I’m going to show you how to fix PA or guitar / bass amp scratch volume pots in just a few minutes or less. This technique works on bad volume pots or faders in guitar amps, bass amps, PA heads, mixers, consoles, and just about everything else with an analog volume pot.
I bought a used Peavey PA-400 PA head a few weeks back for my band. I wanted to use it on stage to power our monitors, and I could also use it at band practice if I ever needed to. I found it on Craigslist, the guy wanted $125 for it, and I offered him $75 and he took it. I say it was a pretty good deal for a built-like-a-brick-shithouse piece of gear, and it’s 210 watts RMS!
Here’s a pic of the PA head:
When I was at the guys house picking this up he demo’d it for me quickly with a mic and he told me it worked great but the volume pots were a bit scratchy. I got it home and plugged it into my mains and low and behold – every single pot on this unit was scratchy! Some of them sounded like nails across a chalkboard – it was pretty bad.
I unscrewed the front panel only to find out that this unit was actually hand-wired (jackpot!). You sure don’t see any gear other than very expensive boutique equipment hand-wired anymore! The first thing I did was blow the whole thing out with a bottle of canned air. I was surprised that it wasn’t any dirtier than it was, considering this amp was probably made 1980-81.
So, my next job was to clean out all the volume pots. To do this you need a can of “DeOxIt” (de-oxidizer), which you can get at nearly any electronics shop, sometimes radio shack, guitar center, some music stores, or online (look for the link at the end of this post). On the back of all volume pots have a little hole. sometimes it’s kind of near the edge or on the side. Most spray cans (like WD-40) have a little straw you can insert in the nozzle, and this hold is normally about that big.
This is also a good time to mention to NEVER – EVER use WD-40 to fix volume pots – EVER!! It may work at first, but WD-40 gets sticky over time. Within a year your volume pots will be bad gain! Always only use a de-oxidizing spray specifically made for the purpose of cleaning dirty volume pots! This is what a can of DeOxIt looks like:
In the next pic you see me gently squirting a VERY small amount of DeOxIt into the backs of the volume pots on my new (used) PA-400:
Be sure to very gently squirt a single time into the volume pot and then (from the outside) rotate the volume pot quickly all the way on and off about 12 times to work the fluid in as much as you can. It should get very easy to turn after just a few times. Do this on all your volume pots.
If you didn’t squirt too much fluid in – you can usually fire your amp back up within 15 minutes. If you “over-sprayed” – you better hold off at least 24 hours. After I cleaned out my pots and put the panel back on – I fired up my PA head and it was good as new! It was loud as hell and not a single volume pot had any problems at all! I’m glad I did this myself because it probably saved me $50 at the repair shop!