Giving the model number would be useful.

I would suspect probably an edge connector problem or dry joint on a
board.(after the volume control so follow the leads from that to the tone
board or main board).
Its unlikely to be the amp channel itself or the amp protection would have
detected a problem and cut out.

AW

"ElectroNovice" wrote in message
oups.com...
I have a Yamaha amplifier that's about 5 years old. The right channel
is normal, but the left channel has a low hum and significantly reduced
sound volume/quality.

I've tried the following:

Switched speakers- Not a speaker problem.
Switched from A to B speaker output- no change.
Tried multiple audio sources and input jacks- Not a source or input
jack problem.
Tried headphones- Same results as speakers. Hum and low volume, low
quality sound.
Tried changing DSP program modes- hum stays the same in bad channel,
sound changes as it should in working channel.
Tried adjusting all knobs including balance- no effect other than as
expected.
Tried all switches off/on- also no effect other than as expected.


Notes:
The hum exists even if no audio source is connected to the unit.
The hum does not increase or decrease when I move the volume knob.
The tone of the hum changes when I switch into the mode that lets you
change the volume of five speaker output channels (front, rear, center)
and when I switch from one channel to another.
Adjusting the volume of channels otherwise has no effect.

I am a newbie to electronic repair but can read and follow directions
and am willing to use this amp to learn on. I don't have any test
equipment but would consider buying or borrowing it.

Any help would be appreciated!

Thanks-