26

AB528 Microphone preamplifier / Re: Preampli AB528

« on: June 09, 2024, 09:56:07 AM »

Voyez-vous le signal sur TP4 avec le voltmètre en alternatif, par rapport au 0V.
Le maximum que je mesure est 5 mV.

Même question pour TP3, TP2 et TP1.

27

AB528 Microphone preamplifier / Re: Preampli AB528

« on: June 07, 2024, 05:40:17 PM »

Voyez-vous le signal sur TP4 avec le voltmètre en alternatif, par rapport au 0V.
Quelle est la tension continue sur la vis des transistors de sortie Q5 et Q6, par rapport au 0V.
Vérifiez les connexion du transfo de sortie.
Vérifiez que vous n'avez pas laissé le commutateur de polarité sur la position centrale (=mute).

28

MP573 Microphone preamplifier / Re: MP573 general power check and deviating DC voltages

« on: June 07, 2024, 05:32:53 PM »

The transformers are OK.
There is something wrong around Q4, Q5, Q6.
Check all the solder joints around there.

29

First Aid / Re: Need help with 573EQ, solder on gold connectors

« on: June 01, 2024, 06:09:56 PM »

Just remove as much solder as you can with a desoldering pump or solder braid.
You won't be able to restore the gold layer but it should still work.

30

MP573 Microphone preamplifier / Re: MP573 general power check and deviating DC voltages

« on: May 31, 2024, 11:30:39 AM »

Can you do the measurements shown here : DC voltages, and output transformer check?
We will add a new relay to your new order.

31

MC624 Monitor Controller / Re: Problem with headphone outputs on MC624

« on: May 23, 2024, 10:04:01 AM »

There is something wrong in both channels.
The pins 6 & 7 should be at 0VDC.
Does it change something in the voltages if you remove the ribbon cables going to CN24 and CN25.
What are the DC voltages on TP9 and TP10, against 0V? Should be 0VDC.
Same question after removing U6 and U8 but with a wire connected between pin 7 and 0V.
Look for bad solder joints or solder bridges in the area U6 to U9.

32

MC624 Monitor Controller / Re: Problem with headphone outputs on MC624

« on: May 21, 2024, 04:14:27 PM »

Do you have this issue in both ears?
Please report the DC voltages on every pins of U6 and U8 against 0V.

33

CP554 Diode bridge compressor / Re: Attack times

« on: May 21, 2024, 04:10:20 PM »

The front pannel attack times are more realistic in the 6 or 12 ratios.
In the lower ratios they are slower because they depend on the side chain signal level and this is by design.
The CP554 1ms position matches the originial Neve circuit which doesn't have an attack time switch. 
You can reduce all the attack times proportionnally by reducing the value of C37 but this will increase the distortion in the lower frequencies.

34

MP573 Microphone preamplifier / Re: Where to check for faulty transormator?

« on: May 21, 2024, 12:36:45 PM »

I think you should statrt here: https://www.soundskulptor.com/forum/index.php?topic=5.msg5#msg5

35

MU524 Vari-Mu Tube Compressor / Re: Very low sound from unit after working properly for weeks

« on: May 20, 2024, 11:15:28 AM »

36

MU524 Vari-Mu Tube Compressor / Re: Step 8 in the calibration instructions

« on: May 20, 2024, 11:15:09 AM »

37

MP573 Microphone preamplifier / Re: No Output

« on: May 20, 2024, 11:14:00 AM »

Try to follow the signal as shown here.

38

DI503J Triple DI and Re-Amp / Re: Extremely low output

« on: May 20, 2024, 10:26:46 AM »

39

MU524 Vari-Mu Tube Compressor / Re: Very low sound from unit after working properly for weeks

« on: May 17, 2024, 11:49:41 AM »

Please do the voltage checks described here:
https://www.soundskulptor.com/forum/index.php?topic=347.msg1907#msg1907

40

MU524 Vari-Mu Tube Compressor / Re: Step 8 in the calibration instructions

« on: May 17, 2024, 11:48:08 AM »

TR1 is a 2k trimmer so the marking 202 is correct (the third digit is the number of zeros to add).
The partslist is correct. Where did you see 203?

Were you able to set the balance 1 in step 7 ?
Can you do the voltage checks described here:
https://www.soundskulptor.com/forum/index.php?topic=347.msg1907#msg1907

Check the component value and solder joints of R3, R4, TR1.

41

TS500 Tape Simulator / Re: Meter LED strange fault, D8 reacting like it is D13

« on: May 17, 2024, 11:33:31 AM »

With your DMM in diode mode, check the direction of all the LED's.
Look for a solder bridge somewhere.
If nothing helps, send us the meter for inspection.

42

DI503J Triple DI and Re-Amp / Re: Extremely low output

« on: May 13, 2024, 06:13:10 PM »

You can try to send a strong test signal (sine 1VAC) at the instrument input and check you can measure it

- on TP1 (against 0V) at the same value,
- between pins 2 & 3 of U3, attenuated to 80mVAC,
- on TP3 (against 0V) after preamp, level depending on preamp gain.

43

DI503J Triple DI and Re-Amp / Re: Extremely low output

« on: May 11, 2024, 05:57:07 PM »

So the preamp is working, right?
Maybe a bad solder joint :
Check the resistor R1, transformer T1, switch SW5, relay RLY4.

44

DI503J Triple DI and Re-Amp / Re: Extremely low output

« on: May 10, 2024, 09:29:51 AM »

Does the gain drop occur in all 3 modes?
Is there a difference in level when you turn on the preamp?

45

MP573 Microphone preamplifier / Re: MP573 unstable, volume drop

« on: May 06, 2024, 05:39:07 PM »

This sounds like a weak solder joint. I would first check things around the power transistor because the changes in time could be caused by the device getting warm.

46

CP4500 Stereo Bus Compressor / Re: CP4500 meter intermittently unresponsive

« on: May 06, 2024, 05:34:35 PM »

First, I would check the connections between the meter and the PCB, in particular the female connector on the PCB side.

47

CP4500 Stereo Bus Compressor / Re: Compression happening randomly

« on: April 29, 2024, 11:58:47 AM »

48

MU524 Vari-Mu Tube Compressor / Re: Cant find problem in my build

« on: April 29, 2024, 11:58:07 AM »

Your values on TP4 and output are good. The error was mine and I have corrected the values in this page. I am sorry for the confusion.
The noise in the output shown in your video comes from bad balance settings on trimmers TR1 and TR2.

49

MU524 Vari-Mu Tube Compressor / Re: Cant find problem in my build

« on: April 26, 2024, 04:27:09 PM »

The unrealistic output level of 22.67VAC could be caused by the DMM.
What says the dB meter in the changed conditions. It should show -6dB.
Have you tried to listen to the output. How does it sounds?

50

MU524 Vari-Mu Tube Compressor / Re: Cant find problem in my build

« on: April 23, 2024, 06:05:49 PM »

Your values look better.
It is only  the output AC volatge that seems a little high.
Are you sure about the input voltage of  1VAC? It should be measured with the compressor connected.
Check the total resistor value of P2, between the 2 side pins (remove U1 and U2 for this measurement).
Check the value of R16.