How to determine if a dial potentiometer is broken?

Thumbwheel potentiometers are commonly used for volume adjustment. Available in 3-pin and 5-pin versions, they are widely applied in audio equipment. When audio devices malfunction, how can you tell if the thumbwheel potentiometer is faulty?

Follow the methods below for troubleshooting:

1. Pry open the four pins on the black base of the potentiometer, then wipe the resistance winding with alcohol and check if the performance improves.

2. If your multimeter reads 9.7 on the 200Ω range, this reading is abnormal by specification.

3. Connect the multimeter probes to the two outer pins and measure the total resistance. The nominal resistance is 100Ω with a tolerance of ±5%, so readings between 95Ω and 105Ω are normal.

4. A reading of 0.5Ω when turned to the minimum position complies with our factory specifications. This is caused by the potentiometer’s inherent zero-position resistance, plus wire resistance (also known as length resistance) of the copper or aluminum wires on the test probes.