[BUILD] FET/500 Official Support Thread

[antoine00]

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!!!

 

[milchmannverleih]

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

 

[Echo North]

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

 

[ninopelo29]

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!!

 

[Echo North]

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

 

[ninopelo29]

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!

 

[Echo North]

*****************
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

 

[ninopelo29]

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!

 

[Echo North]

**************

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

 

[theodorblumentopf]

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

 

[Echo North]

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

 

[denov]

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.

 

[Echo North]

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

 

[philwantspro6]

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.

 

[Echo North]

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

 

[mcrowe]

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?

 

[Alsgro]

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!!

 

[mcrowe]

Are they about 1/4" long? I did find one little piece like that in my container of discarded leads.

 

[mcrowe]

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.

 

[Alsgro]

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.