Oscillation in the Retrograde

[Mark0614]

Hi

I don't have the 2014 board but the previous one (I believe). The oscillation issue occurs when I turn the guitars volume down, the Retrograde goes into a low frequency (as far as I can hear) oscillation, it goes away when I turn the guitars volume up. I know it seems like a trival issue, but I like to know I have the effect working perfect before I case it up.

I have experimented with moving both earth wires from the input jack earth to the output jack earth, but it made no difference.

EDIT: I tried shorting the input and the noise went away, I tried shorting the end of the cable which is plugged into the guitar and the noise went away. I tried another guitar, and the noise was the same. I'll try another guitar later.

Has anyone come across this issue before and can you make any recommendations?

Thanks for your assistance in advance.

Regards

Mark