700 RB Gallien-Krueger

[lordnikon]

There is a great ground problem coming from the input. If anybody here has a schematic or has worked on one of these please let me know because that ground is seriously annoying and I don't want to damage anything.

[Mars Amp Repair]

can you describe what the great ground problem means? Hum with guitar plugged in...without...etc...I don't have the schematic where I am now, but might have it at the shop....glen

[lordnikon]

with or without the guitar plugged in, there is a significant ground from the input of the amp itself. with nothing plugged in when i was checking to make sure it was jus the amp it still had that classic ground sound, so when i touched the chassis I grounded it and there wasn't that problem.

[oc disorder]

I seem to recall that one of the main audio grounds to chassis is on
one of the rear loop or f/s jack sockets. Make sure the "jack nuts" are tight
and no sign of corrosion or anything that may not make a good ground.
Hum is the term used (when you don't know the words ) sorry old joke..
to describe a usually undesirable low frequency sound which may be caused
by a lack of a ground connection or inadaquate filtering/smoothing of a power supply. Usually it is at the frequency of the mains supply (power outlet) or
in more complex cases a multiple of it.
Just make sure the whole jack doesn't rotate and break any wires going to it
when the nut is tightened.
Usually Gallien-Krueger fit star washers to help stop the nut coming undone.
Sometimes I wish a few more manufactures would do the same...!

[lordnikon]

i tried tightening the nuts. but it still has the same ground problem. it has to be the ground from the input to the chassis. it's more prevelant with a bass plugged in but no matter if it is or is not plugged in there is a ground problem at the input only.