration at 0dBu=0.775v peak-to-peak, which is wrong. It should have been 2.19v peak-to-peak.

Here is a link to a dBu conversion website for anyone else making a dumb mistake like me : http://www.sengpielaudio.com/calculator-db-volt.htm

To those having this issue, if you are checking the input and output signal voltages on an oscilloscope, make sure you are either using the math function to calculate VRMS (0dBu = 0.775VRMS) or use the link above to find the peak-to-peak values for the dBu values.

Thanks again!

Glad you got it sorted!

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: theodorblumentopf on May 17, 2018, 04:09:15 PM
Hey guys, i hope someone can help me out,
I just finished my 1176 Rev A DIY and everything is working fine, exept the meter when gain reduction is switched.
The unit is compressing but not showing compression on the meter just staying at "0"
Is there anything i can check in the GR/ Meter section on the PCB ?

Thanks a lot
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 17, 2018, 07:17:57 PM
Hey guys, i hope someone can help me out,
I just finished my 1176 Rev A DIY and everything is working fine, exept the meter when gain reduction is switched.
The unit is compressing but not showing compression on the meter just staying at "0"
Is there anything i can check in the GR/ Meter section on the PCB ?

Thanks a lot

So you see a 10 dB drop on the output?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: denov on May 19, 2018, 04:45:44 PM
If you have a Rev A  make sure you have the link wire in the ROPT1 spot.

finally got a chance to get back to this!

this details of the ROPT1 jumper seems to be lacking in the new manuals.    i found the 2nd link via google.

   missing -> http://www.hairballaudio.com/blog/resources/build-guides/fetrack-v2-buildbrstep-2-populating-the-pcbs
   is in -> http://www.hairballaudio.com/blog/resources/build-guides/fet500-build-and-calibration-guide


after adding in the ROPT1 jumper the unit calibrated just fine.   

do i need to do anything if i have a v2 for use in my API cases?  i have one with and one without db25.

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 20, 2018, 12:47:52 PM
finally got a chance to get back to this!

this details of the ROPT1 jumper seems to be lacking in the new manuals.    i found the 2nd link via google.

   missing -> http://www.hairballaudio.com/blog/resources/build-guides/fetrack-v2-buildbrstep-2-populating-the-pcbs
   is in -> http://www.hairballaudio.com/blog/resources/build-guides/fet500-build-and-calibration-guide


after adding in the ROPT1 jumper the unit calibrated just fine.   

do i need to do anything if i have a v2 for use in my API cases?  i have one with and one without db25.

The first link is for the RACK version which does not have the OPT-1.  The second link is for the 500 series version.

You shouldn't have to do anything.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: philwantspro6 on May 29, 2018, 05:56:45 PM
There are a few oddities Ive noticed with my Rev D, but this one is the most persistent.
I applied a .775VAC signal to my RevD, GR OFF.

Using my Fluke metering the output leads, I measured the following....
Input & Output knobs fully CW: 34.8VAC
Input & Output knobs at noon:        ~7VAC
Input & Output knobs fully CCW:     0VAC

PK LED illuminates at 4.8VAC. But that probably has more to do with my initial calibration.

These values seem high to me.

Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on May 30, 2018, 02:42:08 PM
There are a few oddities Ive noticed with my Rev D, but this one is the most persistent.
I applied a .775VAC signal to my RevD, GR OFF.

Using my Fluke metering the output leads, I measured the following....
Input & Output knobs fully CW: 34.8VAC
Input & Output knobs at noon:        ~7VAC
Input & Output knobs fully CCW:     0VAC

PK LED illuminates at 4.8VAC. But that probably has more to do with my initial calibration.

These values seem high to me.

The FET/500 has an intricate grounding system.  The -16VDC rail is actually used at the audio GND on the main PCB.  So if you're measuring voltages on the main PCB you need to use the GND on the PCB not on the chassis or pinout.  Use the + (anode) of D4 as your ground/common probe point and re check.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mcrowe on June 05, 2018, 11:10:46 PM
I’m working on my first rev A build, and I can’t find the stops for the ratio switch. Where should these be, and what do they look like? Is it possible to obtain replacements? Can I substitute something (a resistor leg maybe)?

I also have a second question: I was following the Mnats build guide before I realized there was a Hairball guide. I installed Q6 without the spacer. Is it necessary for thermal reasons, or am I OK without it?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Alsgro on June 06, 2018, 02:04:22 AM
Hi!  I just did this today.  They’re super small, little tiny graphite pieces. And u might’ve thrown them away, because I almost did.  Look for tiny Grey pieces!!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mcrowe on June 06, 2018, 01:33:16 PM
Are they about 1/4" long? I did find one little piece like that in my container of discarded leads.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mcrowe on June 06, 2018, 08:38:16 PM
I dug up the one that I found and judging by how perfectly it fits in the hole, that's definitely the part. Unfortunately the other one is permanently lost, I think. Is there a concern about conductivity here? If not, I'll insert a clipped lead and get on with my life.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Alsgro on June 06, 2018, 09:30:05 PM
Yeah, they look like mechanical pencil lead, about a 1/2 inch or so.

I don’t think they’re conductive, just to stop the pot from spinning all the way around?

