America's Pedal - FX switch repair

The switch used in DOD's FX-series pedals is rather fragile and poorly protected, and is easily damaged through normal use and abuse. As the switch wears out, it becomes difficult to turn on/off -- either it takes several attempts, or it cannot be turned off/on at all. Fortunately, replacing a worn-out or touchy switch is a relatively simple repair.

Before you begin, make sure you've ruled out a dying 9V battery as the problem. Just like Boss and Ibanez pedals with FET switching, a dying battery can mimic the symptoms of a worn switch in DOD FX-series pedals. (DOD included an insert with its pedals, printed on red paper, to alert users that "battery replacement is indicated when unit will not switch from effect to straight through.") A dying battery can have enough juice to turn the pedal on and produce the effect, but not enough power to turn off the pedal via its flip-flop circuit. If the switch still appears touchy with a new battery or with the proper power supply, then the problem is likely is a worn switch.

Disclaimer: This tutorial assumes no knowledge of electronics, but does assume the reader knows their way around a soldering pen. If you've ever swapped out a pickup, pot, or switch in an electric guitar, then replacing the switch in a DOD pedal should be much easier by comparison. Although the repair described below is relatively simple with just two wires that need to be unsoldered/re-soldered, please be sure to practice your technique on something more disposable if necessary, or seek out an authorized DOD/DigiTech repair shop. By reading further, you agree that AmericasPedal.net and the authors of this webpage have NO legal or financial liability for botched repairs or any consequences thereof, including (but not limited to) bad tone, fire, injury, death (metal), and/or grunge.

Recommended tools:

• solder pen (25-30 watts)
• electronics-grade solder (preferably lead-based 60/40 rosin core, since that's probably what was used in your pedal)
• Phillips and flathead screwdrivers, and an adjustable wrench or a 10mm socket driver
• a solder sucker bulb or a desoldering braid
• a so-called "third hand" and/or a pair of heat sink soldering tweezers (see the links page)
• a replacement switch from DOD, Small Bear Electronics, etc. (see the links page)
• something to use as padding -- cloth, bubble wrap, whatever's handy -- to place on your work surface to minimize scratches, and another piece to put between the trace side of the circuitboard and the pedal's casing, to minimize the risk of broken traces on the circuitboard during the repair

Unlike (older) Boss pedals, the pots on DOD's FX-series pedals are connected to the main circuitboard as one assembly. Carefully remove the knobs from the pedal, and use a 10mm socket driver to remove the nuts holding the pots to the casing. Then gently pry the main circuitboard out of the casing, shifting it toward the back (battery end) of the pedal. (Be careful not to lose the lock washers mounted inside the pedal's casing against each pot's body.) We recommend that you place something (a soft cloth, thin bubble wrap, anything) between the trace side of the circuit board and the casing, to help prevent damage to the traces.

With the main circuitboard out of the way, you will see a smaller circuit board just below the treadle (photo 1), with two wires soldered to it at opposite corners. Unsolder both wires, then use a screwdriver to remove the screw that affixes the smaller circuitboard to the casing. Your pedal may also have a wire clip (not shown here; presumably to help adjust spring tension in the treadle) that is also held by this screw; make a careful note of how it was arranged for correct replacement after the new switch is installed.

With the smaller circuitboard removed from the pedal's casing, examine the way the old switch is mounted on it. Note that only two of the four legs of the switch are actually soldered to the circuitboard, at opposite corners (photo 2). It may be possible to clean the switch rather than replacing it, but if there is any mechanical damage to the "button", or if the switch has very little tactile "play" when pressed, it is probably damaged beyond repair. A new switch will audibly "click" or "pop" when pressed, with a noticeable range of travel as it is pressed.

In addition to the solder, the switch is held in place by the "spring action" of its legs. As you heat the solder, use a small flat-head screwdriver as a wedge to "pop" out the old switch, one side at a time (photo 3). A "third hand" or a pair of heat sink soldering tweezers (shown) is very helpful at this stage.

With the old switch removed, use a solder sucker bulb to remove excess solder from the two mounting holes that were used to solder the switch to the board (photo 4). Then snap the new switch into place, making sure that its base is flush with the smaller circuitboard, and re-solder the two corners.

Screw the small circuitboard back into the pedal's casing, ensuring that it is mounted flat to the inside of the casing. (If your pedal had a wire clip, make sure it is correctly re-installed as well.) Finally, re-solder the two lead wires (photo 5). Before you re-assemble the pedal, it might be worthwhile to install a battery and plug a 1/4" cable into the pedal's Input to verify the new switch turns the LED on and off without problems.

Other notes:

• In early DOD FX-series pedals (1982-83?), the switch was mounted directly on the pedal's casing instead of a small circuitboard. On these pedals, it may be necessary to remove the treadle to access the switch.
  
  
• For the FX15 Swell Pedal and the 220 Momentary Foot Switch, note that the wire leads and the footswitch are soldered to adjacent corners, instead of opposite corners.
  
  
• In all final-series pedals, the smaller footswitch was directly mounted to the main circuitboard. We have never tried to replace a footswitch on a final-series pedal, but from experience with Ibanez 5-series pedals, soldering/unsoldering a switch from a circuitboard without frying adjacent components will require a delicate touch.

We hope you found this tutorial to be helpful, and welcome any comments or suggestions for how to make this page better/easier to follow.

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