problem with the performer 650

[JC@]

This amp came in completely fried and beaten.
Because of a very higher value fuse replacement, all the power amp section was gone badly: power transistors, and all of the diodes and zener diodes around it were physically broken.
Now the funny thing that's driving me nuts is that I have good signal at pin 1 in U4A, good signal at pin 6 of the U7, good signal in both power transistors, BUT just a tiny almost inaudible signal at the speaker connectors.
If I plug the signal generator in the effects return, same thing, so the problem is definetely not in the "preamp".
I have ckecked all components around the power section and all appear ok or have been replaced for good ones.

And here I am... completely lost once again.
Any help?

[Twist]

Compare the signal at pin 6 of U7 to the junction of R96 and R97. It should be about the same amplitude. If the darlingtons blew they most likely took out the emitter resistors. This may be a stupid question but did you check the speaker for damage.

[JC@]

...If the darlingtons blew they most likely took out the emitter resistors. ...
And they did.
They could be about the only components in the whole amp that I didn't check.
They had continuity, yes, but they had drifted to 130K or so.
I owe you a few beers now.

[Twist]

Glad you got it going. I've done the same thing before.