OK, more or less messing around with an old amp I had in the pile. Not even sure what the issue was with it but I threw some regulated power to it and it seemed to eat all the power I wanted to give it on the bench with no speakers or input signal. I rolled up to about 5 amps, then decided it would probably take all it could have so I better grab the thermal.
the FLIR image clearly pointed out a rather hot spot. Thinking "that was easy", I probed the mosfets and pulled em. Now I am second guessing what I am looking at, probably because I don't repair audio amps every often and don't fully understand them.
The FETs in the pic are 75344 power mosfets. Power it fed to them directly from input power. The issue is B+ is connected directly to the drain, and ground is plumbed right to the source....???? What am I missing here? You fire those dudes and you have a dead short..?
I sort of think I am on the right trail by following the hot spot with the thermal but not sure what to make of this. So far the mosfets seem good. No obvious short anyway.
the FLIR image clearly pointed out a rather hot spot. Thinking "that was easy", I probed the mosfets and pulled em. Now I am second guessing what I am looking at, probably because I don't repair audio amps every often and don't fully understand them.
The FETs in the pic are 75344 power mosfets. Power it fed to them directly from input power. The issue is B+ is connected directly to the drain, and ground is plumbed right to the source....???? What am I missing here? You fire those dudes and you have a dead short..?
I sort of think I am on the right trail by following the hot spot with the thermal but not sure what to make of this. So far the mosfets seem good. No obvious short anyway.