Correct opening method for potentiometer repair

The potentiometer is a commonly used electronic component in the circuit. Some potentiometers may have some minor faults under long-term operation. The faults caused by the potentiometer are easier to show on the whole machine, such as noise when the potentiometer is turned. It is loud, the sound is loud and sometimes small, and the power switch fails. 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.

Today I will summarize the four ways of potentiometer repair

One is the friction cleaning method. At the beginning, the wear of these potentiometers was not serious. The only problem that appeared was that the sound appeared noisy or the volume fluctuated up and down during the adjustment, and there were some clutter on the screen. This was mainly due to the intrusion of the potentiometer during use. Dust or contact spring generates dust under constant friction with the carbon film, which contaminates the contacts, resulting in poor contact between the contact spring and the carbon film. For this kind of problem, the method I often use: First, continuously slide or rotate the potentiometer. This can remove the dirt on the contact and the carbon diaphragm, so that the contact becomes smooth and clean, even if it is not cleaned. The equipment temporarily returns to normal, which is a good way to solve temporary problems. In order to further solve the problem, we can clean the potentiometer with cleaning fluid after friction, thoroughly wash off the dirt on the carbon diaphragm of the potentiometer, and make the reed and the carbon diaphragm have good contact.

The second is the substitution method. Some potentiometers are severely worn and the friction cleaning method cannot solve the problem at all. For example, the contact reed and the carbon diaphragm are broken. I use the replacement method to solve such problems. First remove the damaged potentiometer from the device, and then separate it, replace the broken reed and carbon diaphragm with the good ones in the old potentiometer, and then combine it, but don’t do it before combining. Forget to clean first. If the dirt on the reed contacts cannot be cleaned, we can also polish the contacts to ensure that the newly formed potentiometer can function normally in the equipment.

The third is the reed diversion or self-made method. Some potentiometers are damaged because the contacts wear off the carbon film on the carbon film, resulting in poor contact between the contacts and the carbon film and causing malfunctions. At this time, I adjust the angle of the reed so that the contact of the reed is in contact with the carbon film. The unworn part of the carbon diaphragm is in contact to eliminate the fault: open the potentiometer, it can be seen that the reed and the original sliding track are rubbed, so that the surface of the carbon diaphragm has more obvious scratches, causing the reed to contact The carbon diaphragm is in poor contact. After cleaning, use needle-nose tweezers to adjust the reed so that it leaves the original sliding track, and the reed is in good contact with the carbon diaphragm that is not worn. The damage of some potentiometers is caused by the contact of the reed being worn away. If there is no replacement in this situation, we can also use copper to make a solution.

The fourth is the lubrication protection law. In order to prolong the service life of the repaired potentiometer, I often apply a little silicone grease on the carbon diaphragm of the potentiometer (sewing machine oil can also be used). The advantage of this is that it can prevent arcing, and the lubrication effect of silicone grease is reduced. The friction between the reed and the carbon diaphragm is reduced, so that the resistance change of the potentiometer during tuning is balanced and smooth, and the effect is good.

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.

The appearance of the potentiometer has a long history, and it is used in a wide range of fields in various ways, such as constant adjustment and measurement. The most common is to set and fine-tune the resistance value to fine-tune the circuit, set the level and adjust the gain, etc. Potentiometers are also used to design position feedback in robots and industrial equipment. All aspects of the switch potentiometer need to be considered, and need to be set according to the various needs of a specific application.