Hairball Audio

Re: [BUILD] FET/500 Official Support Thread
« Reply #440 on: July 15, 2019, 04:24:30 PM »
well, since it drops audio significantly it doesnt make much sense i guess - if i apply 1k sine @ .775V (measured in BYP at the output), it drops to NOTHING even with the QBias fully CCW and input and output centered, and .110V with input and output fully CW.

Under the standard test set-up:
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 -)

What is your ACV @ all 3 pins of the output pot?  YOU MUST USE THE + LEAD OF D4 AS YOU COMMON PROBE GROUND POINT.
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Re: [BUILD] FET/500 Official Support Thread
« Reply #441 on: July 15, 2019, 05:37:58 PM »
Under the standard test set-up:
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 -)

What is your ACV @ all 3 pins of the output pot?  YOU MUST USE THE + LEAD OF D4 AS YOU COMMON PROBE GROUND POINT.

ground pin - 0V
middle - 0,02V
bottom - 0,12V
those with the QBias centered
(still the lunchbox output shows 0,775V between pins 2+3 with the unit in BYP mode, just to make sure i am not making a fool of myself here ;))
thanks a lot!!

Hairball Audio

Re: [BUILD] FET/500 Official Support Thread
« Reply #442 on: July 15, 2019, 06:21:18 PM »
Something is definitely messed up around Q2/3.  Make absolutely sure all of the components in that signal amp stage are in the right place and properly soldered with no lifted pads.

If all else fails we can send you a new Q2/3,  Maybe one died.

Mike
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Re: [BUILD] FET/500 Official Support Thread
« Reply #443 on: July 24, 2019, 08:18:00 PM »
I have a 1176 Fet Rev a 2018 model.  I built this a year ago and it works great.  When I finished it it did not work.  There was one cold solder joint which I fixed in 5 minutes. 

I just moved the 1176 rev a to a different rack and the output went out again.  The input works in GR mode when I hit +4 or +8 there is no movement on the vu meter.  So, I take it the output circuit is not working.  When should I look for when trouble shooting this problem?

Re: [BUILD] FET/500 Official Support Thread
« Reply #444 on: July 25, 2019, 12:01:22 PM »
I have preformed the tests on this page

https://www.hairballaudio.com/blog/resources/post/fetrack-troubleshooting-guide

From the start every tests passed until I got to

2.  Amplification Stages

Output Transformer BRN

The BRN one failed.  The TP 1, 15, 17 passed though.

Test 3 GR In All pass

Test 4 GR out All pass

Test 5 GR Th V All pass


So does that narrow the problem down a bit to what it could be?



So, the only fail was

Output Transformer BRN

Notes on that:

Low voltage at Output Transformer BRN: have issues in your Signal Line Amp section marked on the PCB. Check the DC voltage chart for this section.
Low voltage at Output XLR + and -: likely have issues with output transformer wiring.

What DC voltage should I check for this and how do I do it?

EDIT

I have tested Q 4, Q5 and Q6 DC voltage and they are all good.

I think I might have a bad solder joint on blk I will re-solder and get back to you if this fixes the issue.

It was the blk solder joint of the output transformer.  It is working now!!!
« Last Edit: July 25, 2019, 01:18:51 PM by arsmusic »

Hairball Audio

Re: [BUILD] FET/500 Official Support Thread
« Reply #445 on: July 25, 2019, 02:13:43 PM »
I have preformed the tests on this page

https://www.hairballaudio.com/blog/resources/post/fetrack-troubleshooting-guide

From the start every tests passed until I got to

2.  Amplification Stages

Output Transformer BRN

The BRN one failed.  The TP 1, 15, 17 passed though.

Test 3 GR In All pass

Test 4 GR out All pass

Test 5 GR Th V All pass


So does that narrow the problem down a bit to what it could be?



So, the only fail was

Output Transformer BRN

Notes on that:

Low voltage at Output Transformer BRN: have issues in your Signal Line Amp section marked on the PCB. Check the DC voltage chart for this section.
Low voltage at Output XLR + and -: likely have issues with output transformer wiring.

What DC voltage should I check for this and how do I do it?

EDIT

I have tested Q 4, Q5 and Q6 DC voltage and they are all good.

I think I might have a bad solder joint on blk I will re-solder and get back to you if this fixes the issue.

It was the blk solder joint of the output transformer.  It is working now!!!

All fixed?  Sounds like this was a FET/RACK?
Hairball Audio, LLC
DIY Parts and Kits
https://hairballaudio.com

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Re: [BUILD] FET/500 Official Support Thread
« Reply #446 on: July 25, 2019, 07:50:53 PM »
Yes, thanks it is all fixed.  It was a Rev A fet rack.