cyber twin help

[methodofcontrol]

hey guys,
i've got a cyber twin here that came on but there was no sound. i opened it up and found two fuses had blown just prior to the + and - voltage regulators. i replaced the fuses and one known bad regulator. (7915)
i can't seem to locate any shorted IC's, or gounding issues in the voltage lines.
so i went ahead and plugged it in (w/ proper speaker load) and the good news is that none of my fuses are blowing and everything appears normal. the bad news is i don't have any sound.
there is a "click" or "pop" from the speakers upon power up and power down. nothing out of the ordinary, but an audible little noise. i had all of the dials set to "5" give or take a notch, and i'm positive the instrument cable is good and my guitar's volume was up.
no noise from the strummed guitar. any thoughts?

[Enzo]

This is a complex amp system. It is solid state, so it doesnt need a load, but what better than a speaker to listen anyway?

So the fuses held, but do you still have the rails? 15v are they? With power on, look at all the op amp output pins. ANy sitting at DC? ANd of those, are any NOT drivign an LED or some other switching function? That is we are looking for signal op amps with DC on their outs.

How about the other power supplies? Got volts for the tubes? Heater, B+? If the display runs, we know the computer is at least trying.

A bad host board can kill the sound. Is the computer part running?

What is and what is not working? by sending outs and injecting in at the various points accessible, what stages of the amp function?

Many cables inside, any chance one was left off? ANy chance two swapped places?

[methodofcontrol]

hey enzo, should i be looking at all of the chips? or just the standard 8 pin ones?

[Enzo]

In regards to...? The 8 leg op amps need +/-15 - or is it 12?, whichever - om its supply pins and wants neither on its outputs. Logic chips run on +5 and ground. And so on, powr amp needs whatever it runs on.

Look to the fundamentals first, is my message.