software

I need help from you techie guys! A bit of background first:

I got hold of a 2nd hand SOldano GTO pedal which I knew was prone to hum but took the plunge anyway. I get it, sounds good, hums like hell!! This is well documented on the web, so I tried a few suggestions that were listed:

- swapping tubes
- change leads/guitars
- etc. etc.

Then I read an article by Mike Soldano saying something about ground points and that the pedal and amp should be grounded to the same point. He recommended removing the ground (Earth in the UK?) wire, which I did and this still didn't make any difference. I moved the units to different supplies and still no change.

Then a ureka moment. The pedal works without being plugged i.e. it passes the signal. Like this, the pedal produces a little hum but nothing bad. As soon as the mains lead goes in, it hums - whether the unit is turned on or not.

So, any ideas what this could be?

Thanks

Moog

anyone?