[BUILD] FET/500 Official Support Thread

[mnats]

FET/500 page, linked searchable documentation
Calibration video added!
General troubleshooting page
Sub-site for boards and kits

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. Thank you.

 

[mnats]

Reserved

 

[Cgaines]

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?

 

[Echo North]

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. 

 

[Cgaines]

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?

 

[Echo North]

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

 

[Echo North]

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

 

[Cgaines]

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?

 

[Cgaines]

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.

 

[Echo North]

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.

 

[Echo North]

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.

 

[Echo North]

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.

 

[Cgaines]

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 shit.. 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.

 

[ericyoshino]

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

 

[Echo North]

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

 

[ericyoshino]

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!

 

[Dr Gris]

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

 

[ericyoshino]

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!

 

[Echo North]

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.

 

[Echo North]

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.