A potentiometer is a variable resistor. Like a resistor, you can test potentiometers (also called “pots”) with your multimeter. As you can see in Figure you can connect the meter to either end of the conductive material. With the multimeter applied to points 1 and 2, turning the dial shaft in one direction increases resistance. But with the meter applied to points 2 and 3, turning the dial in the other direction decreases resistance.


The material used for the conductive surface of the pot can take many forms, including cermet (a combination of ceramic, glass, and precious metals), carbon, wire, and conductive plastic. This conductive surface can break off, get dirty, or burn out. A pot sometimes goes bad because something damages the surface. As you turn the shaft of the potentiometer, use your multimeter to make note of any sudden changes in resistance, which may indicate an internal fault. If you find such a fault, you should replace the pot with a new one.