ASK SKIP
WE'D LOVE TO HAVE THAT PROBLEM... Skip Simmons
Skip, my Blues Junior’s RCA plugs before the amp will work well. Next is
going into the reverb tank have a the fact that older electrolytic capacitors
loose connection. Moving the amp or used in vintage amps are in some ways
vibrations cuts the reverb out. It can very similar to a battery. Remember
be jiggled until it makes connection opening up a flashlight and finding that
again. How can I tighten the jack to the batteries had basically disintegrated?
make a solid connection? I’ve tried Electrolytic capacitors can do the same
pushing on the outer sleeve, but no thing. Regular use certainly seems to
help there! ~ Robert extend their life and I have personally
seen hundreds of ancient caps that were
Great
question
Robert!
Those
still hanging in there, especially in Fender
innocent looking cables that are used
and Marshall amps.
on both new and vintage amps to
connect the amp chassis with the Is there anything else you can do to help
reverb tank are a common source of your collection? Yes, there is. Unless your
noise, weak or non-existent reverb, ohms and the output coil will read around 170 amp uses a slow warm-up rectifier like a
and intermittent issues that can affect the amp ohms. If your meter reads open, you’ve found 5AR4/GZ-34, the electrolytic filter capacitors in
even when you aren’t using the reverb. You the problem. Inspect the wires carefully. If you the power supply will have a very high voltage
already know that keeping the RCA plugs clean find a break, you should be able to repair it applied to them within a second or two of
and tight is the first step, but it sounds like you by re-soldering. powering up. Just like trickle-charging a dead
may have an intermittent break in the actual wire
battery, it is a better idea to apply voltage
itself. This wire is shielded. It consists of a very
gradually if you want to extend the life of the
fine inner conductor (the “hot”) and a wire shield Skip, I have 15 vintage low watt amps that I capacitor. The easy way to do it is with a variac,
(the “ground”). If either conductor develops a love, but with that many some don’t get played which is a cool-looking gizmo with a big knob
short or a break, you will have reverb problems. but a few times a year. Is it true that in this on it. Plug the variac into your wall socket
case it’s beneficial to just turn them on without and then plug your amp into the outlet on the
Try replacing the cables first. Since DVD players plugging in and let them run idle for an hour variac. Make sure the power switch of the amp
often use the same type of cable, they are easy or so every so often, and that will prevent the is “on” and that the standby switch (if any) is
to find. If you still have problems, there may be problems that can happen to tube amps that in the “play” mode. When that big knob is off,
an issue with the RCA jack that is mounted on just sit unused? ~ Steve your amp is off, but turning it raises your AC
the amp chassis (which would require a visit
wall voltage from zero to 120VAC at any rate
with your tech to rectify) or a problem with the Hello Steve, thanks for writing. Wow! 15 vintage that you choose. When I’m making an effort to
jack on the reverb tank. This is something you amps? I bet a lot of CG readers would love to preserve old caps, I like to turn the variac to
can investigate yourself. have your problem! 30 volts for half an hour, then go up about 20
volts every 10 minutes or so, but even if you
An ohmmeter is very useful when trouble- Basically, the answer is yes. A good old amp take just 90 seconds to go from zero to full wall
shooting reverb problems. Inside the reverb can easily fire up every day for ten years with voltage, you are really helping to preserve those
tank are two small coils located at each end zero problems, but if you turn it on after it has old parts.
of the springs. There are two flexible leads per been sitting for ten years, you can expect some coil that connect to the “input” and “output” issues. If an amp sits unused for long enough, Since I love old stuff I use a vintage variac,
jacks mounted on the exterior of the reverb a couple of things can happen. First is oxidation but current-production imported versions are
tank. Using the ohmmeter, measure the of movable contacts in the amp, which is available as well for $100-150. A unit rated at
resistance between each pair of wires. On all a fancy way of saying that you may need to 5 amperes will be sufficient for everything but
Fender amps, the input coil will read around 2 clean the tube sockets and potentiometers your SVT or Marshall Major.
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Mar Apr 2017
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