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Stereo amp's one-side failure during long warmup. Thereafter side is unreliable.

One output channel (the right) on this older but still excellent amp won't play during the first perhaps 30 minutes of warmup and use; then it plays intermittently; and eventually it seems to play steadily--but must be considered unreliable.

It there an easy fix, something easy to replace, or it this a "cost more to check out than it's worth" situation? Shame to toss this fine old box, but must be practical.

What do you think? (I isolated the problem to the amplifier via changing inputs, outputs, earphones, speakers, etc., and using all face controls.)

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Re: Stereo amp's one-side failure during long warmup. ...

Hi Randyhath. Intermittent problems are usually the result of cracked solder joints somewhere in the circuit. No components need to be replaced - a good thing. Are you handy with a soldering iron?

Look at the transistors or components that are screwed to the heatsink (metal plate for cooling). If you can see little crack rings around the component legs, you have found your problem. Resolder the joints and you should have a reliable amp.

Posted on Nov 06, 2007

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Re: Stereo amp's one-side failure during long warmup. ...

Sounds like a failing capacitor in the power supply. When they are damaged, they will not charge properly. Eventually (about 30 minutes?) they will hold a charge and function at a percentage of their actual capacity. Look for bulging or leaking capacitors as well. This is a common problem in TV power supplies.

Posted on Apr 16, 2013

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