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Footswitch Wiring - RD & RP Series


Steve Kennedy
Posted on Sunday, June 02, 2002 - 04:08 pm:   

I don't yet have a drawing of the RD/RP footswitch prepared. However, here is a verbal description of the wiring:

There are 5 components inside the footswitch body itself:

Distortion switch (ON/OFF SPST, two contacts)
Reverb switch (ON/OFF SPST, two contacts)
.1uF, 100V disc ceramic capacitor
3 contact terminal strip (A, B & C)

Each of the cables:

Distortion (or Phasor)

have a center conductor (Hot lead) and an outer Shield connection.

Distortion Cable connections: ---------------------------------------- ---------------------------------------- -------------

The Shield connects to the Distortion switch (either contact). The other side of the switch connects to the Terminal strip at "A". The Hot lead connects to the Terminal Strip at "C".

Reverb Cable Connections: ---------------------------------------- ---------------------------------------- ----------------

The Hot lead connects to the Reverb switch (either contact). The Shield connects to the other side of the switch AND to the Terminal strip at "B".

LED: ---------------------------------------- ---------------------------------------- ---------------------------------------- ----

The Cathode (shorter lead on the side with the flat area on the body) connects to the Terminal Strip at "A". The Anode (longer lead) connects to the Terminal Strip at "C".

.1uF, 100V Capacitor:------------------------------ ---------------------------------------- ----------------------------------

The capacitor connects between the Terminal Strip contacts "A" and "B".

Terminal Strip: ---------------------------------------- ---------------------------------------- --------------------------------

Connects as indicated in all the above steps, but also includes a connection to the metal body of the footswitch at "B".

You should be able to draw a diagram from the above steps and create a working Music Man RD or RP footswitch.


Dirk Wacker (doc_holiday)
Username: doc_holiday

Registered: 02-2007
Posted on Tuesday, February 13, 2007 - 10:42 am:   

Hi, I tried to make a drawing out of Steve?s description. Please have a look here: here - can anyone verify that the drawing is correctly ?
Edward Solberg (edward_solberg)
Username: edward_solberg

Registered: 05-2006
Posted on Sunday, May 13, 2007 - 08:07 am:   

your drawing is fine.
Paul Thomas (tallpaul)
Username: tallpaul

Registered: 11-2010
Posted on Saturday, November 27, 2010 - 08:51 pm:   

Thanks for your info does any one know where I can buy this cap in aus, will mylar do? My fender moc up is looking good with a coat of paint, just need to find a picture to copy so I can make a sticker for the top. Cheers.
Jay Hammond (jead)
Username: jead

Registered: 01-2011
Posted on Monday, March 07, 2011 - 10:20 am:   

I have an RD footswitch I'm trying to operat a 2475-65 (Rev/Trem) with. Wired exactly as the diagram. The Rev switch does activate the reverb, the distortion switch does nothing for the trem. Seems to me it should. Of course the led does not work with this amp and I didn't expect it to since the internal stuff in tha amp isn't there. Do I need to wire the distortion switch differently to get the tremolo working?
Jay Hammond (jead)
Username: jead

Registered: 01-2011
Posted on Sunday, March 13, 2011 - 10:09 am:   

Anyone? Ideas?
Jay Hammond (jead)
Username: jead

Registered: 01-2011
Posted on Sunday, March 13, 2011 - 02:24 pm:   

Ok - For some reason the distortion switch I want to use to activate the trem is SPDT. Should I just swich it out to a SPST switch and expect it to work? Thanks
Lars Verholt (lmv)
Username: lmv

Registered: 11-2009
Posted on Sunday, March 13, 2011 - 05:27 pm:   

Hi Jay,

a SPDT will work in place of a SPST switch - you just use one side of it. The tremolo in the older amps is switched on when the connection is 'open' and off when the connection is closed. If you use an RD series foot switch, the distortion button will give tremolo 'on' when the switch is open - i.e. it works opposite what it would in its original (RD) hookup. Clear as mud?

Try swapping the two RCA plugs - the reverb button should now control the tremolo on and off. Does the tremolo work with no foot switch hooked to the jack?

Lars Verholt
Jay Hammond (jead)
Username: jead

Registered: 01-2011
Posted on Sunday, March 13, 2011 - 05:43 pm:   

Thanks Lars - The tremolo works fine without the switch. It didn't work at all with either side of the RCA plugs when I still had it wired up. Still wired, only the reverb SPST worked. I've taken the SPDT out and now the remaining SPST works either trem or reverb. That just seems odd to me. I'm guessing at this point that the SPDT switch must be bad. I'm going to wire it back in and confirm everything again. I'll post back shortly with results.
Jay Hammond (jead)
Username: jead

Registered: 01-2011
Posted on Sunday, March 13, 2011 - 06:00 pm:   

Ok - re-wired. The red RCA plug is wired to the SPST and the black to SPDT. The red plug will operate either trem or reverb. The black does neither. I do get continuity readings from the black side wire so I have to think the switch is bad. Would you agree?
Lars Verholt (lmv)
Username: lmv

Registered: 11-2009
Posted on Sunday, March 13, 2011 - 06:29 pm:   

Well - do you get continuity reading if you measure directly on the switch? Don't assume that the black wire is good just because it looks good. As I'm sure other forum members can attest to, the angle RCA jacks and at times the co-ax wires can be troublesome and go 'open'.

PS - the tremolo control wire needs to be shielded as not to pick up noise. I learned the hard way and brought the wrong kind of cable with me to a gig.

-Lars Verholt
Jay Hammond (jead)
Username: jead

Registered: 01-2011
Posted on Sunday, March 13, 2011 - 07:51 pm:   

I get readings from the switch and weaker readings off the wire. I believe the cord is original and I've inspected it a few times for cuts and nicks - it looks good. I have some switches in a Vox box that I know are working on tha amp so maybe tomorrow I'll wire one of them in and see whats what. If it doesn't work with a switch I know is good it has to be the co-ax. I assume the .1uF cap has no bearing on this. Thanks Lars.
Jay Hammond (jead)
Username: jead

Registered: 01-2011
Posted on Tuesday, March 15, 2011 - 02:41 pm:   

It's fixed. All I did was wire the distortion side exactly as the reverb side. I left the jumper from the switch to the A terminal disconnected. So the hot on the distortion side now goes to the switch instead of the C terminal. The hot I believe was powering the LED in the diagram.
MidCenturyAudio's picture

100 RD foot switch "pop"s when switching back to main channel

Restoring a RD-100 and was having trouble finding a real RD foot switch - but I had a spare tremolo/reverb version and decided to build my own RD version using the circuit described at the head of this post. I drilled a hole, added the LED and re-wired the whole thing. It works with switching both and the LED works as well, but when it switches back from the second channel there is an audible pop - which at low volumes is ok but when it's cranked it's very loud as well. Any suggestions? Maybe increase the cap value?



I had a similar problem with my RD65. The cause was a cold/loose solder joint at C44 .1uF cap. to ground. It's job is to absorb the voltage spike from the foot switch/LED On/Off event. It had gotten bent over while I was doing other work on the PC board and the stress broke the weak solder joint. C44 connects to D19 and IC-6 input. It's to the right of the the footswitch/LED on the schematic. This is the circuit that controls the Clean/Dirty CMOS switches. Good Luck. -mgriffin

Dubby Dub Dub

Has anyone got a wiring

Has anyone got a wiring diagram for this footswitch? I tried using the footswitch off a sixtyfive reverb which didn't work!


See Schematic

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