Customer has (2) of these amps in for repair, this write up is for the 1st amp.
Customer explained the amp was working fine then one day they turned it on and it did not come on, no power light no protect light.
With the bottom plate removed, I checked the output FETS and the power supply FETS and found no defects. Next, I connected B+ and GRD to the main amp terminals and saw zero current draw. I then connected +12REM to the amp but the power supply did not start up. This amp uses a TL494 for the power supply PWM. I checked pin7 to verify GRD, that was fine. I then applied +12REM and checked pin12 (VCC) and there was only +0.6v where there should be around +12v. I found Q46 (PNP transistor) had a mild short between all 3 legs.
I replaced Q46 and the power supply turned on and began to build both rail voltages. I then checked the output and verified high and low side rail V and the output drive circuit was working as designed.