Fender Twin Reverb/"custom" Vibrolux Reverb foot switch noise

[mrkgtr49]

I have one each of these two amps, each having a two button foot switch for reverb and vibrato on/off. Both use a Switchcraft 238x plug and three conductor cable to connect to the amps. They are interchangeable. One is marked "Made in Mexico", the other isn't. The one marked "Made in Mexico", when plugged into an amp, makes a static-y, crackling noise when touched or moved. The other one is completely silent. On the noisy one I have replaced the Switchcraft plug, soldering it very neatly and identically as it was, also comparing it to the other switch. I've checked both switch assys' with a meter, and both work as they should; no shorts or opens where there shouldn't be. Inside the switch assy's both are wired identically, and there are no stray strands of wire sticking out of any of the conductors to contact ground. One of the conductor wires has the "common" wire braid around it, and it reads good continuity through it. This braid is soldered to the metal plug housing at one end, and goes to one terminal of each switch at the other end. Visually and meter-test wise, both foot switches are identical.
I am totally at a loss to understand what's going on. It almost seems that the actual cable is bad inside, but I've never heard of foot switch cable being bad like this! Usually, if a conductor is broken inside the sheath, that circuit won't work.
Has anyone ever seen this situation before?

Thanks!

[soundguruman]

It's just a noisy switch, the contacts are worn.

[mrkgtr49]

I just reread my post and realized that I neglected to mention that it's the CABLE that makes noise when moved. My bad! The switches operate pretty normally...they turn the functions on and off correctly, but the slightest touch on the cable makes a static sound; almost a microphonic noise like a microphonic tube or guitar pickup. If I tap on the cable, I hear a tap thru the speaker. If I bend the cable back and forth, it sounds like someone crinkling a candy wrapper next to a mic. Weird.
Sorry about the confusion.

[52 Bill]

I just reread my post and realized that I neglected to mention that it's the CABLE that makes noise when moved. My bad! The switches operate pretty normally...they turn the functions on and off correctly, but the slightest touch on the cable makes a static sound; almost a microphonic noise like a microphonic tube or guitar pickup. If I tap on the cable, I hear a tap thru the speaker. If I bend the cable back and forth, it sounds like someone crinkling a candy wrapper next to a mic. Weird.
Sorry about the confusion.

Remember that the reverb part of the cable is carrying audio, the reverb return signal. If the cable becomes microphonic due to capacitance, it will make the kind of noise that you describe. Turn off the reverb, does the cable noise still come through the speaker?

[Enzo]

If you have two otherwise identical footswitches, and one has a noisy cable and the other does not, then accept that the one has a bad cable and rewire it.


Cables can be microphonic or otherwise mechanically sensitive. The looser their construction, the more likely that will happen. Also, cables that have been walked on enough will start to have breaks in the shielding weave or wrap. The wire as a whole will still have plenty of continuity, but broken ends of strands touch and untouch and that makes crackles and pops.

[mrkgtr49]

Thanks for all the info, folks! When I switch off the reverb, the noise goes away. Nice call, 52 Bill. I pulled the bottom off the switch housing and found some broken strands of shield wire. I'm going to tin the exposed shield at the switch and the plug ends. Assuming that won't cure the problem, does anyone have any idea where I might find replacement cable of this type? I've never seen it before.

Thanks!!

[soundguruman]

Thanks for all the info, folks! When I switch off the reverb, the noise goes away. Nice call, 52 Bill. I pulled the bottom off the switch housing and found some broken strands of shield wire. I'm going to tin the exposed shield at the switch and the plug ends. Assuming that won't cure the problem, does anyone have any idea where I might find replacement cable of this type? I've never seen it before.

Thanks!!

Mojo Wire » Fender Double and Single Footswitch Wire

It does go bad, but not often

[mrkgtr49]

The tinning didn't really help, so it's gonna be new wire. Thanks for the link soundguruman!!

[g1]

Those cables are 12ft. long? For $25 worth of cable is it worth fixing? I didn't think the whole assy. was all that much more money, might be worth replacing and saving the old for parts?

[mrkgtr49]

Yeah, but new ones are $45-50.00 anywhere I've checked. I don't mind fixing this one (like most musicians I have more time than money), and I don't need to do it right away; I've got two at the moment. Besides; if these things go bad now and then, I don't want to buy a used one that might get noisy a month after I buy it.
Thanks for the suggestion, though.

[g1]

Well, if time isn't an issue, it may be worth cutting the cable back a few inches & rewiring at both ends. You might get lucky.

[soundguruman]

Well, if time isn't an issue, it may be worth cutting the cable back a few inches & rewiring at both ends. You might get lucky.

It's oxygen that takes a toll on the wire, so polish the wire with scotch bright before you try to solder it.
try to get all the old crud off the outside of the wire first, shine up the metal before soldering
but it does actually decay to the point of no return, to where it's almost rotted, eventually
when you live near the ocean or where it rains a lot, in a humid climate this speeds up the process

[mrkgtr49]

This particular foot switch came with a used "Custom" Vibrolux Reverb that I bought used in Scottsbluff Nebraska. Someone had already done a hashed repair at the plug end, and I knew it wasn't working because of that botched repair. I let it sit for almost a year before I decided to fix it correctly. Now I'm thinking that the reason someone attacked the plug connections was because of the crackling noise. The cable is already about six inches short of twelve feet, so they probably cut it hoping to eliminate the noise.
I think it best to start with new wire. I'm going to do the "Mark Moyer Mods" to the amp, and it will be nice to have a functioning switch unit to use with it, and not have to swipe one from the Twin when I want it.

[imaradiostar]

You might find that any generic cable intended for microphone (balanced) use will work. It's likely to be cheaper!

Or it might be too noisy!

Jamie

[mrkgtr49]

I though about mic cable, but the shield is wrapped around both conductors, and in the foot switch it's just around one of them; I presume to keep the vibrato switch's "pop" from getting into the reverb return. I'm still shopping for a dual shielded cable that has shields around both conductors, and that's small enough in outside diameter to fit through the hole in the pedal. It would be nice if it were also more flexible than the Fender cable!