Question about Adcom GFA-5802 2-Channel Amplifier

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Drop out of left channel, Adcom GFA5802

The amp works fine for a period of about 3 hours. At that time, the left channel becomes noisy and the signal dies. No errors indicated on front panel. Right channel continues to work fine. The noise sounds like 120Hz buzzing. It sounds like there is an open common on the input to the amp. When the amp cools down, performance is normal.

Joe

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It sounds as if there is a broken solder joint somewhere that slowly opens up with heat. The other possibility is that an input or driver transistor is dying. Since the whole channel is dying, I would guess the broken joint and/or dying transistor are near the very input of the channel.
A tech can very easily find the spot by playing the amp until it starts to die, then spraying small bursts of freeze spray, one component or area at a time, until the amp suddenly comes back to life.
 

Posted on Sep 26, 2008

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