How to judge that the electrical fault is a potentiometer fault and how to repair it

Potentiometer is an electronic component commonly used in circuits. When it is used frequently, it sometimes fails, and the product cannot be used, such as: household potentiometer, the failure of the potentiometer is easier to show on the whole machine , Such as loud noise when turning the potentiometer, loud and small sound, and power switch failure. At this time, we need to detect the potentiometer, the method is as follows.

Potentiometer detection method

The detection method of the potentiometer. Use an appropriate ohm block to measure the total resistance of the potentiometer 1~3 to see if it is within the nominal value range. Connect the test leads between the terminals 1-2 or 2-3, and turn the potentiometer shaft slowly and repeatedly to see if the pointer of the meter changes continuously and evenly. Its resistance value should continuously change between the nominal value near zero ohms.

Common failures and repairs of potentiometers:

1. The malfunctions of the potentiometer include large rotating noise, internal open circuit of the pin, abrasion of the resistor body, burnout, and damage to the switch.

2. The main reason for the potentiometer with high rotating noise is due to the wear of the resistor body, which makes the contact between the movable piece contact and the resistor body poor, and the resistance value fluctuates from large to small, resulting in a "click, click" sound. You can use a multimeter. According to the aforementioned method to detect, you will find that the pointer has a jumping phenomenon.

3. For potentiometers with this kind of failure, the cleaning method can be used to troubleshoot the failure. That is, use tweezers to clamp a cotton ball dipped in anhydrous alcohol, bring the cotton ball close to the rotating shaft, inject alcohol into the resistor along the rotating shaft, and keep rotating the rotating shaft until the noise disappears.

4. When the potentiometer pin is internally disconnected, the potentiometer will not work, that is, there is no change in the current or voltage of the circuit when the shaft is rotated. For the volume potentiometer, there may be a silent failure or the phenomenon that the volume cannot be turned off. When a multimeter is used to detect the resistance between two fixed pins or between a fixed pin and a sliding contact pin, the resistance value is infinite or close to When it is infinite, it can be judged that its pin is open.

5. The carbon film resistor body will burn out severely due to overcurrent and cause an open circuit. It is generally inconvenient to repair the potentiometers whose pins are open or the resistor body is burned out, and replacement is adopted.