Memphis 16-mcd1000 voltage on output

[Solosound]

Hello DIYAudio Friends

Now I m checking an memphis 16-mcd1000
All the mosfets appear be fine.
Not visible damage in the amplifier.

The power source is producing + - 55V
The problem is when apply remote, the amplifier drain 1 amp, and after a few seconds, protect-on-protect-on-protect-on....it turn on.
See video:

YouTube - Broadcast Yourself

When is turn on...I put charge in the outputs, the amplifier come into protection mode.


I measure the output terminals and the positive have 55v !!

 

[timwebb]

U check the fets in the power supply out of circuit? The 640s fail fast too

 

[Perry Babin]

Pull the audio driver boards. Does the DC go away?

 

[Solosound]

I remove the 2 audio cards and it's the same problem what you see in the video.

the voltages in the TL494cn (with out the audio cards):
1.- 0.00v
2.- 4.8v
3.-0.05v
4.-2.5v
5.-1.4v
6.-3.6v
7.-0.00
8.- 12v
9.- 0.00 changing intermittently to0 .2V
10.-0.00 changing intermittently to0 .2V
11-.12.3v
12.-12.v
13.-4.5v
14.-4.8
15.-4.8v
16.-0.00v

Mosfets are solder but all measure ok.

No visual damage parts or bad solders.

I check the transistors and diode in the relay area, it´s OK about it. Thanks to Perry and the repair tutorial.

 

[Perry Babin]

Please don't use '-' as a separator. It looks like a negative sign and can be confusing where there could be negative voltage.

Do you still have DC on the tabs of the output transistors?

 

[Solosound]

Today the amplifier turn on without protection mode

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

 

[Perry Babin]

Reinstall the audio driver boards and remove the board just behind the RCA jacks. Do you still have 55v on the tabs or is it back to near 0 v?

If you still have 55v on the output, reinstall one audio driver board at a time to see if one or both boards cause 55v to be driven to the tabs of the output transistors.