Ground in Older Onkyo Rcvr.
 

Hello to NG:

Wondering if there are any Onkyo repair techs out there? I have an
older receiver (TX-DS777b) that has a ground loop problem-intermittent
hum in center channel (not volume dependent)-and an intermittent
crackling when in surround mode-even when no signal present. Symptoms
disappear if side of receiver is gently whacked. I sort of remember a
service bulletin about these ground issues in the TXDS series (ie. 575,
747, 777b, etc.) and there is some sort of a mod to install a secondary
ground strap. Since I don't work in an authorized Onkyo facility, they
won't tell me much.....any help greatly appreciated!

Marc