Memphis 16MC500d

[Bills amps]

I have two of these amps with the same problem. Both came to me blown. Both amp output fets and power supply fets burned. Also the power supply driver board had failed driver transistors so I replaced them.
With just the power supply driver board installed the amp will power up. Has rail voltage and both +\-15 volt supplies. Rail voltage is +\- 60 volts.
But if either of the other boards are installed the amp will not power but will pulse between green and red.
I have also replaced the both oamps and both the MC14060BCP and LM316n ic's.
Thoughts on this please
And thank you.

 

[Perry Babin]

Leave the audio PWM board out.

With the audio driver board in, do you see pulsing DC on the tabs of the output transistors?

If so, is the pulse positive or negative?

 

[Bills amps]

No pulsing voltage on the outputs

 

[Perry Babin]

Which output pins on the two LM393s on the power supply board toggle as the LEDs change from green to red?

 

[Perry Babin]

If you don't have anything better, the following power supply schematic may help.
http://www.bcae1.com/temp/infinity - REF611asm.pdf

 

[Bills amps]

now i have the amp powered up. but has 51volts on the outputs.

 

[Perry Babin]

What did you do to get it powered up (may be helpful to others)?

If you remove the driver board for the audio, does that eliminate the DC?

 

[Bills amps]

To get the amp to power on I put the correct driver board in. I had mixed them up when comparing the two that i have. Hate to admit that but I am not perfect. There was a extra pin on the board that missed my attention.

And to answer your question on removing the audio driver board does the voltage go away. Yes. no voltage on the speakers once removed.

 

[Perry Babin]

You could have a leaky, shorted or open driver. The low value resistors on the emitter of the drivers also fail. Also confirm that the Zener diodes D841 and D851 have 12v across them when the amp is powered up (may have to repair other driver board issues first).

 

[Bills amps]

the transistors were good as well as the resistors. the voltage across the zener diodes was 51volts. still have issues elsewhere. Ideas?

 

[Perry Babin]

The voltage measured directly across the two zeners should be approximately 12v.