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Pioneer VSX-D710 amplifier repair

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

Reply to
Anatoly
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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.

Reply to
Mark D. Zacharias

Mark,

Thanks for the reply. I did check the center tap wiring it is OK. The ground is not floating relative to power supply rails -- both high and low voltage rails stable and correct. The power stage ground is offset relative to the amplifier signal ground. It is a kind of weird "floating" ground power stage power supply scheme.

If you have scheme in electronic form, could you please send it to ab_pub@ snipped-for-privacy@yahoo.dot.com (remove at@ and dot.)?

Thanks, Anatoly

Reply to
Anatoly

The grounds dhould be the same - look closer at the eyelet of the little PC board where it connects to the center tap pin of the power transformer. Try resoldering the eyelets. One might curl up as soon as you heat it up and apply solder.

Seen it more than once on Pioneers.

I'll send that PDF.

Mark Z.

Reply to
Mark D. Zacharias

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