[CGMix]

After sending a 1V, 1K tone of not the compressor, my voltage jumps to a little over 7V instead of 3-4V. This does affect the rest of the calibration. Where should I look? All other voltages look to be where they should. 

[JPK]

Check that you have not reversed transformer T1. The label must be facing the back of the module.
What are the AC levels on TP3 and TP4, relative to 0V (1.75V)?

[CGMix]

JP! Thanks for the reply. At TP3/4 I’m getting 3.9vac. On my other working compressor it sits at 1.8, I believe. I pulled the transformer last night, thinking I may have pierced R1, but I had not. Also, I’ll have to check again, but I think I was measuring about half a volt on each grid of the tube. And then it jumps up to about the 4V pretty quickly thereafter. I believe the Transformers is correct because it’s installed in the same manner as my other

[CGMix]

for reference

[JPK]

Is the label on the transformer facing towards the back of the module?
Check the input transformer coils resistance (in circuit with potentiometer IN on 10):
pin2-pin4 : 37ohms
pin3-pin5 : 37ohms
pin7-pin9 : 98ohms
pin8-pin10: 98ohms
pin7-pin10: 194ohms

[CGMix]

Well damn, that was it. Transformer was upside down…

[JPK]

[CGMix]

I wanted to jump back on this thread real quick and ask about another jump. This same unit will jump up in input after using it for several minutes. The meter will peg right and distort. So when it does this I can turn the input and output all the way down and still faintly hear it. But then last night I used it for a couple of hours and it never had an issue. 🤷🏼 I swapped slots on the rack to double check as well

[CGMix]

Here is a shot

[JPK]

I am not sure I understand well.
Do you have a sudden excess of input gain? Does it looks like a bad contact? How does it ends? Please explain more.

[CGMix]

So in that photo I have a vocal running through and if you look at the knobs, all of them are down. But the signal is still getting slammed. I can faintly hear the source even with the output down. The signal is distorted as well. But again, this is not a constant issue. Sometimes it slams the signal, and sometimes it operates normally.

[JPK]

When this happens, does the needle return to 0 if you remove the signal completely?

[CGMix]

Yes it does. It’s still responding to signal, but it’s almost as if something is driving the input way up

[JPK]

It looks like a sidechain gain issue.
Check the solder joints of R22, R23, R28, D4.

[CGMix]

Ok I hit all of those pads again, but still the same issue. The good news is now the issue is consistent and not intermittent anymore. but I should mention this happened before I re-soldered the pads. The issue is also on my right unit, so when I link both of my units together, it will pull the heavy compression on the left unit as well. 

[JPK]

Check that the input potentiometer is working by measuring the resistance between pins 7 & 10 of the input transformer. The value should vary from 0 to 200 ohms when rotating the input potentiometer.

[CGMix]

Yeah it looks like that may be it. The ohm load doesn’t change. It’s stuck at 100ohms

[JPK]

Check the solder joints of the potentiometer P1, of the connectors J2a and J2b and of the transformer daughterboard to main PCB connector.

[CGMix]

OK I checked all of those connections again and I still have the same results. However, I  have a second unit that I pulled the front panel off of and swapped them around. so taking the front panel with a known issue and putting it on a compressor with no known issues, it still behaves in the same way. So I believe the issue is within the front panel. Have you ever come across a bad potentiometer? I think I may pull it out and measure it.

[JPK]

It’s stuck at 100ohms
Check the input pot directly on its pins, with the front PCB disconnected.
It should go from 0 to 10kohms.

[CGMix]

OK I tested all three pots while I had the front panel pulled, the bottom two were in range and the input potentiometer just showed out of limit. But I believe it might have a break internally. If I wiggle the stem, it will jump in ohms. do you know where I can get another one of these in the US?