Pioneer GM-2200 amp, DC out..


I've got a Pioneer GM-2200 amp that I bought recently, it is not working as it should - gives DC voltage on both speaker outputs.

PCB looks ok, I can't see any burnt components.

Any pointers on how to find the fault?
It was 20 years ago since I last did any trouble shooting in electronics, so can't remember much about amps... Would appreciate some help.

Schematics and service manuals: