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Tech:
Troubleshooting Tips
There’s no getting around Murphy’s Law, but here’s how to
avoid paying dearly.
You remember Murphy. That pessimistic fellow who once said
“…anything that can go wrong will.” Sometimes he’s all too
right—like when a gremlin gets in your system and says
“gotcha” right when the crowd is singing “The Bride Cuts The
Cake.” How do you avoid being a victim? Here are some
troubleshooting tips to keep Murphy from wreaking havoc on your next
event.
TOOL TIME
A tool kit is a big help when things go awry. Include a pair of
needle-nose pliers, wire snips, a couple of screwdrivers, fuses,
vise grips, duct tape, electrical tape, and light bulbs for your
lighting system. I also recommend an electrical tester of some sort,
which you can get at any hardware store, so that before you plug
into that VFW outlet, you can make sure it is wired correctly! If
you know how to do continuity tests, then a continuity checker,
which checks for bad wires, is another good item for your tool box.
SPARE ME
Faulty wires and cables cause most problems. You should have at
least one backup cable for every type and style of cable in your
system. But sometimes things go wrong that you can’t fix on the
spot. This is why it’s so important to bring backup equipment. If
you use wireless, don’t leave home without a spare wired mic also.
If your disc player quits, a Sony Discman can save the show. A
Gemini PMX-7, for example, sounds great and fits in the bottom of
your toolbox, just in case your mixer goes on the blink.
If something big is going to fail on you during a show, it will most
likely be your amplifier. Your spare should be a professional, not
consumer model. It doesn’t have to be big, but it should be as
reliable as your main amp. Lightweight amplifiers, such as the MTX
P850 are an option. Soundtech has a couple of full-sized models that
will also fit the bill. For full main amp force, check out the PLX
series from QSC. Generally an amp even half the power of your main
will still be good enough to get you out of a bind.
TESTING 1, 2, 3
What do you do if a failure occurs? Start by working backwards from
your speakers to your sources (phono, CD player, etc.). Inspect the
cables, checking for frayed ends. If one speaker channel is dead or
humming, swap the cables. If the problem moves from one speaker to
the other, the speaker is good and the problem is elsewhere, or in
the speaker wire itself. Swap the cables at the amplifier. If sound
now comes out of the speaker that was previously dead then the
problem lies further up and not in the wire.
Next, check the amp to see if it’s getting a signal from the
mixer. Are the meters moving normally? If so, then you either have a
bad channel on the amp or a bad cable. Follow the same procedure as
with the speakers. You should shut off your amp every time you
change wires to avoid damaging pops and clicks. If you determine
that you have a signal from the mixer, and the wires are OK, the
problem is in the amp. If both channels are dead or humming, but the
meters on the amp are moving and you’re getting no sound, see if
the amp is in “protect” mode. Most models have built-in
protection from bad loads or short circuits. You could have a wire
that is shorting at the terminals or is frayed. If the two bare
wires touch together, that will shut down the amp.
If your mixer’s outputs are fine, check to see if the problem is
isolated to one source. If you have output on both channels from
everything but one unit, then the problem could be in the unit or
its wire. If so, break out the Sony Discman. If not, there is a
problem with the mixer.
With turntables you may have a loose connection in the tone-arm or
needle. Make sure the headshell is firmly seated in the tone-arm and
that the contacts are clean. If you are getting a nasty hum check
the turntable’s ground wires.
As for lighting systems, most of them are self-contained, so if you
have trouble with a unit, it will be out of commission with two
exceptions: the bulb and the fuse. Always spare fuses and bulbs for
each lamp you have in your system.
PREVENTATIVE MAINTENANCE
You can also use this procedure when checking your system before a
gig. Checking your wires in between gigs can reveal potential “hot
spots.” As far as your equipment is concerned, most of the
checking should be done with the system on, at low volume. Turn the
gains down on the amp for best results.
Being prepared ahead of time will definitely reduce your visits with
Murphy to a minimum.
System Failure
BE PREPARED! You should keep equipment backups (as well as other
essential items) on hand, ready to go should you have a problem. You
should also carry a toolbox that has screw and nut drivers, pliers,
cutters, jumper wires, plenty of audio adapters, fuses and light
bulbs.