I may be wrong.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on June 07, 2018, 01:26:02 PM
We can send you one if you like.

Email us.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mcrowe on June 09, 2018, 12:46:37 PM
Hi Mike,

I will definitely do that. Before I do, I want to give a report about where I am with my build just to make sure there's nothing else I might need.

First, the good news: for the most part, the compressor seems to basically be working. I haven't calibrated it yet, but I sent a drum recording through as a test, and it sounds great. The overall level seems to be what it should be, it crunches up just a bit if I drive it, and all the controls do what they should.

Here's what's not working:


I plan on double-checking and reflowing solder joints, but if there's anything specific I should be looking about, I'd love to know. Also, I'd still like to know whether I should remove Q6 and install that spacer, or whether I'm OK with it installed as is.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on June 11, 2018, 07:15:11 AM
We can send you a new matched set if you like. Send us an email.

Mike

hello Mike!!

Thanks for the Match pair of transistor!!!!

It solved my noise problem on the FET 500 REV A.

But I still got a problem. The gain reduction does not happen...

Everything's fine when calibrating until I have to put GR ON... nothing's happen on the meter board. The green LED (zero in the meter) stays....

I sent audio sample ont the unit and listened.... No compression...

If you have an Idea...

Thanks again Mike!!!!
Have a good day!!!!

Antoine
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on June 11, 2018, 01:37:24 PM
Hi Mike,

I will definitely do that. Before I do, I want to give a report about where I am with my build just to make sure there's nothing else I might need.

First, the good news: for the most part, the compressor seems to basically be working. I haven't calibrated it yet, but I sent a drum recording through as a test, and it sounds great. The overall level seems to be what it should be, it crunches up just a bit if I drive it, and all the controls do what they should.

Here's what's not working:

  • The 20:1 ratio does not work. In that position, no gain reduction is happening. All other ratios are working as expected.
  • The meter isn't working correctly. The slam LED always stays on, and the only LED that does seem to work correctly is the peak indicator. I've seen some other posts in this thread on this topic and I plan to reexamine my solder joints in these areas.
  • Neither the GR Off or Bypass LEDs illuminate, and the bypass function isn't working. The GR Off function, however, is working.

I plan on double-checking and reflowing solder joints, but if there's anything specific I should be looking about, I'd love to know. Also, I'd still like to know whether I should remove Q6 and install that spacer, or whether I'm OK with it installed as is.

You have to calibrate it.  I'm surprised it's working at all.

Make sure your LED's for bypass and GR off are in the correct polarity.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on June 11, 2018, 01:38:38 PM
hello Mike!!

Thanks for the Match pair of transistor!!!!

It solved my noise problem on the FET 500 REV A.

But I still got a problem. The gain reduction does not happen...

Everything's fine when calibrating until I have to put GR ON... nothing's happen on the meter board. The green LED (zero in the meter) stays....

I sent audio sample ont the unit and listened.... No compression...

If you have an Idea...

Thanks again Mike!!!!
Have a good day!!!!

Antoine

Most likely an issue in your sidechain (back corner of the board), or if you have an A you don't have the R-OPT link in place.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on June 11, 2018, 03:46:27 PM
Most likely an issue in your sidechain (back corner of the board), or if you have an A you don't have the R-OPT link in place.

Mike

Hello,

I've re-checked R-opt link so I'm sure about It.

What do you mean about the back corner of the board?!!!

Thanks a lot!!!!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on June 14, 2018, 12:05:31 PM
Hello,

I've re-checked R-opt link so I'm sure about It.

What do you mean about the back corner of the board?!!!

Thanks a lot!!!!

The part of the board where you have the vertical resistors.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: antoine00 on June 15, 2018, 04:23:55 AM
The part of the board where you have the vertical resistors.

Thanks!!!! I'll take a look!!!!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mcrowe on June 17, 2018, 03:58:21 PM
I'm still having trouble with the 20:1 setting and the metering on my rev A. I was able to calibrate the Q bias and the gain trim on the meter board. However, I couldn't get any of the green LEDs to come on. I wasn't able to perform the GR tracking calibration because the 20:1 ratio isn't doing any gain reduction. All other settings work, but not that one. I've reflowed the solder joints on the switch and the resistor network associated with it, but no luck. In 20:1 mode I do still get makeup gain. The other odd thing is that the slam LED stays lit all the time.

On a possibly related note, I made a mistake when initially populating the LEDs and ended up having to move some around. I couldn't get a reading on two of the yellow ones with my DMM's diode testing function after removing them from the board, so I'm guessing I fried them. At the moment those two aren't installed.

Any ideas where to focus my efforts?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mcrowe on June 26, 2018, 09:25:36 PM
Is Hairball in the house? I'd very much appreciate any input on this.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on June 27, 2018, 12:01:49 AM
Is Hairball in the house? I'd very much appreciate any input on this.

I'm a little bit on vacation for a bit.

You have those green LEDs installed in the correct orientation?  Are you saying you can't get an GR drop on your output?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mcrowe on July 01, 2018, 10:09:52 PM
I’m confident about the LED orientations. I do get gain reduction, just not on the 20:1 setting. The others work. I haven’t had the chance to mess with it in a while but I was going to hunt for shorts in the switch connection area.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on July 02, 2018, 11:46:20 AM
I’m confident about the LED orientations. I do get gain reduction, just not on the 20:1 setting. The others work. I haven’t had the chance to mess with it in a while but I was going to hunt for shorts in the switch connection area.

