By Craig AndertonFrom cleaning contacts to replacing capacitors, try these easy repairs for glitchy gear
Unlike a fine wine, electronic gear
Definition:
Musical or performance equipment. doesn’t always age well—you might pull out a unit that was working fine a few years ago, but no longer works. Don’t panic! The fact that it did work means the problem is probably not too severe, so one of these seven simple fixes may be all you need to help get your gear back into operation.
But first, remember this word: iatrogenic. It means an illness caused by medical examination or treatment, and it’s all too easy to have that happen with repairs! A dropped screw, a delicate plastic retainer on a ribbon cable connector that gets broken off, stripped screw threads, working on gear while it’s plugged in (even if the power switch is off), not wearing a grounding strap to avoid static electricity damage...be very careful when taking something apart and putting it back together again. Check for service manuals online, as this may help prevent an expensive mistake with gear that’s inscrutably difficult to take apart.
1. Bad Backup Battery
This one’s easy enough: replace the battery. However, remember that batteries can leak. One way to head off an expensive repair is to check internal backup batteries periodically to make sure they’re in good shape. A leaky battery can ruin your day (Fig. 1).
There are also two fine points. First, if you take the battery out to test it, the voltageDefinition:
Also called electro-motive Force (EMF). The "charge potential" or pressure of electrons that causes current to flow in a circuit. may seem fine; but when under loadDefinition:
The energy or capacity consumed by a device., it’s low. If possible, always measure the battery voltage with the battery connected. Second, battery connectors can sometimes get corroded. Scraping the battery connector slightly so that it’s shiny instead of dull may be all that’s needed to get the unit working again.
2. Blown Fuse
An external fuse is easy to check, but to check for internal fuses, you have to open up the gear. When taking the fuse out of its holder, be very careful not to break the glass shell. And when buying a replacement fuse, get two—and affix the second one inside the box (duct tape works great if the insides don’t get hot). Then the next time a fuse blows, you’ll have one handy.
3. Corrosion on Jacks
For some reason, this seems most common with RCA jacks, but can also happen with other types of connectors. With any kind of corroded metal-to-metal contact, Caig DeoxIT D5 (Fig. 2) is your friend. Many a piece of gear that seemed like it couldn’t pass signal came back to life by simply spraying contact cleaner into a jackDefinition:
A connector, normally female, that works in conjunction wit a plug. Usually located in a piece of equipment, or as part of a cable. and plugging/unplugging/rotating a plugDefinition:
A connector, normally male and attached to a cable. several times to spread the contact cleaner over the surfaces. Note that you don’t need to drown the contact in cleaner; a little goes a long way.
And here’s a bonus jack tip: if a 1/4” phone plugDefinition:
An audio connector with 2 or 3 terminals, commonly available in 1/4" and 1/8" diameters. The name comes from its original application in switchboards and routing patchbays. is left inside a phone jack, sometimes the phone jack contact stays in that “opened” position instead of springing back upon removing the phone plug. This can lead to an intermittent or inconsistent connection. Bend the jack’s contact inward, gently, so that it makes firm contact with plug tips.
4. Corrosion with Sockets
One of my most baffling fix-it jobs was an old synthesizer. Long story short: an integrated circuit’s pins were a dissimilar metal compared to the socketDefinition:
A female connector or receptacle. into which the pins inserted, and a small, crystalline, metal “hair” grew across two pins, shorting out the ICDefinition:
IC (Integrated Circuit): A complete, miniaturized electronic circuit, with printed components of microscopic size on a substrate, and typically including connections for a socket or wave soldering to a circuit board.. Brushing it lightly with a dryDefinition:
A signal with no added signal processing (e.g., no reverb or echo). toothbrush got rid of the hair, which fixed the problem. But simple corrosion can also happen between pins and sockets, including ribbon connectors. With ICs, insert the blade of a small, thin screwdriver under the bottom of an IC (usually one of the ends hangs over the socket a little bit), preferably between the IC and its socket. Push the IC up about 1/16”—just enough to raise it slightly out of the socket (Fig. 3), then push it back down again into the socket.
If possible, do the same thing on the other end of the IC. Raising and re-seating the IC wipes the connection between the pin and socket, which reduces corrosion.
The same technique can also work with ribbon and Molex-type connectors; with these, I usually lift the connector completely out of the socket and then plug it back into place. Some connectors have lips or retainers that prevent pulling the connector off, so you may need to push or pull on the retainer to free the connector. However, be very careful with the paper-thin, flexible kind of ribbon connectors that are held against circuit boards with plastic retainers. These are rarely the problem and are best left alone unless you really know what you’re doing.
5. Membrane Keyboard Fixes
Many membrane keyboard designs are based on conductive plastic that sits above the traces on a circuit boardDefinition:
A flat, thin piece of material, usually made of epoxy-glass or phenolic, on which various components mount. Thin electrical pathways called traces, usually made of copper, provide the electrical connections among the various components.. Pushing down on the plastic completes the connection, but if the plastic or circuit board traceDefinition:
See Circuit Board. becomes dirty, the contact can become intermittent.
Sometimes it’s possible to take the unit apart to where you have access to the conductive plastic switches, for example, by unscrewing the circuit board with the traces that sit underneath the switches. Soak a cotton swab in 90% isopropyl alcohol, and use it to clean off the bottom of the conductive plastic (Fig. 4). Also, swab the traces on the circuit board that the switches contact.
And by the way, you may hear of people who scrape the circuit board traces lightly to clean it. Don’t! Those traces are thin, and even a little scraping can cause permanent damage. Also, if the problem is crud on the plastic switches, scraping the circuit board won’t help.
6. Bad Electrolytic Capacitors
This gets more difficult, because it may require soldering skills, and more disassembly than you’d like—but electrolytic capacitors can age, and eventually fail. In some cases, this isn’t visually apparent, so unless you know how to test capacitors in-circuit, you won’t be able to do a fix. However, sometimes there are visual cues, like a capacitorDefinition:
An electronic 2-terminal component that can store electricity. It consists of two conductors separated by a very thin insulator (called a dielectric). that’s swelled out, or possibly even one that looks singed or burned. Replace the capacitor with a similar value.
If the capacitor has burned, you may not be able to read its value. But look closely at the circuit board—the value may be printed on the component side.
7. Intermittent Controls and Switches
We all know that when a volume control sounds scratchy, a little contact cleaner can clean up the sound (unless the problem is a leaky ACDefinition:
(Alternating Current): Current whose electrical flow alternates between positive and negative quadrants, and whose magnitude varies periodically. Alternating current is used in most commercial power transmission, and is also the basis of audio or video signals. blocking capacitor that passes DC—no contact cleaner can fix that, so you need to replace the capacitor). But if a control doesn’t pass audio, then we don’t have an audible indication that something is dirty. So if a control or switch seems intermittent, before thinking you need to replace the component, first try some contact cleaner. Note that conductive plastic faders require a different type of contact cleaner, and there are also cleaners optimized for gold contacts. The Caig Labs SKAV35 Audio/Video DeoxIT Survival Kit is well worth having around, because it includes all of Caig’s essential contact cleaning products, including wipes. And no, I don’t get a cut from Caig for mentioning their products—but when one of their sprays fixes a problem, I get gratitude from readers!
