The main requirements for potentiometer are: ① the resistance meets the requirements. ② The contact between the central sliding end and the resistance body is good and the rotation is smooth. For potentiometer with switch, the switch part shall act accurately, reliably and flexibly. Therefore, the performance of the potentiometer must be checked before use.

1. Resistance measurement: first, select the appropriate resistance gear of the multimeter according to the resistance value of the potentiometer to be measured, measure the resistance value, that is, the resistance value between the two ends of AC, and compare it with the nominal resistance value to see whether they are consistent. Rotate the sliding contact at the same time, and its value shall be fixed. If the resistance is infinite, the potentiometer is damaged.

2. Then measure the contact between the center end and the resistor, that is, the resistance between the two ends of BC. The method is that the ohm gear of the multimeter is in the appropriate range. During the measurement process, slowly rotate the rotating shaft and pay attention to observe the reading of the multimeter. Under normal conditions, the reading changes steadily in one direction. If there are phenomena such as jumping, falling or impassability, it indicates that the movable contact has the fault of poor contact.

3. When the center end slides to the head end or end, the resistance between the center end and the coincident end is 0 in the ideal state. In the actual measurement, there will be a certain residual value (generally depending on the nominal value, generally less than 5 Ω), which is a normal phenomenon.