Weird that the others would work, but not 20:1 since 20:1 is at the start of the ladder.

I would definitely re-flow the ratio switch points. Also check the resistor values across that section.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mcrowe on July 04, 2018, 10:30:39 AM
I tried reflowing those points already without luck. I'll continue to try to troubleshoot in that area. I also found this flaw weird, especially considering that the slam mode works.

Does the fact that the slam LED stays on all the time on the meter board raise any red flags?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on July 09, 2018, 05:12:02 PM
I tried reflowing those points already without luck. I'll continue to try to troubleshoot in that area. I also found this flaw weird, especially considering that the slam mode works.

Does the fact that the slam LED stays on all the time on the meter board raise any red flags?

Does the GR meter work?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: WillDuc on July 25, 2018, 11:19:46 PM
Hi community,

I'm having troubles with the VU meter on my build. Q bias adjustment and peak led adjustment went smoothly.  i see absolutely nothing on the VU meter though (bottom leds) . Solder joints on those leds look pretty good. I will double check resistance values but i doubt it's the cause as i have been pretty meticulous. I don't know where to check at all. Could it be the trim pots on the main PCB ? they were all midway.

Also, i cant get the ratio stepped switch (grayswitch) the turn at all. Did i miss something regarding those stop pins or what?

Any help appreciated.

William
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on July 26, 2018, 12:36:45 PM
Hi community,

I'm having troubles with the VU meter on my build. Q bias adjustment and peak led adjustment went smoothly.  i see absolutely nothing on the VU meter though (bottom leds) . Solder joints on those leds look pretty good. I will double check resistance values but i doubt it's the cause as i have been pretty meticulous. I don't know where to check at all. Could it be the trim pots on the main PCB ? they were all midway.

Also, i cant get the ratio stepped switch (grayswitch) the turn at all. Did i miss something regarding those stop pins or what?

Any help appreciated.

William

Hi,

Emailed you about the switch.

For the VU meter check all of your soldering on everything...look close and re-flow.  Check that the diodes, IC, and caps are inserted correctly.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: eMIX305 on August 07, 2018, 06:06:30 PM
Hey Mike,

    I’m pretty much done with my FET/500 rev D build. I’m in the calibration phase. I’ve gotten thru Q bias & output meter calibration with small corrections. I’ve hit a wall with the gain reduction meter. No leds are registering. I made sure to take the unit out of GR off mode, but nothing changes. Any insight would be amazing.
Thank you,
e
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on August 07, 2018, 06:21:15 PM
Hey Mike,

    I’m pretty much done with my FET/500 rev D build. I’m in the calibration phase. I’ve gotten thru Q bias & output meter calibration with small corrections. I’ve hit a wall with the gain reduction meter. No leds are registering. I made sure to take the unit out of GR off mode, but nothing changes. Any insight would be amazing.
Thank you,
e

To start, make sure your tracking and zero adjust trimmers are dead center.  The are 20 turn pots. Rotate in one direction until you hear a "click", then rotate back 10 turns.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: eMIX305 on August 08, 2018, 05:55:13 PM
Ok...I turned counter clockwise til I heard a click. Then turn ten times clock wise. Nothing yet, so far. What’s the next step?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on August 08, 2018, 05:59:25 PM
Ok...I turned counter clockwise til I heard a click. Then turn ten times clock wise. Nothing yet, so far. What’s the next step?

Both the zero adjust and tracking pots....then try and re-calbrate.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: eMIX305 on August 11, 2018, 12:09:15 PM

So, will re adjusting the tracking pots disturb the output meter calibration I’ve already set? Or is this what I’m trying to do because I’ve calibrated output at a level that the GR meter isn’t reading?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: eMIX305 on August 12, 2018, 01:13:09 AM
I centered all tracking pots, recalibrated q bias, peak led @ 4.88 v & vu -6  @ .388 v. Everything went smooth.
Still no response on GR meter. I will quadruple check the led solder points, but everything looks good. I did notice that when I was calibrating the output via, I didn’t have to adjust the second turn pot, and even when I did turn it, there was no affect on the led read out at all. Not sure if this is a clue to the problem. Let me know if there is anything I can specifically do to narrow it down. Thanks.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on August 14, 2018, 02:09:02 PM
I centered all tracking pots, recalibrated q bias, peak led @ 4.88 v & vu -6  @ .388 v. Everything went smooth.
Still no response on GR meter. I will quadruple check the led solder points, but everything looks good. I did notice that when I was calibrating the output via, I didn’t have to adjust the second turn pot, and even when I did turn it, there was no affect on the led read out at all. Not sure if this is a clue to the problem. Let me know if there is anything I can specifically do to narrow it down. Thanks.

Sorry could you clarify a little more?  Not sure what the second pot is.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: eMIX305 on August 14, 2018, 08:09:52 PM
The second pot I’m referring to is the second turn pot that referenced in the vu calibration sequence. The one used to make sure the vu is reading at -10 (second led on the output meter).
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on August 15, 2018, 01:58:04 PM
The second pot I’m referring to is the second turn pot that referenced in the vu calibration sequence. The one used to make sure the vu is reading at -10 (second led on the output meter).

