Anyone who owns a cheaply made MXR command series guitar effects pedal from the early 80’s knows that its biggest weak point is its on/off foot switch, which is made of plastic and breaks quickly. I own the M-163 Sustain pedal and I really like its sound. It is precise and quiet, and when the foot switch finally broke, I figured there must be a way to replace it with a normal high quality foot switch. I have seen units on eBay where the owner moved the circuit board into a normal metal case with high quality pots, jacks and switch, however I wanted the look of the vintage unit as much as possible. If you have one of these command series effect units with broken switch, this might bring it back to life. The picture above is what the unit looks like when new. The actual electrical switch is under the spring loaded panel with the MXR logo.

Supplies

Double pole double throw (DPDT) foot switch

wire

Soldering gun and solder

Glue

Piece of flat plastic

Balck paint

Step 1: Replace Switch

Open the unit and unsolder the remains of the broken switch. It is a physical double pole double throw (DPDT) switch where one pole switches the unit on and off, and the other switches the LED on and off. This can be replaced with a high quality DPDT guitar pedal switch. Squeeze and remove the large movable plastic outer part (with MXR logo) that contacts your foot. You now have a nice hole in which to install your new switch. You might find that you need to Dremel, shave or scrape a wider area inside for the base of the switch to fit.

Step 2: Connect Wires

A rectangular capacitor will need to be unsoldered and relocated out of the way of the switch. I moved it about 1 inch with the yellow wires. The switch and circuit board have six contacts, of which only five are used.

-------------
|  A1   B1  |
|  A    B   |
|  A2   B2  |
-------------

In the above diagram A is switched between A1 (effect) and A2 (no effect)

At the same time B is switched between B1 (LED on) and B2 (LED off). The LED itself only uses B and B1, so the B2 contact is unused.

Solder wires from the circuit board to the corresponding lugs on the switch. There is a 50% chance you will wire the LED part incorrectly so that it is lit when the unit is off. Correct by moving the wire from B1 to B2.

Step 3: Finish

I glued a large flat black painted plastic panel to the top to add additional rigidity when mounting the switch. I liked the part that had the MXR logo so I glued it back on to the top. Lastly test it out before sealing it up. Once you close it up try not to open it ever again as the original parts are cheap and delicate and excessive movement can stress and break the wires or connections.