MiniMoog Voyager V3.5 Stero Output only hums on Right Channel

[Brucifer]

HI

I am helping a friend diagnose a problem on his MiniMoog Voyager. Software says v3.5.

The unit works great on the mono out. However when I add a second amp to the right output for stereo, I get a distinctive humming sound that sustains as the left does, but only as a hum.
I plugged the headphones in and get exactly the same situation with sound in one ear and hum in the other ear.

I have looked through forums and it seems others have a variety of issues like this and mention a test procedure, but I cannot find that test procedure to fault find this problem. This could be something simple like a balancing pot somewhere or a resistor that has broken down.

Please note that I have done the basics of checking cables, checking the amp, opened the unit and looked for visible loose connections. Due to not being familiar with these circuits, I am hoping that I can get positive test procedures before digging in and maybe causing damage.

Thank you in advance
Bru

[RL]

Hi,
is the hum also hearable when the Voyager is off?

[Brucifer]

Hi.

No the hum is only audable when it is turned on. It also almost sounds like it is trying to play note.
If I left my finger off the key, it stops and as I depress the key, there is a distinct change in the hum similar to what I would hear in the mono left channel, but just a fuzzy hum .
Sorry to sound redundant, but trying to explain it better. If the output is from mono left and I have the key set with a sound is a 'bong' and then taper off, then I connect the output to the right stereo and the hum is a sharp hum and then it tapers off.
This is exact the same when I use headphones.