I used to have a Peavey Classic 30 that had switchable distortion and reverb. However the included footcontroller lacked LED indicators to tell if the dist/reverb was on or off. There are LED-equipped footswitches on the market, and I even believe Peavey’s newer versions have LEDs.
Well, why spend money on a new switch when you could simply get into DIY-mode?
The circuit used here isn’t guaranteed to work on all amps, but if the amps uses relays for the switching, chances are this should work on other amps as well. Be sure to check polarity on the footswitch jacks.
The Peavey switch connects to the amp via a cable with two wires + what appears to be a common ground in it. However, the naked wire is actually the positive supply, and the two other wires supply current to the relays for distorion and reverb. Roughly like this:
So it’s really just two spst (1xon/off) switches that turn on the current to the relay coils. The key word here is current. The coils need a certain current to achieve a sufficient magnetic field an thus be able to move the mechanical switch in the relay.
Now, as I actually don’t own the amp anymore, I’m not that sure about the numbers here, but I measured the voltage from +V to coil with switch open, and I think it was around +30V. The more important thing however is the current, the currents were sligthly different for the two relays, but both were somewhere around 20-25 mA. I’m not sure how much the relays need, but this is important as the leds used were rated at max 30 mA, and now there’s no need to add series current-limiting resistors.
I opened the switch by removing the bottom plate. It wasn’t glued or anything, so a sufficient amount of brute force worked fine. The only thing I needed to do was to add LEDs in series with the switches. Like this:
The naked conductors need some sort isolation of course, normal electrical tape works fine.
Done!
As I sold the amp after finishing the mod, I never got to test it on a gig. But it worked just fine at home, and as long as the LEDs don’t fail, I’m sure it will go on working fine. (if a LED fails there will be problems, as they are in series with switches. But not harder to fix than replacing the LED, they are really cheap)
Update: part layout and schematic picture:
What's wrong with this circuit? 
Hi,
I always wanted to modify my footswitch. Finaly, i found. Never thought that it was simple as that. Although, I have a question. Do you remember the specs of the leds ? I’ve done some search and there are many with different specifications.
Thanks !
David
Hello! The leds are very basic, not “ultra-bright”. The forward voltage is somewhere between 2,1-2,3 volts (can’t remember exactly) and the maximum current is 30 mA. The choice of led shouldn’t be that critical in this application, the max current is the most important thing to keep in mind.
Thanks for your fast answer. I just came back from the electronic store. I took your message aster I just bought them, but I think I bought the right thing. I am about to install them today.
Thanks again.
PS: I was wondering why you didn’t put your leds on the top instead of the place you’ve put them? If you see inside, there is already a hole for an additional switch and 4 smaller holes that the 5mm fits perfectly. Two of them are right beside the switch and also let you have your wires of both switch far from each other so no shielding with a tape or shrink cable has to be made.
I simply liked the way it looked having them there. 😃
I just finish the mods and it doesn’t work. The reverb and amp switches stay off and no leds. Done something wrong? I have a multi meter but doesn’t really know how to work with it. Can you guide me through that? Maybe it’s the leds values that doesn’t fits.
There is a slight chance that Peavey has altered some parts of the circuit, my amp was bought in 2004, so I can’t guarantee that the same solution works on new amps. But try the following:
-Connect the footswitch to the amp, make sure the channel button is in it’s down position on the amp.
-Inside the footswitch, disconnect all leads. Measure the voltage between the grey wire and the black. Should be around 30 Volts. Make sure that the polarity is right, the ground och your multimeter should connect to the black wire. Do the same measurement between grey and red.
-If all the voltages seem ok, check the currents. Connect your multimeter (in current mode) between grey and black. The Reverb should now turn on (make sure the reverb pot on the amp isn’t at zero!). The current should be somewhere around 20-30 mA. Do the same measurement between grey and red. The drive channel should now turn on. Check current again. If these two currents exceed the maximum rating on the leds, the circuit will not work!
-Now try to connect the leds between red and grey, and black and grey. The anode on the led (the longer leg) must be connected to the positive voltage (the grey wire on my footswitch)!
-If this doesn’t work, the circuit inside the amp is probably not the same, and my design will not work. Let’s just hope it works!
Thanks, I’ll get you back shortly. I bought the amp around the same year. Just hoping that it works too.
When you say: “Now try to connect the leds between red and grey, and black and grey.”
I done it like on your picture. I removed the red and put a led between (reverb) and remove the grey (from the channel side) and put a led between. I didn’t touch the black wire. Should I put the led between the black and the lead or like your picture, the led between the grey on the other lead? I am french, so 🙂 I might be clumsy to understand…and I am also not good in electronic, even simple. 🙂
I added a couple of pictures, hope they will be helpful to You. There’s nothing wrong with being french 🙂