Are you still not seeing any illuminated LEDs in the GR Meter in either bypass or compression enabled?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: eMIX305 on August 16, 2018, 01:30:28 PM
Correct. At this point, there is still no led response on the GR meter in either mode.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: WillDuc on August 17, 2018, 07:39:24 PM
Hi Mike, I just thought i would report back concerning my problem with the VU meter. After inspection of both boards i found out i had swapped one of the two voltage regulator (lm317LZ) for the 2n5088 transistor. Unsoldering both of them was one hell of a job but it's working fine now!

Thanks for your time,
William
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on August 20, 2018, 01:32:43 PM
Correct. At this point, there is still no led response on the GR meter in either mode.

You'll want to triple check all of the components on the board, look for bad joints and check the parts around the IC on the main PCB.  Make sure values are not swapped.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on August 20, 2018, 01:33:42 PM
Hi Mike, I just thought i would report back concerning my problem with the VU meter. After inspection of both boards i found out i had swapped one of the two voltage regulator (lm317LZ) for the 2n5088 transistor. Unsoldering both of them was one hell of a job but it's working fine now!

Thanks for your time,
William

Nice!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 10, 2018, 11:15:14 AM
Moved from Rev D Rack thread:

Hello all, I completed the build of the 500 series FET/D, but when powered on the gain reduction LEDs are pulsing (with pulse rate controlled by the release potentiometer) and when passing audio through the device, the audio clicks at the rate of the LED pulsing. Last night I was able to investigate with a tech and we discovered that the negative supply pulses when the gain reduction knob is out. When pushed in, we do not see pulsing [which is the reverse of #4 of the FAQ for common issues with this device]. We are not sure why this may be happening and are wondering if anyone may have any advice on the issue?
Many thanks in advance

Are all of the DIP 8 chips installed the the correct place and oriented correctly?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: warmtape on October 11, 2018, 08:04:40 AM
Moved from Rev D Rack thread:

Are all of the DIP 8 chips installed the the correct place and oriented correctly?

Yes, confirmed that they are all placed correctly (attaching a PDF of 4 images of front/back of both PCBs).
This was my first build, so it's messy and I'm wondering if flux residue could cause this type of issue?
However, we are seeing a small pulsing on diode 4, which seems to correspond to the rate of the LED/GR pulsing.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 12, 2018, 01:55:27 PM
Yes, confirmed that they are all placed correctly (attaching a PDF of 4 images of front/back of both PCBs).
This was my first build, so it's messy and I'm wondering if flux residue could cause this type of issue?
However, we are seeing a small pulsing on diode 4, which seems to correspond to the rate of the LED/GR pulsing.

Diode 4 on the main PCB?

Are you sure those Q's on the meter PCB are in the right spot.  There are 2 regulators (LM317) and one transistor (5088).

You should clean off flux, but I doubt that is causing your power issue.

Repair if interested:
https://www.hairballaudio.com/build-support-services

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: ubermetal on October 15, 2018, 03:52:39 PM
Greetings,

A few months ago I built a Rev A. It came together and calibrated easily. I've used it on vocals constantly since I got it, and now I'm addicted to it and don't want to record without it. This past weekend, after perhaps 40 hours of use over the space of several months, a little distortion started creeping in. This was okay at first, as it worked with the style of vocal I was recording. But it kept getting worse, and now the level of distortion makes my Rev A unusable.  It's not present when the unit is bypassed. Where should I start looking?

Thanks in advance!

Josh
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 16, 2018, 01:46:02 PM
Greetings,

A few months ago I built a Rev A. It came together and calibrated easily. I've used it on vocals constantly since I got it, and now I'm addicted to it and don't want to record without it. This past weekend, after perhaps 40 hours of use over the space of several months, a little distortion started creeping in. This was okay at first, as it worked with the style of vocal I was recording. But it kept getting worse, and now the level of distortion makes my Rev A unusable.  It's not present when the unit is bypassed. Where should I start looking?

Thanks in advance!

Josh

Hmmmm weird one.  Hard to say without probing around which is near impossible without a jig.  Does Q6 have a heatsink on it? Are any resistors around Q6 burning?

Could start by trying a new Q6.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: ubermetal on October 16, 2018, 05:02:21 PM
Q6 does have a heat sink on it. The unit does seem to be running hot, though. I'll feel around for hot parts and probably replace Q6.

Thanks Mike!

Hmmmm weird one.  Hard to say without probing around which is near impossible without a jig.  Does Q6 have a heatsink on it? Are any resistors around Q6 burning?

Could start by trying a new Q6.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 16, 2018, 09:52:54 PM
Q6 does have a heat sink on it. The unit does seem to be running hot, though. I'll feel around for hot parts and probably replace Q6.

Thanks Mike!

Q6 should get hot...but over time it can get too hot.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: ubermetal on October 17, 2018, 10:17:15 AM
Hence the heat sink. Got it. Do you think it would help to put a fan on it?

