Got an amp for repair with completely blown up output stage. Replaced all output MOSFETs. Amp powers on, DC offset is around 1.5mV. Music plays from the speakers, but as soon as I raise the volume (and this is not loud at all, speakers just hardly audible), the amp goes into standby and displays an overload error message. Looking at the amp’s manual, this message comes up if there’s a short in the output. Looked everything over and can’t seem to find any problems. Just looking for any suggestions, or something that I might have overlook. Thanks guys.
Sounds like an overload on the feed to the output devices ---or the ht for the output devices needs adjustment.
I would check the protection circuits. Quite possible they were damaged when the outputs blew and are triggering at the low level you describe.
It was a stuck relay. I guess it welded shut after the output blew. I banged it with a screwdriver several times and it became unstuck and now everything’s working great. The relay is installed to where it shorts the output during a catastrophic meltdown, I assume to protect speakers.