Maintenance Techniques
ã 1998
by Eddie Ciletti


The secret to maintenance is not a degree in applied mathematics — all it takes is a new hat! Think I’m kidding? Hmmm, let’s see what the magic mirror has to say. I see Polly has her Musician’s Chapeau and Tom has an Engineer’s Cap… Of course there are many labeled head ornaments — Producer, Reducer, Babysitter and Cheese Head — but the hat you need to fix stuff says "Tech" on the front and "Made in USA" on the back.

But seriously, maintenance is a state of mind — creative in its own way. Audio gear may seem like complicated stuff but, as you will see, sometimes the solutions are quite simple. Always take a moment to re-read the manual, troubleshoot and document the problem, before contacting a technician. Don’t call without being prepared to answer several questions.


Two friends recently had problems with one channel of the main stereo mix buss: one was completely gone, the other distorted. (No jokes about my friends. Ok?) Both were ready to pay for a service call. As a favor, I attempted to troubleshoot the problem over the phone, being asked several times whether a broken wire, a capacitor or some other component might be to blame. Funny questions, I thought, because "even if," these were not serviceable items for either user.

The "Systems" approach to troubleshooting eliminates potential detours, one by one — from an external perspective — that is, without opening anything up. In case one — a Mackie 1604 — the "problem" was due to a compressor permanently patched to the stereo insert points. After moving the rack, one of the connectors leading to the compressor had pulled part of the way out. This is a good case for devising a method to relieve strain from cables.

In case two, an old D&R mixer, the immediate goal was to be online enough to do overdubs. Reseating all of the connectors on the rear of the master module didn’t do it. I had the user check the two-track return, making sure the problem was on the buss and not in the monitor chain. OK, so far. As a short-term solution, using any two of the eight "group" busses would do the job. Getting a tech on a weekend is not quite so easy, but at least the session was able to proceed.


Later, while writing this column, I thought about all of the external circumstances that might cause "signalis interruptus." Then it dawned on me: the mix buss showed up in three places on the bantam patch bay in order to feed three machines. Call number three began with the question, "had any gear been changed or removed?" Uh, yeah! The two-track analog machine had been pulled and the wires were left in a pile on the floor. One of the male XLR pins had shorted to ground. Need I say more?


That’s not to say that problems don’t originate inside the device, but before you throw money out the window, check all of the external connections first. Comparative analysis is your friend. Swap Left with Right at every step: Inputs, Inserts and Outputs. Try bypassing questionable hardware — especially insert points at the console that are not being used.

Plug a CD player into a pair of channels — assuming one is operational and the other, not. Plug a known working "insert" cable into the non-functioning channel, connecting the send and return together. If this does the trick, you’ve either got a tired jack-normal or a cold solder-joint. If not, try cross-dressing! Connect the insert-send from the "bad" channel to another’s "return." In addition, feed the insert-return from another module’s insert send. By doing so, you can check the input section of the modules separate from the output stage.


One way to keep on top of your gear is to have as much documentation as possible.  These daze, gear is out-of-date before it is shipped and quite often will require a software upgrade before you get started.  Fortunately, the Internet makes that easy as manufacturers realize its potential.


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