Q6 should get hot...but over time it can get too hot.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 17, 2018, 12:49:20 PM
Hence the heat sink. Got it. Do you think it would help to put a fan on it?

No it shouldn't fail with the supplied sink.  More likely a bad part.  If it's even Q6.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: warmtape on October 22, 2018, 05:55:22 AM
Diode 4 on the main PCB?

Are you sure those Q's on the meter PCB are in the right spot.  There are 2 regulators (LM317) and one transistor (5088).

You should clean off flux, but I doubt that is causing your power issue.

Repair if interested:
https://www.hairballaudio.com/build-support-services

Mike

Hi Mike, yes, I saw pulsing on diode 4 of the main pcb. I've also triple checked that the Qs on the meter PCB and that the 2 regulators and one transistor are correctly placed.
I will try to probe the board again but please let me know if pulsing on diode 4 is strange and if you have any idea about that.
Thanks
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 22, 2018, 02:00:05 PM
Hi Mike, yes, I saw pulsing on diode 4 of the main pcb. I've also triple checked that the Qs on the meter PCB and that the 2 regulators and one transistor are correctly placed.
I will try to probe the board again but please let me know if pulsing on diode 4 is strange and if you have any idea about that.
Thanks

Super weird.

D4 is just a protection diode for the main rail.  It should not be pulsing AC or DC.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: ubermetal on October 25, 2018, 06:09:40 PM
It was Q6! I replaced it, and it's running perfectly again. Thanks a million, Mike!

No it shouldn't fail with the supplied sink.  More likely a bad part.  If it's even Q6.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on October 26, 2018, 03:32:53 PM
It was Q6! I replaced it, and it's running perfectly again. Thanks a million, Mike!

Nice.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: warmtape on October 29, 2018, 02:24:01 PM
Super weird.

D4 is just a protection diode for the main rail.  It should not be pulsing AC or DC.

Another very strange aspect is that if, while the unit is turned on, I apply pressure with my finger to the meter board directly on top of the 1/8" jack from the top of the board (so the pressure is being applied not to the jack itself but to the underside of the jack where it's soldered (since the 1/8" jack is soldered from above as opposed to the rest of the components on the board)) then the audio does not pulse but seems to go through smoothly. Once I stop applying pressure there the pulsing starts again. The soldering there seems fine. I noticed this entirely by accident, but does this happen to shed any light on what might be happening?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 02, 2018, 12:26:39 AM
Another very strange aspect is that if, while the unit is turned on, I apply pressure with my finger to the meter board directly on top of the 1/8" jack from the top of the board (so the pressure is being applied not to the jack itself but to the underside of the jack where it's soldered (since the 1/8" jack is soldered from above as opposed to the rest of the components on the board)) then the audio does not pulse but seems to go through smoothly. Once I stop applying pressure there the pulsing starts again. The soldering there seems fine. I noticed this entirely by accident, but does this happen to shed any light on what might be happening?

You're probably just grounding the noise.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: emmanuel_szczygiel on November 10, 2018, 11:43:56 AM
Hi Mike,

I just finished my FET/500 Rev D but i made some mistakes during the building which prevents it to works well. I reversed R540 and R086 and on the meter board i reversed VR1 and VR2  :-\

After putting them back in the right place here are the symptoms when I send a 1kHz sin wave (0.775 VAC) : I hear the signal BUT the volume is low with some noise. When INPUT knob and OUTPUT knob are fully clockwise I measure about 0.65 VAC at the output of the compressor. Furthermore when I turn Q Bias nothing happens.

Can you tell me which components I probably damaged by inverting the trimmers?

Thank you in advance for your precious help

Manu
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 14, 2018, 03:18:39 PM
Hi Mike,

I just finished my FET/500 Rev D but i made some mistakes during the building which prevents it to works well. I reversed R540 and R086 and on the meter board i reversed VR1 and VR2  :-\

After putting them back in the right place here are the symptoms when I send a 1kHz sin wave (0.775 VAC) : I hear the signal BUT the volume is low with some noise. When INPUT knob and OUTPUT knob are fully clockwise I measure about 0.65 VAC at the output of the compressor. Furthermore when I turn Q Bias nothing happens.

Can you tell me which components I probably damaged by inverting the trimmers?

Thank you in advance for your precious help

Manu

It's highly unlikely anything is damaged unless you damaged a pad or trace removing them.  It sounds more like your gain amp stage just isn't working. Or possibly your qbias.  Do you have away to probe the circuit while it powered? Like an extender jig, or chassis big enough that you can remove the slots on the right and get in with a probe?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: emmanuel_szczygiel on November 17, 2018, 11:51:42 AM
It's highly unlikely anything is damaged unless you damaged a pad or trace removing them.  It sounds more like your gain amp stage just isn't working. Or possibly your qbias.  Do you have away to probe the circuit while it powered? Like an extender jig, or chassis big enough that you can remove the slots on the right and get in with a probe?

Thanks for your answser Mike.
Yes I can probe the circuit while it powered. Are there any tests points to identify where the problem comes from?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on November 17, 2018, 11:56:55 AM
Thanks for your answser Mike.
Yes I can probe the circuit while it powered. Are there any tests points to identify where the problem comes from?

For all measurements, use the positive terminal of D4 for your GND reference.

