"Anatoly" wrote in message
...
Hi,



I am trying to fix RCA STAV 4090 amplifier that is a clone of Pioneer
VSX-D710. It is 5 channels unit that is using Pioneer's PAC011A and
PAC010A integrated amplifiers.



When I got it, it had a blown fuse in the ground rail of power supply
chain and filter capacitors in +VL and +VH rails were fried and leaked.
After replacing capacitors and fuse, amplifier has +12 V offset on the
power supply ground, amplifiers output is 0V.



When I am connecting speakers it works, but starts to overheat -- DC
current protection seems to be blown. Also there is a strong 60-120Hz
noise in all of the channels.



The question is: how split rail supply ground is controlled? It is not
connected with the signal ground as in other schemas that I saw.



There is a part of the scheme that controls some "NECK" voltage that goes
to integrated amplifiers. It was contaminated with the acid from leaky
capacitor. Does it have anything to do with that? What this "NECK" stands
for?



Thanks,

Anatoly



I'll look over the schem when I get a chance - but I have seen bad eyelets
at the power transformer boards on Pioneers, a bad eyelet at the center tap
would let the ground "float" and could cause your problem.

Mark Z.