HELP with weird Tubescreamer Problem!!

[Jamezm]

Hi guys, I'm new here.

Anyway I'm in desperate need of some help here. I modded my TS9 to true bypass according to Robert Keeley's instructions (http://www.premierguitar.com/archive/monthly/pedal_power/0704.htm) and while it works fine with DC power, there's an excessively loud hum going on when I unplug the adaptor or use it with a battery. I touch the footswitch and the hum is reduced. Can anyone tell me what's going on?

Thanks a lot for any advice!

[Jamezm]

anyone?

[GREEN FUZ]

It sounds like a grounding issue. Check all your connections then check them again.

[Jamezm]

but DC power can eliminate ground loop?

[petemoore]

  but DC power can eliminate ground loop?
  not real sure about that, how it'd would work.
  I'm building a Spyder power supply, and it has 8xDC outputs, each made independant of the others...and that will break ground loops.
  But if you're having un-ground-ey noises in a TS alone, ground loops wouldn't be the thing I'd look for to elliminate.
  I'd look for a lifted ground, that could cause when you touch the box for noise to occur, the box IIRC on a TS is supposed to be grounded, that'd mean it'd stay solidly at ground reference point [0.0V], your symptoms indicate that likely the box's voltage changes when you touch it ='s open ground.
  That's where I'd start, test between all grounds [that'd include the enclosure.
  You might not need a full debug tasked out, but if you do, read the 'Debugging' thread.

[Jamezm]

I'm not really good with electrical stuff... can you explain more about testing the grounds? do I check for continuity? resistance?
btw can a faulty 3pdt switch cause this? Thanks for your time!

[Jamezm]