41

CP554 Diode bridge compressor / Re: Cant get 3v at step 5

« Last post by JPK on April 13, 2026, 03:40:21 PM »

Is it time to send it to our workshop for a check?

42

CP5176 FET compressor / 2nd CP 5176 Failed at TP3 Troubleshooting

« Last post by RFR on April 13, 2026, 12:30:02 PM »

Hi community,

I'm having an issue with my 2nd CP 5173 (#2).
I don't get the voltages at TP2 & TP3 compared to my 1st unit (#1).

Anything from 1:2 to 1:20 doesen't come close measurements.
Also I see a bigger gap on TP1 when I increase Source Voltage. Did I install T1 wrong? I'm sure I checked this 2 times prio soldering.

I can exclude front PCB, as I have the same results when using the front #2 at main #1 pcm.

Any idea why my Voltages are tht so far off?
Measurements:

43

MU524 Vari-Mu Tube Compressor / Re: Low output voltage step 6

« Last post by JPK on April 13, 2026, 11:33:34 AM »

With a 1VAC signal at the input, IN pot on 10, power off, how many millivolts AC do you get on the input transformer between pins 2 and 5?

44

CP554 Diode bridge compressor / Re: Cant get 3v at step 5

« Last post by vwyf11 on April 13, 2026, 04:34:21 AM »

I’ve replaced D20, Q7, U3, TR2.  Before replacing anything I checked between TP2 and TP3 and was getting 0.001V.  After replacing all the components listed, I’m getting the same values. 

Here are the values from the DC voltage checks in the link you gave from before:

A: 1.14V this value bounces around a lot
B: 0.561V
C: 0.525V this value bounces around a lot
D: 28.1V
E: 28.1V
F:0.001V

TP3 to 0V measure -12.8V

45

MU524 Vari-Mu Tube Compressor / Re: Low output voltage step 6

« Last post by Ben on April 11, 2026, 09:23:01 PM »

Apologies, my DMM lead must have had a bad connection testing TP2. I actually have 29.79vdc and 0.145vac @ TP2. TP3 is the same

46

MU524 Vari-Mu Tube Compressor / Re: Low output voltage step 6

« Last post by JPK on April 11, 2026, 06:49:12 PM »

TP2=  0.057 VDC
Here is the issue. You should get around 30VDC.
You must check the solder joints on R7, on the tube socket, on the connector that links the tube PCB to the main PCB.
Check that the 48V gets to both sides of R7 (you can check without the tube inserted).

47

MU524 Vari-Mu Tube Compressor / Re: Low output voltage step 6

« Last post by Ben on April 07, 2026, 04:22:11 PM »

Sure can, 
TP2= 0.297 VAC and 0.057 VDC
TP3= 0.077 VAC and 0 VDC

Pot 1, R1 and R2 test ok as well
Thanks,
Ben

48

MU524 Vari-Mu Tube Compressor / Re: Low output voltage step 6

« Last post by JPK on April 07, 2026, 09:04:14 AM »

Can you please also report the values on TP2 and TP3?

49

MU524 Vari-Mu Tube Compressor / Re: Low output voltage step 6

« Last post by Ben on April 03, 2026, 05:05:53 PM »

I reheated all solder joints and rechecked for bridging or shorts, no change
Thanks,
Ben

50

MU524 Vari-Mu Tube Compressor / Re: Low output voltage step 6

« Last post by Ben on April 01, 2026, 07:50:42 PM »

 0.05vac and 29.69vdc @ TP1
0.077vac and .258vdc @ TP4