El miércoles, 25 de noviembre de 2015, 12:26:48 (UTC-3), escribió:
On Tuesday, November 24, 2015 at 6:10:30 PM UTC-5, wrote:
Put a scope on the outputs and look for very high frequency harmonics. Perhaps the system is working too hard on things you can not hear.

Dan

good point


logical seteps
is it actually getting hot?
if not, the thermal shutdown system could be faulty

if it is getting hot you need to figure out why....
there could be an ultrasonic oscilation in the amp
the quiescent bias current could be too high in the amp
there could be some kind of short or overload at the output of the amp, bad speaker?

have fun , fixing stuff is a great way to learn

Mark

Don't have a scope, best I can do is a DMM.

Just to clariphy, the audio from the amp gets cut abruptly. Everything is working like a charm, the sound isn't fading away or anything, and the suddenly it stops outputting audio. Everything else seems to be working.

In this case, the only thermally dependent element I see is the PTC100. The circuit surrounding the PT100 seems to be compensating the bias current of the power amp, though I do not understand it fully, if anyone can point to a source that explains how this circuit work it would be great. To me it seems very strange that it abruptly cuts out the sound.