1. Measure your Q1 DC V at the gate...what is the most negative you can get it?
2. Measure your AC V with a 1KHz 0dB signal at C7 (either pad) and output transformer brown lead. Control set mid way, GR off.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on December 10, 2018, 01:16:21 PM
Hi Mike!

I built 2 units of 500/Rev D. So far so good... It's working properly, but for 2 things.

1st is the VU meter... I can't get to set -10 on the calibration process... The VR2 almost does nothing to the VU behavior...

Likely something on the meter PCB.  Swap the two meter PCBs and see if the issue follows the meter PCB. If so you'll need to go through and check every component for value and orientation and re-dlow and suspect solder joints.

The other thing is about the stereo link... when I plug the p2 cable in both units, one of the units reacts really weird. GR meter gets pinned to -9 varying a lil bit and it acts very weird, not properly. Any ideas?

Also, I kind of didn't understand how it works... It sums both sidechains? Or it's about the settings I do at one of the units that controls the other one?
Sorry for the newbie question... But it'd help me a lot to clarify this!

I'll come back with pics of the st link issue and maybe upload a video of the calibration thing...

Thanks very much!

I wouldn't worry about it until you can get the one unit properly calibrated.  This issue is probably caused by the first issue.  We're the FET'S in both units matched with each other?

Yes they are summed...your release will be doubled so you can set one to super fast and the other as needed. Set the rest of the controls the same and then trim them to match GR and output level...they'll be a little off because of tolerance.

Thanks,

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: guismarquesrj on December 10, 2018, 06:23:56 PM
Likely something on the meter PCB.  Swap the two meter PCBs and see if the issue follows the meter PCB. If so you'll need to go through and check every component for value and orientation and re-dlow and suspect solder joints.

I wouldn't worry about it until you can get the one unit properly calibrated.  This issue is probably caused by the first issue.  We're the FET'S in both units matched with each other?

Yes they are summed...your release will be doubled so you can set one to super fast and the other as needed. Set the rest of the controls the same and then trim them to match GR and output level...they'll be a little off because of tolerance.

Thanks,

Mike

Gonna test it tonight (here in Brazil!) and get back to you asap...

About the matched transistor, I think yes, as I bought 2 units together and I remember it was labeled "matched" or something like that....

but just to be sure, what transistor are u talking about? the (Q200) 2n5088 on the meter board?

Thanks VERY MUCH for the support, Mike :)
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on December 12, 2018, 01:41:09 PM
Gonna test it tonight (here in Brazil!) and get back to you asap...

About the matched transistor, I think yes, as I bought 2 units together and I remember it was labeled "matched" or something like that....

but just to be sure, what transistor are u talking about? the (Q200) 2n5088 on the meter board?

Thanks VERY MUCH for the support, Mike :)

I was talking about the 2N5457's Q1/Q11 on both units should be 4 way matched.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: emmanuel_szczygiel on December 12, 2018, 04:58:05 PM
Hi Mike,

While it's powered, here are my results :
Between D4 and Q1(gate) : -1.33DCV (this value doesn't change)

With 1kHz signal, control set mid way, GR off :
Between D4 and C7 : 0.014ACV
Between D4 and brown lead : 0.31ACV

Thanks,
Manu

For all measurements, use the positive terminal of D4 for your GND reference.

1. Measure your Q1 DC V at the gate...what is the most negative you can get it?
2. Measure your AC V with a 1KHz 0dB signal at C7 (either pad) and output transformer brown lead. Control set mid way, GR off.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on December 15, 2018, 11:54:14 AM
Hi Mike,

While it's powered, here are my results :
Between D4 and Q1(gate) : -1.33DCV (this value doesn't change)

With 1kHz signal, control set mid way, GR off :
Between D4 and C7 : 0.014ACV
Between D4 and brown lead : 0.31ACV

Thanks,
Manu

Carefully remove Q1, set it aside.

Do you pass signal now?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: emmanuel_szczygiel on December 23, 2018, 02:06:32 PM
Hi Mike!
Good news, I finally discovered that one of my audio cables that I used for calibration was damaged!
So, I started the calibration again, (the amplification seems ok) BUT other problems appeared...
- Q-bias does not react when I turn it (as much on the output voltage as on the leds).
- The led220 "SLAM" is constantly on, even when the bypass is engaged.
- Led211 to led219 reacted in a strange way during the beginning of calibration.

My hypothesis comes from the TL071 which controls this series of LEDs (211-220). Indeed, I had indicated that I had reversed R540 and R86, after that Q11 was replaced because it was damaged. The sensitive TL071 could also be affected by the inversion of the trimmers. What do you think?

Let me know
Many thanks (and Merry Christmas!)
Manu

Carefully remove Q1, set it aside.

