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gfa-555 one channel hot
gfa-555 one channel hot
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Old 19th September 2008, 04:25 PM   #1
garth64 is offline garth64  United States
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Default gfa-555 one channel hot

I recently noticed one channel on my amp's heat sink is extremely hot while the other channel is slightly warm; I don't know if its always been that way or something has happened. Any ideas on what can cause this and what I can do to correct? The amp is vintage 1988. Thanks.
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Old 21st September 2008, 10:27 AM   #2
K-amps is offline K-amps  United States
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Location: Indiana
If it is still playing music without distortion or hum, then it could be:

1) Abnormal load on one side.. shorted coils? Remove the speakers to see if condition persists.
2) Bias needs setting... check the bias on both channels ensure they are within 1-2 mVdc across the TP or across the emitter resistors for both channels. I forget the exact setting but 10mVdc across the tp seems fine as reference.

3) If Bias is ok, then One channel has some oscillation that would require a more indepth check up...
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