STOMP SCHOOL
ANALOG TOM with ANALOG MIKE
Troubleshooting & Maintenance 101, Part 3
Hey pedal-heads, welcome back to Stomp is often caused by a loose connection in
School. This month, we’ll wrap up our the pedal—in one of the jacks, wires or the
troubleshooting and maintenance series with switch. It can also be caused by a very sick
some more advanced tips for solving your component (transistor, e.g.).
pedal problems. In part one of our troubleshooting discussion, we suggested taking a
noisy or troublesome pedal out of your rig
to deal with it later. Now we’re going to deal
with it.
Many problems, especially on older pedals,
are caused by poor solder joints. This problem may be getting worse, as most builders
are being forced to use lead-free solder for
European RoHS. If you can wiggle a wire
or component, and the lead moves on the
attachment point, the joint is very bad and
needs to be redone. The best repair is to
de-solder it and redo it with fresh solder. If
you don’t have de-soldering tools, touching
it up with a little new solder usually does
the trick. (There’s a great tutorial called
“how and why to solder correctly” on
You Tube.) Often the solder joint is not
physically loose but will be dull and
chalky—another sign of a bad joint.
Intermittent sound, and noise caused
by poor solder joints, can often be
exposed by gently twisting the circuit
board. If twisting the board cuts the
signal on and off, there is probably a
bad joint somewhere.
If the pedal is passing signal and works
properly, but seems unusually noisy, there
are a number of things that could
be causing the problem. First, check
the power supply. Using the wrong
power supply can cause noise and
hum, and can damage your pedal.
A generic power supply like you
find at Radio Shack should never
be used with pedals. You need one
designed for effects, one that is
both regulated (voltage does not
drift) and filtered (no noise from the
AC line). If the pedal runs at 9 volts,
try testing it with a battery.
White noise, a sort of a hissing sound, is
another common type. Most pedals will have
some, but excessive white noise could be
due to some bad electronic components or
a need for calibration. The last common type
of noise is a high-pitched squealing sound.
This can be caused by feedback oscillations
After you’ve confirmed the power
supply as the cause, you can look
at the pedal itself. When testing a pedal for
noise, set the volume knob for unity gain (the
volume is the same whether the pedal is on
or off). Turning the volume up will amplify
any noise that’s already there, making it more
apparent. If you turn your guitar volume all
the way down, you can hear what’s actually
coming from the pedal. A slight white noise
is normal on many pedals when set at unity
gain. If you are hearing excessive noise from
your pedal when it’s not boosting your signal, try to determine what sort of noise it is.
in the pedal due to poor wiring layout—wires
should not be in neat parallel lines, like those
found in some boutique pedals. In analog
delay pedals and others with BBD chips (
chorus, flangers, etc), squealing can be caused
by poor calibration.
Open up the pedal while it’s still plugged
into the guitar and amp, leaving the volume
on the guitar all the way down. Probe the
inside of the pedal with some non-conduc-tive device to see if you can locate the
source of the noise. It could be a bad solder
joint, failing switch contact, faulty connections with a jack or pot, or it could be a
faulty component on the board. Try wiggling the battery clip to see if that causes
any noise. You can also try to re-route the
wires to stop some noises, like whistling.
Unfortunately with most mass-produced
pedals made these days, there is nothing you can really do inside: everything is
directly soldered to the board, no hand
wiring, and using proprietary parts that
can’t be replaced. When one of these pedals dies past the warranty, you’re probably
holding a paperweight.
Noise is relative, so you may want to
compare your noisy pedal to a similar
one (there’s a reason some people call
them noise toys). If there is definitely a
problem but you just can’t figure it out,
it’s time for professional help. If the warranty
is still valid, that’s your best bet. Otherwise,
see if you can find a qualified local repairman to bring it to. Often the problem will
disappear when your effect is tested by a
tech, like about half of all pedals we get in
for repairs. Maybe they just like getting out
of the house.
Check back with us next month. Until then,
keep on stompin’!
Humming noise is a low frequency, consistent hum, like you hear when playing a guitar with single coil pickups near electronics.
This usually comes from AC power leaking
into your signal somewhere, or it could be
your guitar pickups. Try a guitar with humbucking pickups to make sure the noise
is actually coming from the pedal and not
the guitar. Hum can also come from a bad
ground, like the sound you hear when you
pull the cord out of your guitar.
Static noise is an inconsistent crackling, like a
bad cable or guitar jack would make, which
Tom Hughes
(a.k.a. Analog Tom) is the owner and proprietor of For
Musicians Only ( formusiciansonly.com) and author of
Analog Man’s Guide To Vintage Effects. For Musicians
Only is also the home of the FMO Gear Shop.
Questions or comments about this article can be sent
to: stompschool@formusiciansonly.com.
Analog Man
( analogman.com) is one of the largest boutique effects
manufacturers and retailers in the business, established by “Analog” Mike Piera in 1993. Mike can be
reached at AnalogMike@aol.com.
