Question about Yamaha XS-350 2-Channel Amplifier

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I have a yamaha amplifier in here for repairs, the model no is A500, i cannot get the speaker protect relay to come on, i have replaced all the transistors & capacitors in the speaker protet circuit to no avail, i,ve checked the outputs from the amp & all is ok, i,ve even replaced the relay, can u help

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  • peter857 Apr 14, 2009

    Hi Chaps, just came across this site and yes, I have a Yamaha A-500 (great Amp) with the same problem. Except the relay clicks in then clicks out after a few seconds. Just got a cct download and about to do some surgery after testing the DC offset at the output. Seems the speaker protection cct looks at the LH channel only? Any ideas what's wrong Dan?

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Measure DC to ground on the output transistors to check for any offset. The protect circuit is the least likely to be the problem. Post the readings here and I'll guide you from there.

Dan

Posted on Mar 11, 2009

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