DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Dave Locher

New member
As the title says, I have a 1978 Randall head. It has two channels and came with a footswitch that allows one to switch between the two channels and to run both at the same time.

Unfortunately the switch unit is big and heavy, has a long, thick, stiff cord, and the plug connector is a bit iffy at best. The cable is thick and stiff because it has a lot of wires in it. In addition to switching the channels it also activates LEDs on the amp as well as in the switch. It is much more complex than I need.

How hard would it be to rig up a simple switch that would only do one thing: turn one channel on and off? I just want to be able to go from one channel to both. I don't need or care about the LEDs or the A/B option. I just want to channel A on all the time and a footswitch to turn B on and off.

I am handy enough to do this - I have rewired every guitar I ever owned, swapped dozens of pickups, modded effects, built my own cap switch box, wired my garage and the car I park in it, and rehoused this amp, etc. I just do not know how to figure out which wires I would need to connect to a switch to be able to turn one single channel on and off?

The file is too big to post here but the owner's manual actually has a wiring diagram for the head. You can see it here: Firmowe/RANDALL/randall%20rg100es-rg80es.pdf.html#schemat

Is this doable? I am not worried about harming the value of the amp but I am worried about killing it (or myself!). I have owned it since 1988 or so and don't plan to ever sell it.
 
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Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

As the title says, I have a 1978 Randall head. It has two channels and came with a footswitch that allows one to switch between the two channels and to run both at the same time.

Unfortunately the switch unit is big and heavy, has a long, thick, stiff cord, and the plug connector is a bit iffy at best. The cable is thick and stiff because it has a lot of wires in it. In addition to switching the channels it also activates LEDs on the amp as well as in the switch. It is much more complex than I need.

How hard would it be to rig up a simple switch that would only do one thing: turn one channel on and off? I just want to be able to go from one channel to both. I don't need or care about the LEDs or the A/B option. I just want to channel A on all the time and a footswitch to turn B on and off.

I am handy enough to do this - I have rewired every guitar I ever owned, swapped dozens of pickups, modded effects, built my own cap switch box, wired my garage and the car I park in it, and rehoused this amp, etc. I just do not know how to figure out which wires I would need to connect to a switch to be able to turn one single channel on and off?

The file is too big to post here but the owner's manual actually has a wiring diagram for the head. You can see it here: Firmowe/RANDALL/randall%20rg100es-rg80es.pdf.html#schemat

Is this doable? I am not worried about harming the value of the amp but I am worried about killing it (or myself!). I have owned it since 1988 or so and don't plan to ever sell it.

The link needs fixing first.
 
Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

I had a Randall combo with a foot switch with a thick gray cable and a special nonstandard 6-pin plug to the amp that ran the channels and LEDs. When it died I never found a replacement or a way of fixing it.
 
Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

I had a Randall combo with a foot switch with a thick gray cable and a special nonstandard 6-pin plug to the amp that ran the channels and LEDs. When it died I never found a replacement or a way of fixing it.

That is the footswitch I have! Weighs a ton, takes up more room than the head because of the looong stiff cable, and the plug is finicky about making good contact and pulls out easily. I literally used it on stage one time.
I am hoping there is a simple way to splice into one or two of the wires and make a simple on/off switch for the green channel. I don't need led lights to tell me when it's on or off.
 
Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Have you opened the footswitch to see what that's like?
 
Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?


Umm !
Nie znaleziono

Szukany plik lub folder nie istnieje

maybe this one will.
- http://www.guitarelectric.eu/pict/Firmowe/RANDALL/randall rg100es-rg80es.pdf -

It has the switch wiring in it. I haven't studied it closely yet but it looks like you you could hack a single channel switch.
 
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Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

You could always contact someone like ampfootswitch dot com and see if they can make what you want.
 
Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Sorry, GV. That was the one I was trying to link to.
I did open up my footswitch once years ago. All I saw was two standard footswitches and about a dozen small wires.
I am positive I can splice two of the wires to a jack and make a simple switch, but I don't know how to figure out which wires I would need to connect to the switch.
 
Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

You could always contact someone like ampfootswitch dot com and see if they can make what you want.

I thought you were joking! I can't believe there is a site just for amp footswitches. But I plan to DIY this anyway. Cheaper and more fun.
 
Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Okay, I just found this thread: http://music-electronics-forum.com/t41970/

They seem to suggesting that the switch functions by grounding the preamp signal to ground, like a kill switch in a guitar. Is that correct?
If so, does that mean I can just short to ground each of the 6 wires one at a time until I figure out which one kills Channel 1 when grounded?

OR would that risk frying my amp?
 
Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Okay, I just found this thread: http://music-electronics-forum.com/t41970/

They seem to suggesting that the switch functions by grounding the preamp signal to ground, like a kill switch in a guitar. Is that correct?
If so, does that mean I can just short to ground each of the 6 wires one at a time until I figure out which one kills Channel 1 when grounded?

OR would that risk frying my amp?

If you read the whole thread , they suggest there's variations on the circuit and there's a switching chip in some of them. It still seems the basic concept of grounding the "selector " wire is present . If you have a multi meter, measure each pin for voltage.

It looks like pin 2 and 6 are your amp wires. Pin 3 and 4 are common / ground.
[ if your feeling adventurous, touch a screwdriver between pin 2 and 4 or 6 and 4 and see if it switches. If it does it will probably just mute the channel. If you want to be safe, use an LED to connect the pins. ]
38819d1461637934-fs5schem.gif
 
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Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Yeah, I read through the whole thread but my amp is a 1978, so I am sure it has the oldest/simplest switching circuit.

Thank you. I will give that a try and report back.
 
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Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

Re: DIY Hack footswitch to just turn one channel on & off on my '78 Randall RG100ES?

It works! Connecting 2 and 4 with a jumper wire does in fact silence channel 1, which is what I wanted.

So now my plan is to move those two wires over to the never-used reverb on/off jack right next to the 6-pin plug and just use a cheap, simple footswitch to turn it on and off.
THANK YOU!
 
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