11

MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« Last post by JPK on April 01, 2025, 11:03:00 AM »

Dead tube. Contact us here for a replacement.

12

MU524 Vari-Mu Tube Compressor / Re: something wrong with my build

« Last post by Mona on March 31, 2025, 09:01:08 PM »

Hi JPK, Rly is in the correct direction. I'm traveling now for 2 weeks, so I can't do the other checks when I'm back and the mu524 is not miraculously working I'll post again. Thanks so far.

13

MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« Last post by coostor on March 31, 2025, 08:13:21 PM »

Resistance is 8.9 kohm...

14

MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« Last post by JPK on March 31, 2025, 07:43:52 PM »

Measure the resistance of the tube heater between pins 4 & 5 (tube removed). You should get around 3-4 ohms.

15

MU524 Vari-Mu Tube Compressor / Re: something wrong with my build

« Last post by JPK on March 31, 2025, 07:37:43 PM »

Is RLY1 in the correct direction?
Can you measure the signal on U2 pin4? With and without U2 inserted.
Is U2 correctly powered on pins 5(-16V) and 6(+16V)?
Try removing BR1.

16

CP4500 Stereo Bus Compressor / Re: CP4500 - No output and incorrect voltages

« Last post by JPK on March 31, 2025, 07:28:54 PM »

Check if the voltage on R95 left pin moves with the Threshold pot. Should go from -12V to +12V

17

MP512 Microphone preamplifier / Re: LED activity reflected in sound

« Last post by JPK on March 31, 2025, 07:25:05 PM »

A sound clip could help me understanding.

18

EQ573 Equaliser / Re: 573 there's no audio signal when I select XLR.

« Last post by JPK on March 31, 2025, 07:23:53 PM »

Please report the DC voltages shawn in this post, against TP4.
https://www.soundskulptor.com/forum/index.php?topic=25.msg41#msg41

19

CP4500 Stereo Bus Compressor / Re: CP4500 - No output and incorrect voltages

« Last post by SKa on March 29, 2025, 05:06:31 PM »

Hello JPK.

Thank you very much for your help!
And sorry for the delay... I had some personal work to do.

So I did, what you suggest.
- Re-soldered the connections on potentiometer P1 and on connections CN1a and CN1b.
- Checked whether the DC voltage from the threshold potentiometer reaches R95 (left pin): Yes, it is between +11.8 and -11.8 V.
- Re-soldered the connections on U9, U10 and R36...R40.

But unfortunately, it is still 14.9 VDC at TP4 and a constant -14.6 VDC at TP13 (as described above).

Do you have any other ideas? I would be very happy. Unfortunately, I'm not making much progress on my own.

Thank you very much!!!

Cheers...
Stephan

20

MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« Last post by coostor on March 29, 2025, 12:01:29 PM »

Tube doesn't glow. Power up the lunchbox: 5,5 V then more to 6.2 V after 10 seconds.
Value, direction and solder joints of L1, L2, U6, C30 to C33, D9, R38, R39, Q4 are correct.