Do you pass signal now?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mcrowe on January 06, 2019, 02:47:05 PM
I've managed to clear up most of the issues I've had with my FET/500 build, but the GR meter is still flummoxing me. The slam LED stays lit all the time, and the -22 LED also stays very faintly lit all the time. The meter doesn't seem to react to program material. When I apply power, the GR meter goes up and down through its full range a couple of times very quickly, so the LEDs are working, at least. I've checked for continuity in the areas around IC204 as well as around IC1 on the main board, and everything seems OK. Can you offer any advice?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 07, 2019, 01:24:44 PM
I've managed to clear up most of the issues I've had with my FET/500 build, but the GR meter is still flummoxing me. The slam LED stays lit all the time, and the -22 LED also stays very faintly lit all the time. The meter doesn't seem to react to program material. When I apply power, the GR meter goes up and down through its full range a couple of times very quickly, so the LEDs are working, at least. I've checked for continuity in the areas around IC204 as well as around IC1 on the main board, and everything seems OK. Can you offer any advice?

Make sure the IC on the main board is correct. It should be a 071 not 072.  We had a few kits ship with 072's.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: mcrowe on January 07, 2019, 09:33:42 PM
The IC is an 071. I just put the meter on it and I'm showing 15VDC on the pin carrying the VU signal and about 13VDC on the pin carrying the GR signal. Is that expected?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: emmanuel_szczygiel on January 08, 2019, 12:36:43 PM
Hello Mike,
Did you see my last message? (Below here)
Thanks

Hi Mike!
Good news, I finally discovered that one of my audio cables that I used for calibration was damaged!
So, I started the calibration again, (the amplification seems ok) BUT other problems appeared...
- Q-bias does not react when I turn it (as much on the output voltage as on the leds).
- The led220 "SLAM" is constantly on, even when the bypass is engaged.
- Led211 to led219 reacted in a strange way during the beginning of calibration.

My hypothesis comes from the TL071 which controls this series of LEDs (211-220). Indeed, I had indicated that I had reversed R540 and R86, after that Q11 was replaced because it was damaged. The sensitive TL071 could also be affected by the inversion of the trimmers. What do you think?

Let me know
Many thanks (and Merry Christmas!)
Manu
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 08, 2019, 02:48:17 PM
Hello Mike,
Did you see my last message? (Below here)
Thanks

I doubt you damaged the IC from the trimmers.  Maybe it's just bad from heat or static.  I would check every joint and trace.  If you're swapping our parts it's really easy to lose a pad.

Everything else works?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: adam.schw on January 11, 2019, 07:16:20 PM
Need some help on calibration...

I'm doing a rev A.

On the gain trim calibration, at 4.88V even when I have the trimpot fully rotated CC, the peak light doesn't light up. when I rotate the output to 7.2V it lights up.

on the next step with VU trim, at .388v the -10 led does not light, but when i adjust the output to .65v with the trimpot fully rotated CC the -10 led lights up.

Curiously, when I bypass the unit, my sine wave output appears to be reduced to half the voltage....any ideas for what I messed up?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: adam.schw on January 11, 2019, 09:23:11 PM
Need some help on calibration...

I'm doing a rev A.

On the gain trim calibration, at 4.88V even when I have the trimpot fully rotated CC, the peak light doesn't light up. when I rotate the output to 7.2V it lights up.

on the next step with VU trim, at .388v the -10 led does not light, but when i adjust the output to .65v with the trimpot fully rotated CC the -10 led lights up.

Curiously, when I bypass the unit, my sine wave output appears to be reduced to half the voltage....any ideas for what I messed up?

Update/Side note, SLAM led is constantly lit. I threw it on a vocal track and I can the compression and whatnot, so maybe it's just an issue with the metering board? Still doesn't explain the output measuring half voltage with the module bypassed though.  I checked in my DAW as well, and whatever gets ran through it bypassed is definitely a lower output.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: cah9858 on January 11, 2019, 10:01:12 PM
I am having the same issue as warmtape on my rev F, weird pulsing. Was there a fix for this?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: emmanuel_szczygiel on January 12, 2019, 10:17:14 AM
Hi Mike,
I finally achieve to calibrate my FET/500. By turning it, the q bias has finally reacted and I was able to go through the process.
Works great and sound great!
Thanks for your help,
Manu

I doubt you damaged the IC from the trimmers.  Maybe it's just bad from heat or static.  I would check every joint and trace.  If you're swapping our parts it's really easy to lose a pad.

Everything else works?

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 13, 2019, 12:28:03 PM
I am having the same issue as warmtape on my rev F, weird pulsing. Was there a fix for this?

What's happening exactly?

I think we fixed that one, if it's the one I'm thinking about the 100Ω and 100KΩ trimmers on the main PCB were swapped.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 13, 2019, 12:29:29 PM
Hi Mike,
I finally achieve to calibrate my FET/500. By turning it, the q bias has finally reacted and I was able to go through the process.
Works great and sound great!
Thanks for your help,
Manu

Nice!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 13, 2019, 12:32:51 PM
Update/Side note, SLAM led is constantly lit. I threw it on a vocal track and I can the compression and whatnot, so maybe it's just an issue with the metering board? Still doesn't explain the output measuring half voltage with the module bypassed though.  I checked in my DAW as well, and whatever gets ran through it bypassed is definitely a lower output.

So with say a 0.775 VAC input in bypass mode you get 0.375 VAC ish on the output?

Probably on of the relays isn't working so you're getting an unbalanced signal. Check all of those solder joints.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 13, 2019, 12:37:02 PM
Need some help on calibration...

I'm doing a rev A.

