Causes and repair methods of carbon film potentiometer failure2021

Electronic components such as potentiometers may malfunction when we use them all the time, because even the most sophisticated instruments may malfunction.

Carbon film potentiometers will have the following failures: large rotating noise, internal open circuit of the pin, resistance body wear, burnout, switch damage, etc. Let's analyze the causes and treatment methods of these failures.

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Causes and treatment of large rotating noise of carbon film potentiometers

The main reason for the large rotating noise of the carbon film potentiometer is 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. At this time, you can use a multimeter to test according to the aforementioned method, and then you will find that the pointer is jumping.

For the carbon film potentiometer with this kind of failure, you can first use the cleaning method to eliminate the failure, that is, use tweezers to clamp a cotton ball dipped in anhydrous alcohol, and then use the cotton ball to approach the rotating shaft, so that the alcohol is injected into the resistor along the rotating shaft. And keep rotating the shaft until the noise disappears.

Causes of internal open circuit in pins of carbon film potentiometers and treatment methods

When the carbon film potentiometer pin is open, there will be a phenomenon that the carbon film potentiometer does not work, that is, there is no change in the current or voltage of the circuit when the shaft is rotated. For the volume carbon film 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 when it is close to infinity, it can be judged that its pins are internally disconnected.

Carbon film resistors will also be severely burned out due to overcurrent, causing an open circuit. For carbon film potentiometers whose pins are open or whose resistors are burnt out, it is generally inconvenient to repair, and a replacement method is adopted.