41

CP5176 FET compressor / Re: No sound CP5176

« Last post by JPK on January 26, 2026, 09:32:16 AM »

That looks very much like your issue.
One of the phase is not connected.
It can also explain the low levels.

42

MU524 Vari-Mu Tube Compressor / Re: Initial AC voltage jump

« Last post by CGMix on January 24, 2026, 11:19:45 PM »

Here is a shot

43

MU524 Vari-Mu Tube Compressor / Re: Initial AC voltage jump

« Last post by CGMix on January 24, 2026, 07:08:51 PM »

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

44

CP5176 FET compressor / Re: No sound CP5176

« Last post by Stam on January 24, 2026, 11:13:15 AM »

Hi again!

Maybe I have found the problem.

When I connect the compressor direct from an electronically balanced micpre XLR output and out from the compressor with an XLR to the soundcard the bass response seems okey. When I connect it through my patchbays backside in normalled mode (which should be balanced) the bass is lacking again. It looks like the problem is in the patchbay.

The compressor is probebly okey now. I’ll get back to you if I suspect that there is a problem that actually has to do with the compressor.

Thank you for your patience and support!
Mats

45

CP5176 FET compressor / Re: No sound CP5176

« Last post by JPK on January 23, 2026, 05:10:16 PM »

I am running short of ideas. 
Do you want to send it to us for a check? Contact me at jpk@soundskulptor.com

46

CP5176 FET compressor / Re: No sound CP5176

« Last post by Stam on January 23, 2026, 10:18:29 AM »

If I have the compressor vertical as it should sit in the 500 rack the input transformer got it´s marking upwards.
The relay got the line downwards. The resistance goes from 0 to 1.785K on TP1 when turning the P1 pot from min to max.

47

CP5176 FET compressor / Re: No sound CP5176

« Last post by JPK on January 23, 2026, 09:47:41 AM »

The values are correct.
Check that the input transformer is inserted the right way around, with the markings facing upwards.
Check that the relay is inserted the right way around, with the white line down.
Check that the resistance between TP1 and ground goes from 0 to 1k6 when turning P1.

48

CP5176 FET compressor / Re: No sound CP5176

« Last post by Stam on January 22, 2026, 08:14:27 PM »

Ok, I see ...


Between edge connector fingers 8 & 10 I get 2.16 Kohm

49

CP5176 FET compressor / Re: No sound CP5176

« Last post by JPK on January 22, 2026, 03:20:25 PM »

I suppose that you mean the fingers on CN3a?
No. I mean the card edge connector at the back of the card with golden fingers (connecting to the lunchbox).

And without any power I suppose?
Correct

50

CP5176 FET compressor / Re: No sound CP5176

« Last post by Stam on January 22, 2026, 02:40:55 PM »

Hi!

Does this voltage vary, from 0 to max) with the P1 rotation?
 Yes. But still just 0.11 VAC at maximum P1 on TP1. On L1 I get from 0 VAC on P1 at minimum and 10.8 VAC when P1 at maximum. (1Khz 1VAC)
 
The resistance between side pins of P1 read 1.69 K when front PCB is attached to main PCB.
 
I´m really confused when it comes to check the input transformer coils resistance …
I suppose that you mean the fingers on CN3a? Shall the front PCB be attached? And without any power I suppose? When I see the main PCB so I can read text “SOUNDSKULPTOR” on It. I got one upper row of 10 solder joints and one row under with 10 solder joints on CN3a. If the upper row is 1-10, and the lower row is 11-20. Between which numbers shall I test the resistance?  
 
I have balanced cable in and out. Checked with another 500 series module on the XT500 extender and it sounds fine.