On the gain trim calibration, at 4.88V even when I have the trimpot fully rotated CC, the peak light doesn't light up. when I rotate the output to 7.2V it lights up.

on the next step with VU trim, at .388v the -10 led does not light, but when i adjust the output to .65v with the trimpot fully rotated CC the -10 led lights up.

Curiously, when I bypass the unit, my sine wave output appears to be reduced to half the voltage....any ideas for what I messed up?

Not sure what you mean on the first two.  Not enough info for me to diagnose (where the GR ON/OFF and so on).
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: cah9858 on January 13, 2019, 08:47:42 PM
What's happening exactly?

I think we fixed that one, if it's the one I'm thinking about the 100Ω and 100KΩ trimmers on the main PCB were swapped.

Mike

That was totally it. Calibrated, tested and is working/sounding great. Thanks!
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: adam.schw on January 13, 2019, 11:22:52 PM
Not sure what you mean on the first two.  Not enough info for me to diagnose (where the GR ON/OFF and so on).

Ok, first off for the half output on bypass thing...apparently I wasn't paying attention when I grabbed a cable, because I had a TS instead of TRS. So i've got that sorted out now.

As far as the other stuff...

Going through the calibration steps, 20:1, GR off, trying to do gain trim calibration, at 4.88VAC, the peak light does not come on, regardless of the position of the gain trimpot. Once I increase output to about 7.2VAC, I can get the peak light to come on.

In regards to VU trim, at .388VAC, the -10db LED will not come on regardless of the position of the trimpot. At about .7VAC, I can adjust the trimpot to bounce between the -10db and -20db LED.

Also, the SLAM LED is always on when unit bypass button is activated. I've checked (nearly anyway) all off my solder joints on both boards and re-flowed any that I thought might be suspect.

I have checked with actual audio, however, and can confirm that the unit is actually compressing. I know my calibration is a bit off (obviously). I'm not sure how the SLAM LED is supposed to work, but when the unit is "not doing" any GR the slam LED is lit up, but as audio hits the treshold, the GR meter seems to be working. It's confusing to explain, and could email a video if necessary.

Edit/update:
I dicked around with the 0 adjust, and got the slam light to come off and sit at 0 while there's no GR - so that's cool.
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 14, 2019, 01:23:42 PM
Going through the calibration steps, 20:1, GR off, trying to do gain trim calibration, at 4.88VAC, the peak light does not come on, regardless of the position of the gain trimpot. Once I increase output to about 7.2VAC, I can get the peak light to come on.

That's a fairly simple/small circuit built around the 2N5088. It's posted below. You need to triple check all of those component values and solder points.

In regards to VU trim, at .388VAC, the -10db LED will not come on regardless of the position of the trimpot. At about .7VAC, I can adjust the trimpot to bounce between the -10db and -20db LED.

Also, the SLAM LED is always on when unit bypass button is activated. I've checked (nearly anyway) all off my solder joints on both boards and re-flowed any that I thought might be suspect.

I have checked with actual audio, however, and can confirm that the unit is actually compressing. I know my calibration is a bit off (obviously). I'm not sure how the SLAM LED is supposed to work, but when the unit is "not doing" any GR the slam LED is lit up, but as audio hits the treshold, the GR meter seems to be working. It's confusing to explain, and could email a video if necessary.

Edit/update:
I dicked around with the 0 adjust, and got the slam light to come off and sit at 0 while there's no GR - so that's cool.

The GR meter works like the traditional meter. Having the SLAM light lit, just means the meter is drifting right of zero.I would center both the zero adj and GR tracking trimmer before that calibration step.  They are 20 turn trimers, turn one direction until you here a quiet click then turn back the other direction 10 turns.

Mike
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: Hairball Audio on January 14, 2019, 01:24:20 PM
here is that peak circuit
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: adam.schw on January 15, 2019, 01:35:45 AM
That's a fairly simple/small circuit built around the 2N5088. It's posted below. You need to triple check all of those component values and solder points.

The GR meter works like the traditional meter. Having the SLAM light lit, just means the meter is drifting right of zero.I would center both the zero adj and GR tracking trimmer before that calibration step.  They are 20 turn trimers, turn one direction until you here a quiet click then turn back the other direction 10 turns.

Mike

I went through and verified all the values on the meter board, everything seems to be correct. Went over all the joints that seemed could be possibly suspect, no avail. Is it possible I fried something to cause this? Maybe a problem somewhere on the main board? or would this for sure be a metering board thing?
Title: Re: [BUILD] FET/500 Official Support Thread
Post by: adam.schw on January 22, 2019, 04:24:16 PM
I went through and verified all the values on the meter board, everything seems to be correct. Went over all the joints that seemed could be possibly suspect, no avail. Is it possible I fried something to cause this? Maybe a problem somewhere on the main board? or would this for sure be a metering board thing?



I've continued to attempt to troubleshoot with no avail. No matter what it seems the output meter is not lighting up correctly with what is going on with the actual output despite what the trim is set to.

At some point in the coming months I intend to build another one of these. Would it be possible to purchase a meter board? That way, if the problem still exists, we can at least narrow it down to the main PCB as the problem, and then i'd already have a meter board ready to go for my next build. Is there potentially a dead component or damaged component somewhere causing this? Any better ideas?