Get the Most from Your Guitar Tech by “Speaking Repairman”
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| Gary Brawer |
LAST ISSUE WE talked about mechanical
buzzing. This time
around we’ll list some
tips for troubleshooting
unwanted electrical
noises.
Almost daily, I am
asked to diagnose electrical
hum, buzz, or
crackle. The first thing
I do is narrow it down.
Is it the pickups, or is
it the wiring/shielding?
Here is an easy way to
tell: Touch any metal
where you plug in the
guitar (output jack or
metal jack plate). If the
buzz goes away, it usually
means your guitar is
in need of a good shielding—
which is typically
done with shielding paint
or copper foil. Keep in
mind, you should be able
to touch the strings and
have the same effect. If
you touch your strings
and the noise gets louder,
there is a good chance
your strings are not
grounded (or they are
coated, as some coated
strings do not ground
quite as well.) Just by
grounding your strings
you can bring down the
hum. This is accomplished
by grounding a
bridge stud, a spring claw,
or a trapeze tailpiece.
If you’re touching the
strings or metal and you
still have hum, I’m betting
you have single-coil
pickups. We all know
that single-coil pickups
have a different kind of
hum that will not go
away unless “bucked” by
another coil. (Get it?) In
the past, Fender, Music
Man, and others have
tried hiding a dummy
coil on the guitar to
cancel the hum. Most
pickup manufacturers
now make hum-cancelling
versions of your favorite single-coils, and
these pickups sound
better than ever. There
are some new inventions
in the search for
the hum-free single-coil
sound. Ilitch Chiliachki
came up with a unique
product, which is also
sold by John Suhr. He
has embedded a coil into
a Stratocaster backplate,
a P-90 control cover, and
a Telecaster pickguard
to act as a hum-cancelling
coil to your existing
pickups. The system
is tunable and, when set up correctly, has
a very small effect on
your sound and allows
you to keep your stock
pickups.
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| Two methods of shielding: The left side is copper tape, the right side is shielding paint. They both get the job done. I solder the seams of the copper and hardwire it to ground to assure a solid connection. To ground the conductive paint, I have a piece of copper tape under the paint that’s wired to ground. |
Other potential
sources of noise are
your guitar’s volume
and tone pots and output
jack. Here’s an important
tip for tightening
loose, crackly potentiometers:
To keep the
pot from spinning and
breaking off all the
wires inside, be sure
to turn the post to the
full counter-clockwise position and hold it in
place while you tighten
the nut. Likewise, for the
output jack you can use
a flathead screwdriver to
keep the loose jack from
spinning while tightening
the nut. If your output
jack is staticky, roll some
fine sandpaper up like a
cigarette, and sand out
the corrosion from the
inside of the jack.
If you hear crackling
when turning a volume or
tone control, try cleaning
them. Places like Radio
Shack sell potentiometer
cleaner/lube. Be sure it
says “Safe for Plastics”
so you don’t melt your
pickguard or mess up
your guitar’s finish. A
small squirt in the pot,
and then twisting the
knob back and forth
to work it in will most
often do the trick. If you
have a hollowbody guitar
and can’t access the pot,
Stewart-MacDonald sells
a pot cleaning cap—a cool
attachment that screws
to the top of the pot and
forces cleaner down from
the top.
Hopefully these tips
and tricks can give you a
better understanding of
these problems and how
to discuss and remedy
them.