2:90 Very Bad hum

[whackmaster63]

I just pick up a mesa 2:90 power amp, Im running a Peavey Rockmaster
Im getting a lot of hum from the 2:90, Is this normal?? I tapped my hand on the amp and got some popping noise, Any tips ???

 

[sombra]

How could be a hum normal ?!
If the problem isnt in the peavey,call mesa they could give you the best answer .
Anything here is just guessing.
luck

 

[mARKw]

Try connecting straight into the 2:90 one channel at a time from your guitar. Make sure the other channel is turned down (and presence all the way up i think) See if it still hums.

I had a big hum to start with but it was coming from some faulty electrics in my JMP1 preamp. Maybe the 2:90s just accentuate faults in other equipment (I don't know)

I've just started having trouble with the 2:90 blowing fuses - I'm praying the power conditioner (on order) will fix it :?

Good Luck

 

[whackmaster63]

Hey thanks for the help, Seems like the trannys getting pretty hot, im gonna take it to a local shop in town that carrys boogie

 

[mARKw]

Good luck. Let us know how you go.

:?:

 

[steveohdearyme]

mARKw, im also having problems with my 2:90 blowing fuses. I take it this doesnt always neccesarily happen when a valve goes?

According to the Mesa tech, my 2:90 works fine and has a great level of output. Ive blown a valve already though which has been replaced, now ive got a problem with my fuses going....

 

[mARKw]

Bizarre, hey. I am waiting still to get my 2:90 back from the shop to see what the problem is. If he says there are no problems then I'll be hitting them up for a new amp I think. I'll keep you posted.

 

[steveohdearyme]

Nice one dude, thatd be much appreciated!

Awesome sound from your band by the way man, some serious rockin' going on!

 

[whackmaster63]

Mine seems to be quiet untell i plug my rockmaster
preamp into it, ive also blown a tube, It seems to be working ok now

 

[mr_fender]

Is it limited to the left or right channel or in both. I would check the tubes. Not just the power tubes, but also the 12AX7 tubes inside the chasis. I once had a similar issue with my 2:90 making all kinds of weird noises in one of the channels. I tried changing power tubes for that side, but it didn't help. Turned out to be a bad 12AX7 driver tube inside the chasis. I swapped it out with a new one and my baby was purring like a kitten again. Good luck.

 

[E_R]

I thought when your amp hummed...you were supposed to teach it the words......????



Yeah I'm no help.

 

[whackmaster63]

Ok so i open up my 2 90, and one of the presence pots is loose, The pot moves, Will this be an expensive fix, Wonder if this is were the hum is coming from. Acting wierd, I put i my rack and it get 60 cycle hum, i take it out and its quiet

 

[triodal]

i think the pots is missing a washer behind.

Ground lift?

 

[Tuna141]

Acting wierd, I put i my rack and it get 60 cycle hum, i take it out and its quiet

Sounds like a ground loop problem to me. When you install the power amp into the rack/case, you ground its chassis to the other pieces in the rack. This is most likely causing your hum. The first thing to try is lifting the ground on any devices in your rack that have ground lift switches. This may cure your problem. If that doesn't work, then you need to insulate the power amp from the rack, or the other conflicting device in your rack that is causing the ground loop.