Rockford Fosgate 600a4

[S Merlington]

This amp will Power up and play clean audio for about a min then it will burn all 4 bias transistors Q105,205,305,405 ..

After it burns them I get full rail voltage measured directly across WA h speaker terminal for all 4 channels ..

I replaced them 2 times now and the amp will play clean audio after a min all 4 of them burn again so all 4 channels have excessive DC on the outputs ..

Everything tests good in each channel..

Any ideas on what I'm missing here ?

 

[Perry Babin]

What is the supply voltage to the op-amps?

 

[S Merlington]

I have -12.18

And it looks like the positive regulator has failed I have 26 volts on pin 8 of the opamps

 

[Perry Babin]

Correct that and see if they hold.

 

[S Merlington]

Replaced the LM317 and the bias transistors ..

So far the amp seems to be working correctly ..