I have a Behringer PMX2000 PA head that won't power up when the power switch is turned on. It was working fine until turned on one day and it made a loud "POP" through the speakers and everything went dark.  All fuses are ok. Power cord, power switch, power supply caps, and thermal protection all test good. No obvious burnt traces or comonents. Any ideas? 

Also, Behinger doesn't supply schematics or allow them to be posted on the Internet. Anyone with a schematic for the power section of this amp please feel free to email me the schematic anonymously at dgushue(at)att(dot)net. It would really help me in testing voltages at various points. Thanks.