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Old 9th November 2005, 02:11 PM   #1
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Join Date: Nov 2005
Default Adcom GFA-555II problem

Hello all,
I have a 555II with a ground problem. The amp is overheating,when I measured the bias voltage it was extremly high on both channels. I tried to lower it but had no success. Then I measured the ground at the RCAs and nothing. I solder a temporary cable to the RCAs ring and grounded it and the problem was fixed but this is obviously not the right way to do it. I like to know if anybody around here has had this problem and if so what's causing the problem. I do have the service manual.
Thanks to all.
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Old 10th November 2005, 01:02 AM   #2
anatech is offline anatech  Canada
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Join Date: Jun 2004
Location: Georgetown, On
Hi oscarav098,
Check R104 / R154. They are 100 ohms from the signal common to ground. They may go open if a differential voltage appears between the inputs and chassis ground.

Replace with the same parts. Carbon film is original, you can use metal film if you want.

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Old 10th November 2005, 03:47 PM   #3
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I'll check them today and replace if they're bad.
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