For the average system you should have at least one backup cable for
every type of cable in your system. The most common system failures
can be traced to bad cables. You plug them in and out, you step on
them and run over them with your hand truck. Do yourself a big favor
and carry backup cables. If you use a wireless mic, keep a wired mic
handy as a spare. I find that a Sony Discman can be your best friend
when a CD player fails. Toss one in your toolbox (carefully) along
with a selection of premixed or compilation CDs just in case your
mixer should go down. As a backup, I suggest having a small mixer
available.
Now here is where things get a little bit more involvedx your
amplifier. Next to cables, the amplifier is the most common item to
fail. Never skimp on a spare amp either; get a professional model.
It doesn't have to be big, bad, and brawny, but it should be as
reliable as your main amp. Whatever you do, don't try to use a home
stereo system. They are not built for the heavy demands of pro
sound. A used, professional amplifier, even if it has half the power
of your main amp, will be good enough to get you out of a bind.
After all, a little music is better than no music.
Speakers are another matter when it comes to backups. Unless you
have a large van with room for a spare set of speakers, carrying a
second set around is probably not feasible. The best thing to do is
to protect your speakers from burning out in the first place by
using a compressor/limiter or speaker fuses.
If you have extra room in your car or van, you might want to carry a
spare tweeter or midrange, as these are the most common parts of the
speaker to burn out and are small enough to put under a car seat. If
you work alone and have a problemx BE COOL! Don't look at the
guests; look immediately at your system. Begin tracing where the
problem may be; it might be as simple as you hitting the wrong
button! Work as fast as you can to solve the problem. Then when
everything is running again, return to the festivities. Quickness is
of the utmost importance. Practice this at home with a friend. Have
him "cause" a problem on your system and you try to figure
it out. Pretty soon you will become familiar with potential problems
and, should it occur during a real live performance, you will
recognize it and solve the problem quickly.
If you've checked and determined it wasn't user error, you should
next check your cables. A typical sign of a bad cable is having a
channel suddenly drop out without the amp going into protect. You
may also get a hum or buzz in the system suddenly. Do a physical
inspection of the cables first. Make sure you have no frayed ends.
Then start tracing your way backwards. Start with the speakers; if
you have one channel dead or humming, swap the cables. If the
problem moves from one speaker to the other, the speaker is good and
the problem is further up, or in the speaker wire itself.
Next, swap the cables at the amplifier's output. If the problem
shifts between the speakers, then the problem lies further up the
chain and is not the wire. Move on to the amp. Make sure it is
getting a signal from the mixer. Are the meters moving like they
normally should? If so, then you have either a bad channel on the
amp, or a bad cable. Follow the same procedure for determining if
you have a bad cable to check your speakers. You should shut off
your amp every time you change wires to avoid any pops or clicks
from surging through your system. If you determine that you have
sound coming out of the mixer, and the wires are OK, the problem is
in the amp. It is time to break out your spare amp.
If your mixer's outputs are fine, check to see if the problem is
isolated to one source (CD player, turntable, etc.). If you have
sound coming out on both channels on everything but one unit, then
the problem could be in its connecting cable or the unit itself. If
so, break out the Sony Discman. If not, then there is a problem with
the mixer!
If you are using turntables, sometimes you may get a loose
connection in the tonearm or needle. Make sure the headshell is
firmly seated into the tonearm and that the contacts are clean.
Also, if you are getting a nasty hum out of the system, check the
turntable's ground wires.
Should your microphone go bad, and you don't have a spare, you can
effectively use your headphone as a mic. It will work fine, although
the sound will not be very good. Always keep a spare headphone in
your tool kit. Keep an assortment of Adapta-Plugs on hand as well.
This is a pretty straightforward approach should you have a problem
with one channel. If both channels are dead or humming, the first
place to look is the amp. Is it getting an output from the mixer?
You can determine this if the meters are moving and the amp is on,
but you get no sound. If so, then the problem could lie in the
amplifier. See if the amp is in its "protect" mode.
Many amplifiers have this built-in; it is designed to protect the
amplifiers from bad loads or short circuits. You could have a wire
that is shorting at the terminals or is frayed. If the two bare
wires touch together, that most likely will shut down the amp. The
best way to deal with problems on the job is to avoid them in the
first place. Don't try to use the same system you use for a
50-person backyard party as you would use for a 300-person high
school prom. These are totally different gigs which need totally
different systems. If you push your system beyond its limits, you
will damage it. Don't shout in your mic, and watch those clip lamps!
(Most amplifiers have an overload indicator called "clip."
If it lights, lower the volume!) And REMEMBER! Be prepared, and
don't panic!
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