2 Amp Problems

[The Poolman]

Amp is a Crate BV120H

1-The amp developed a hum, now the hum gets louder as I turn up the gain, I'm thinking one of my pre-amp tubes are toast...

2-The volume pot, does nothing from 0-2 but at 2 it gets really loud, louder that it should at 2. you can make very small adjustments to get the volume to back down a bit. New pot, or has some wiring gone wrong.

Everything else works fine on the amp. For the moment I have a Line 6 processor going in through the effects loop return to bypass the preamp. That works just fine.

What do you guys think?

[SixstringKing]

Answer to #2- New pot or try electrical contact cleaner

Answer to #1- Got me, could be a ground issue, florescent lights, any of your cables. If you have a spare pre-amp tube, try changing it out one at a time alternating between the spare and the ones in your amp. Obviously turning your amp off each time you do this.

[bratfink]

Try tapping each of the preamp tubes in turn (with a pencil - whilst the amp is on) to see if it makes it worse or better.

Does the hum go away if you run the input of the guitar into the return of the fx loop (i.e. not using the preamp stage)?

[Hellbat]

Pre-amp tubes are cheap and don't require any complex tweaking to change out. Buy a couple spares and try swapping them in and see if that solves your issue.

[tonemonster]

sounds right, I would suspect a bad tube on issue #1 try replacing preamp tubes with a known good tube, do one at a time moving thru them until you find that bad one. and I agree with the contact cleaner on the pots for #2. Tubes can cause some goofy problems, so I would suspect that first. but cleaning the pots is never a bad idea. I would say that should solve it, but if it dont I think its time to bring it to a shop.

[The Poolman]

Yeah, Im leaning towards preamp tube for number one, number two: I'll give the pot a good cleaning, if that doesnt help, I will have it replaced.
"Bratfink" there is no hum going in through the FX loop.

Thanks for the replies, much appreciated.

[bratfink]

If no hum going through the power stage only then you definately have a preamp issue.