DC Offset issue with Adcom GFA-5500

[AcoustaKip]

Greetings,

I blogging to see if anyone has any suggestions with a problem I have with one of my Adcom GFA-5500 amplifiers. The symptoms I noticed was the right channel producing intermittent high frequency clicking sounds; it would produce this distortion after the amp warmed up for maybe last for 15 seconds then no distortion for maybe a half hour to several hours later. So I decided that I would adjust the Bias and DC offset per the service manual on both my amplifiers. I was able to adjust everything to spec except the channel that was producing the distortion; I was not able to get it any closer to 0mV then -17mV turning the trimmer to the limit. I tried turning it the opposite direction but that just made the value shoot down to -130mV. I thinking I'm going to remove the PCB from the chassis so I can check for cracked or broken solder joints; but I thought I would post here and see if anyone had any ideas or seen this issue before.

Thanks,
Shawn

 

[nigelwright7557]

I wouldn't be worrying about 17mV DC offset.

The amp needs a signal generator and scope attaching to see where the distortion is occurring.

 

[anatech]

Hi Shawn,
Look for a 10 ohm resistor from each supply located near the fuses. Replace with a higher wattage rating - but make sure they fit the board. Don't buy from other than a real distributor of parts. Those resistors usually go open, but yours might be at an in between value.

-Chris