About Potentiometers
A potentiometer is a transducer that is used to change the displacement in an electronic device into a resistance change. What this means in practical terms is a change in what the device is able to do. For example, a potentiometer can be adjusted to make a lamp give off more or less light, or to make an amplifier produce different qualities of sound as desired by the musician using it. Many electrical devices, such as guitars, already have potentiometers in them, and these can either be swapped out for different types of potentiometer or modified directly.
Tricks for Electric Guitars
Musicians with skills in electronics and experience using a soldering iron can modify the sound in their electric guitars by modifying the potentiometer. Different guitars typically come with different potentiometers. Fenders usually start with a 250k potentiometer, more recent models of Les Paul come with a 350k potentiometer, and older Gibson guitars tend to have 500k potentiometers. This accounts for some of the difference in tone between different models. A 250k potentiometer will have a warmer sound, while a 500k potentiometer will sound brighter, and a 350k will be in between the two. One simple trick is to switch out the potentiometer for one with the desired tone.
Tricks to Replicate Older Guitars
Some musicians and electronics hobbyists with Les Paul guitars have attempted to rewire them at home in order to approximate the sound of an older Les Paul from the 1950s. In this case, the capacitor has to be replaced as well as the potentiometer, and both the brand and the type are important. The capacitors in the Les Paul should be replaced with NOS Bumble Bee brand .022uF/400v capacitors, and the potentiometer should be replaced with 500k potentiometers from CTS. Matching the potentiometer used in the original model is key when trying to replicate the sound of any older guitar.
Tricks for Repairing Potentiometers
If your potentiometer stops functioning and you don't want to simply replace it, there are some tricks you can use to get it working again. One is to take it apart, remove the plastic cover and swap out the phenolic wafer inside it for one that has not yet worn out. If another wafer is not available, you can use conductive paint to paint over the wafer and cover up any gaps that have developed in it. You should use either copper or silver conductive paint for this task. Some hobbyists claim that toner powder from a photocopier can be melted down and used for the same purpose. Another option is to take the wiper contacts in the potentiometer and bend them so that they contact different sections of the wafer that have not worn through yet. You should be aware that some brands of potentiometer, particularly cheaper ones, cannot be put back together if you take them apart.