working on this solid state powered mixer - main issue is i cant find a schematic anywhere so its a bit hard to troubleshoot it. its having a strange problem:
the output is nice and powerful, but once it gets to a certain volume, it starts to experience a periodic drop - every 1.5 seconds or so, the volume will dip between full power and 1/8 power - almost like a very slow tremolo. ive traced the problem to the power amp - it does not appear in the main preamp out, but does appear throughout the power amp. it only happens with a load plugged in - if i scope throughout the amp, all the way to the output transistors, when its unloaded, it works perfectly. but once a load is plugged in, the power amp seems unable to maintain full power.
now whats hard is that without a schematic i cant quite trace it properly - i was just wondering if anyone has a thought what might cause such a strange symptom?
its a long shot but anyone seen a schematic for this thing around??