Banish Intermittent Connections, Crackles And Pops With Contact Cleaner
By Phil O'Keefe
Sooner or later, everyone who plays electric guitar or bass will run into a scratchy control or intermittent jack on an instrument or pedal. While this is occasionally intrinsic to the circuit design (the ZVex SHO boost pedal is famous for its "crackle okay" labeling on the volume knob), most of the time, crackles and "static" when you adjust a control is due to oxidation, corrosion or dust and debris buildup that is affecting the electrical contact between the pot's internal contacts or the various parts of the plug and jack. In some cases, the surfaces are just so old and worn that you have no choice but to replace the pot or jack with a new one, but most of the time, a simple cleaning is all that's needed.
Cleaning a scratchy volume pot on a pedal or guitar is fairly easy. Get yourself a can of Caig Deoxit (Figure 1) - it's a contact cleaner, lubricant and all-around miracle worker in a can. Open up the device with the scratchy pot. Most pots have a small opening on the side close to where the three solder lugs are located.. (Figure 2) Aim the tip of the red extension nozzle into that gap, and give it a decent 1 second blast of the contact cleaner. Immediately "work" the control back and forth quickly several times, turning it all the way up and down. The excess cleaner will probably drip out of the control - using a small rag beneath the pot to catch it will help keep things neat and tidy, but if it hits some of the other parts, it's not likely to hurt anything; especially if you give it some time to dry before reassembling everything and powering it back up.
Figure 1: Caig Deoxit contact cleaner
While I'm "in there" and the device is already disassembled, I'll clean the other control pots and contact points too, even if they are not noisy. A little extra preventative maintenance at this point will reduce the possibility that you'll have to reopen the thing to fix something else later.
Figure 2: Most pots have an opening on the side near the three connection lugs that you can spray the contact cleaner into
Remember, it only takes a little - you don't need to drench it. A 5 oz aerosol can of Deoxit, which contains over a thousand applications, should last you quite a while, even if you use it frequently. And I do - it's great stuff! Keeping those contacts clean will result in better electrical contact at the patch points, fewer sonic gremlins and noise, and a better sounding and more trouble-free setup overall. For those reasons, I also like to occasionally clean my patchbays, mixing board I/O jacks, insert points and faders, effects pedal and rack module input and output jacks, as well as all of my patchbay, mic and guitar cable plugs too.
A word of caution - for amplifiers and anything else that's AC powered, refer servicing to a qualified tech. Long after they are unplugged, tube amps can still store enough residual electricity to give you a lethal shock, so play it safe and stay out of the inside of any box you're not qualified to work on safely.