Little problem with my poweramp

[pagemalicious]

So i changed the power tubes in my Peavey classic power amp. When i first played through it, the sound was fine and it sounded great. I turned it off for a bit so that i could put the power amp back in the rack case, turned it back on and now i get an annoying amount of hum. I can still hear myself through the amp but you can hear humming still. I know it's not TV's or computer monitors affecting it because i had them turned off. So it must be something else. Can any one help?

[Speiro]

What else is in the rack with it Steve?

[pagemalicious]

It's just my mp-1

[Wayniac]

Sounds like it may be a ground issue with the rail in the rack?

[Speiro]

Check the earth connections in the plugs for starters, my mp-1 didn't even have an earth wired when I got it, maybe somethings moving and coming apart when it's going into the rack?

[pagemalicious]

I changed the tubes around in the poweramp and now it's working fine. God knows how i got it fixed

[pagemalicious]

Ok turns out that the Rack case is causing the humming. Wtf? how the hell does that happen? i realised what was going on when i tried screwing it back in. Losen the screws the hum goes, tighten them and it comes back again. How the hell do you fix that?

[Dreamland_Rebel]

get a rack rider or furman power conditioner.

[Wayniac]

They sell washers that islolate (insulate??) the rack screws from the rack...
Or, you can try a plastic washer on at least one screw of each piece of gear in your rack... sort of a ground lift that may stop the loop.
Also - make sure to leave at least 1 space between the preamp and poweramp.