Guitar Pedal Repair Short Guide

Here are some tips when diagnosing a guitar pedal. Remember that some pedals have warranties on them and you should send them in and have it repaired. This is more a guide for pedals without warranties and any steps followed from this site is at you own risk. It's always good to get a bit of electronics basics before diving into a pedal if you aren't already familiar.

1) Get all the information about the pedal first.
a)When did it stop working and what happened?
b)What is the pedals track record? Did it see the rigors of the road or stayed on the shelf at home in a temperature controlled studio?
c)Research the problem online. The Internet is a powerful tool and more often than not there are people out there with the same pedal problems and have conveniently posted a solution.

2)What does the pedal do when its powered up? If you have the correct battery or power supply voltage, the cables you are using are good, your guitar is good, and you amplifier is good, then it's time to get into the pedal.

3) Always have something to put all the hardware and parts in. Make sure you keep note of what screws go where. I've made a few mistakes when I put the entire pedal together and I forgot to put a couple washers on to the potentiometers.

4) Check for any visible signs of problems. Broken wires, broken leads on components, burn marks or discoloration, and broken solder joints. Most of the time a broken solder joint just needs to be reheated with a soldering iron and it's good to go. In the case of burn marks or discoloration, it could be a sign that something is getting way to hot or the component has burned out and is now damaged. So the component can just be replaced. One thing to watch for, is what caused the component to fail? If the component itself wasn't the problem but something else is, the component will continue to blow and the really problem needs to be found.

5) If there aren't any visible signs, do the tapping technique. Grab a pencil or some non-conductive object and lightly tap the PCB while the pedal is on and you are playing guitar. If you can hear your guitar come through when you tap, find the spot where the tapping helps the most. There could be a bad solder joint or there could be a break in the PCB trace. To fix the bad joint just reheat it with an iron and/or add a bit of solder. In the case of a broken trace, you need to find which trace it is. Use a multimeter and check continuity between the solder joints at the ends of a trace. If you get one without continuity that is the culprit. To fix this make a jumper wire between the two solder joints at the ends of the broken trace and solder it in. This will solve the broken trace problem. I repaired a Digitech Whammy pedal with this method.

6) Check to make sure that nothing is grounding out either where it shouldn't be. Use a multimeter and check continuity between the signal path and ground. From there find the near by culprit. I've had a guitar's potentiometer solder lugs making contact with the shielded cavity.

7) Semi-conductors are usually the first thing to go in a pedal if its a component. Sometimes the easiest thing to do is start swapping things out and see if it works. It's possible that a resistor is bad, but very unlikely. To check a resistor use a multimeter and check its resistance. It should be close to it's value. Capacitors can be checked by measuring resistance. With a capacitor the resistance should be well above 15K ohms and it should just rise up as you measure. Inductors can be checked for continuity and the DC resistance like a resistor.

8) If you've done these steps but are still having problems it is time to hand it over to a professional or if you have the equipment, do a signal trace. This is a long process, but it can be helpful when wondering where the signal is actually going and where it ends. The equipment needed is a function generator and an oscilloscope. Apply a 20mV 1KHz sine wave on the input of the pedal and check where the signal is going or what is happening to it with the oscilloscope. It also helps to get a hold of the schematic. Sometimes companies don't mind sending schematics, but if not check search engines. You may stumble across someone who has went through the same problems and posted a schematic that they have spent hours making.

I hope this guide helps. I've used these steps to repair pedals, amplifiers, guitars, and anything else that is electronic audio equipment. Don't be afraid to get your hands dirty, but remember know what you are doing first. Get some basic knowledge of electronics. A great website to go to is www.allaboutelectronics.com. The author even has a downloadable pdf format of the entire online book for free. This comes in handy if you don't have immediate Internet access. Even after reading you don't feel comfortable leave the repair work to a professional because they need to get paid. Good luck everyone!