Peavey Firebass 700

[Ampcat]

After the warrenty expired on my Firebass 700 the sound went to a bad, loud hum with no output. The light for the compression came on and stayed on. I suspected one or more of the output transistors or related emitter resistors. After inspection and meter readings found nothing wrong. Could the problem be in the compression circuit? Anyone have the same problem? I need help.

[Enzo]

Disconnect the speaker. Is there DC voltage on the output?

The power amp stage uses two power supplies, are they both present and clean?

The preamp uses +/-15 aslo, are both those present and clean?