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

Any help would be greatly appreciated.

Thanks in advance.

Thanks for your reply Mike. After digging through the console, it turned out
that there were some bad caps, chips, and a grounding issue. Thank god for
test equipment.

Again Thanks,

Ozzie
"Mike Turk" wrote in message
. rogers.com...
I would first check the power supply outputs for ripple.

-mike

"OZ" wrote in message
om...
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

Any help would be greatly appreciated.

Thanks in advance.

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