#1
so I have this behringer 150w 2X12 and the master volume is very finicky and sometimes creates loud pops of static when moving it. also sometimes the volume doesn't response to changes in rotation unless the knob is tapped on, and if pushed slightly or sometimes with no provocation at all the amp will cut out or cut to a random volume for a second or two.

EDIT: forgot to mention that sometimes the volume will just gradually fade down till I tap on the knob, or it eventually starts cresendo-ing back

I'm getting a new amp for Christmas anyway but was wanting to keep this amp as a "jam amp" for my music room, and I've been wanting to use it for my college's jazz combo gigs, but I can't do that if the volume is unreliable.

from all the problems I'm guessing I need to replace the master volume pentometer. and I was wondering before I screw with anything if that sounded right to anybody with more experience than I

second I have never taken apart an amp, but I'm decent with a soldering iron, and have fixed solder joints in my own guitars, and soldered misc things with xbox/computers. I think I have the needed skills, but if someone knows something I don't please let me know
Last edited by Downfall360 at Nov 4, 2013,
#2
Sounds like you're on the right track. Shouldn't be too difficult, just make sure you know how to stay safe when working inside an amp. There are capacitors that store an awful lot of charge even after the amp has been unplugged. Know how to discharge and stay away from them when working on the amp and you'll be fine.
#3
Try some electrical contact cleaner in the body of the pot first. Cheap and easy before costly and difficult.
#5
A new pot is probably going to cost $10 or less and I would not call it difficult to install.

Sure, cleaning might fix the problem temporarily but once they get that dirty you're just delaying the inevitable. Might as well just replace it if it's going to be a gigging amp.
#7
Figured if it was a master volume it might be a dual-ganged. Might have to order one of those online and pay shipping.

And I did say "or less"
#8
cool thanks guys. I'll start trying to figure out the specific part I need and where to get it. thanks for the advice on discharge as well. I assume its the same as working inside other electronics right? wear an anti static bracelet or touch something metal and grounded before touching anything inside?

don' spose anybody knows what kind of pot is in a behringer gmx212, I can't seem to find it in the manual, and have yet to find it on google (I'm not giving up I'm reaching out to multiple sources at a times LOL)
Last edited by Downfall360 at Nov 5, 2013,
#9
It would be easier to open up the amp to see what kind of pot it is.

I never wear grounding bracelets when working on amps. Grounding yourself while working with or near high voltages is basically suicide. It is true that some amps may have some MOS devices in them, but people could argue either way.