601

MP573 Microphone preamplifier / Re: MP573 STOPPED AFTER 2 WEEKS OF GREAT SOUND

« on: March 08, 2022, 12:35:17 PM »

Is the battery of your DMM OK?

602

MP573 Microphone preamplifier / Re: Calibration

« on: March 07, 2022, 05:53:51 PM »

You can temporarily wire a 2k or 5k linear potentiometer in place of R21 (not R22 in this case) and adjust the value to get the same gain at minimum rotation. Then replace the measured value of the pot by a resistor of the closest value.

603

MP573 Microphone preamplifier / Re: MP573 STOPPED AFTER 2 WEEKS OF GREAT SOUND

« on: March 03, 2022, 09:09:20 AM »

Can you measure the primary resistance of the input transformer, between pins 2 & 3 of the input XLR, with power on, impedance switch on 1200 and 600?
It should show 48 and 12 ohms.

604

MP573 Microphone preamplifier / Re: Calibration

« on: March 02, 2022, 11:29:45 AM »

This is surely due to the gain potentiometer tolerance which is 20%.
How many dB's of level difference do you get for the same position of the pots?
Is there still a difference for the extreme positions?
You could try to play on the value of R22 on one of the units to reduce the gain difference.

605

CP5176 FET compressor / Re: Why an OFF switch and not an ON switch?

« on: February 28, 2022, 09:20:05 AM »

whats the philosophy behind an OFF switch instead of an ON switch?
A label mistake!

What matters is the green LED:
When light is on, the compressor is working,
when light is off, the compressor is bypassed.

The bypass is a relay that connects input directly to output but the compressor still receive the signal and the meter keeps moving.

So your compressor looks perfectly OK.

606

LA502 Optical Compressor / Re: No compression

« on: February 28, 2022, 09:09:27 AM »

Make sure you didn't reverse the optical coupler OC1.
Check your solder joints on OC1, P3, R33.
Check continuity between OC1 LED+ pin (bottom low) and U6-pin7,

Check continuity between OC1 LED- pin (bottom high) and U6-pin6,
Check continuity between OC1  RES1 pin (top high) and R4 right,
Check continuity between OC1  RES2 pin (top low) and 0V.
If all is OK then you may have a defective optical coupler (rare). Contact me here and we will send a replacement.

607

News and updates / Re: Welcome to the Sound Skulptor forums

« on: February 25, 2022, 11:09:15 AM »

You need to register in order to post.
It's a shame, but it's unavoidable so as not to be flooded with spam.

608

LA502 Optical Compressor / Re: Meter LEDs -12, -16, -20 are not lightning

« on: February 18, 2022, 04:03:24 PM »

And when they are connected there is also a continuity between Cn1a 9 & Cn1b 7
I am not sure I understand.
Are you saying you also have a continuity between pins 7 & 9 on Cn1a (or Cn1b), when connected?

609

LA502 Optical Compressor / Re: Behavior of the GR-LEDs has changed

« on: February 16, 2022, 08:55:29 AM »

Are there really bad solder joints that repair themselves?
Yes, with a little shock.

Is 16.16V ok? The setup guide says 15-16V?
Yes OK.

But would it be possible for you to provide me with a small WAV track including setting and level values for the compressor?
That would not work because every converters have their own dB to Volts relationship. The only reference can be given by a voltmeter.

Now there is always the possibility for you to send us the unit for repair. Contact us here.

610

CP5176 FET compressor / Re: Resistor R57 burned on setup guide ..

« on: February 16, 2022, 08:48:10 AM »

Did you double check the power transistors not being swapped? It is a very frequent mistake.
Also are you sure that the 4 solders on each vertical PCB are making good contact. This also can make the resistors burn.
Does the LED light up?

611

LA502 Optical Compressor / Re: Meter LEDs -12, -16, -20 are not lightning

« on: February 15, 2022, 03:37:32 PM »

It also seems to exist a signal continuity between Cn1a 9th pad & Cn1b 7th pad.
Is this true when the connectors are disconnected? There should only be a connection between 6&9 on CN1a and 4&5 on CN1b.

612

LA502 Optical Compressor / Re: Behavior of the GR-LEDs has changed

« on: February 12, 2022, 10:46:34 AM »

It looks good.
You probably had a bad solder joint that fixed itself.
I would go again through the setup of the GR meter.

613

LA502 Optical Compressor / Re: Meter LEDs -12, -16, -20 are not lightning

« on: February 12, 2022, 10:00:12 AM »

You can verify the CN1a/b connector with your ohmmeter by checking the continuity from the bottom pads on the main PCB to the top pads on the LED's PCB.

