OZ wrote:

Hi All,

I am having nosie trouble with my trident 80 series console. I can no
longer wait for a tech here in Chicago. The problem I'm having is a
hum on the two buss. There is no equipment connected to the console
only speakers. With all modules removed the hum is eliminated and with
any one module re-inserted the hum re-appears. Also, on pin 2 on the
opamps(TL071,NE5534) socket on the Echo return module, there is a
-3.3v current present with the opamp removed from the socket.

By looking at the a schematic can anyone determine if voltage should
be present at pin 2 with no audio signal.

http://www.sandstorment.com/images/remix.jpg

Pin 3 ( non-inverting input ) is tied to ground, therefore feedback action
via R248 ? ( the number isn't clear ) should maintain Pin 2 also at ground
voltage - the classic virtual earth mix amp.

Suggest you check volts on Pin 3 too to check it has continuity to ground
- if socketed, there's a possibility that there may be a poor connection
due to ageing/vibration.

I see that more than one bus amp is affected - maybe the ground connection
is poor.

Graham