Adcom GFA-555II problem

[oscarav098]

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.

 

[anatech]

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.

-Chris

 

[oscarav098]

Thanks

I'll check them today and replace if they're bad.