614

LA502 Optical Compressor / Re: Meter LEDs -12, -16, -20 are not lightning

« on: February 11, 2022, 11:41:24 AM »

Try swapping U8 and U9 to see if the issue moves to the 3 other LED's.

615

LA502 Optical Compressor / Re: Problème de setup LA502

« on: February 11, 2022, 11:39:01 AM »

J'ai fais beaucoup plus de 20 tours sur les trimmers, je ne sais pas si ça pose un problème?
Non, aucun problème.

Etes-vous sûr de bien avoir le 1 VAC sur l'entrée, avec le compresseur connecté ?
Quel est le numéro de révision du PCB ?

Entre TP2 et la sortie, il n'y a que le transformateur. Assurez vous que vous faites bien la mesure en différentiel,  entre les points chaud et froid de la sortie.

Vous pouvez vérifier les resistances des enroulements du transfo :
- Primaire entre TP1 et 0V : 5 ohms
- Secondaire en différentiel sur la sortie : 23 ohms.

616

MP573 Microphone preamplifier / Re: Problems setting up the MP573 - General power check

« on: February 11, 2022, 11:22:53 AM »

We are measuring it directly from the PAD.
Sorry, what is the PAD?

Remove U2. In order not to destroy any via or track, you must heat the 3 pins together with a large blob of solder.
Next mesure the DC voltage on the center pad of U2. If it is back to 14-15V then the issue is probably not in U1.
Replace U2 by a short (see attach pic) and briefly power up while monitoring TP2 voltage. Do not leave the power too long because the circuit will be overvoltaged.
If TP2 is still near 0V then the issue is probably not in U2.

(Or contact us for a workshop return)

617

LA502 Optical Compressor / Re: Meter LEDs -12, -16, -20 are not lightning

« on: February 10, 2022, 06:20:34 PM »

All good.
Check that you didn't reverse one of the LED's. You can do this with the DMM in diode position, it will light up the LED when connected in the right direction.
Check that there is continuity between U8 pins 5, 7, 9 and U9 pins 5, 7, 9.

618

MP573 Microphone preamplifier / Re: Problems setting up the MP573 - General power check

« on: February 10, 2022, 04:12:10 PM »

Are you taking the 0V reference on the test pin at the back of the PCB?
There must be a short somewhere in the circuit. Look for a solder bridge somewhere. Is there an other component that gets hot (out transformer disconnected).

619

LA502 Optical Compressor / Re: Meter LEDs -12, -16, -20 are not lightning

« on: February 10, 2022, 03:39:44 PM »

What are the DC voltages you get on both sides of R37, against 0V.

620

LA502 Optical Compressor / Re: Behavior of the GR-LEDs has changed

« on: February 10, 2022, 03:36:38 PM »

Check value, direction and solder joints on U7, U8, U9, R36, R37.
What are the DC voltages you get on the 2 sides of R36, against 0V.
What is the revision number of your PCB?

621

MP512 Microphone preamplifier / Re: connector missing

« on: February 10, 2022, 12:20:29 PM »

Correct.
The jumper JMP1 forces the XLR input. It is only to be used during initial testing without the DI board installed.

622

LA502 Optical Compressor / Re: Meter LEDs -12, -16, -20 are not lightning

« on: February 09, 2022, 11:24:51 AM »

Check value and solder joints of R36, R37, U7, P7, P8, P9, U9.

623

MP573 Microphone preamplifier / Re: Problems setting up the MP573 - General power check

« on: February 09, 2022, 11:17:08 AM »

The current limiter U1 sees too much current 
Can you measure the ohmic resistance
- between the case of U2 and 0V,
- between the case of U2 and V+ ?


Do you also get TP2 near 0V when the output transformer is disconnected?

624

MP573 Microphone preamplifier / Re: Problems setting up the MP573 - General power check

« on: February 08, 2022, 09:41:50 AM »

Is U1 getting quickly very hot after powering?
Same question for U2.
Can you measure the ohmic resistance
- between TP2 and 0V,
- between TP2 and V+ ?

625

MP573 Microphone preamplifier / Re: Problems setting up the MP573 - General power check

« on: February 07, 2022, 11:16:31 AM »

but my voltage is 0V at TP2
Verify you don't have a short circuit between TP2 and 0V.
Check the voltage (against 0V)
on the anode of D4 (should be -15V),
on the case of U1 (should be -15V),
on the case of U2 (should be -15V).

The jumper on CN1 is on the wrong pin.