Potentiometer failure detection and precautions for use2021

The potentiometer is a relatively commonly used electronic component. Due to frequent use, some failures will occur, and the failure of the potentiometer is easy to manifest on the whole machine, such as: the rotating noise is large, the sound is large and sometimes small, and the power switch Failure and so on. Today I will talk about potentiometer detection methods, potentiometer troubleshooting methods, and potentiometer use precautions.

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.

Potentiometer troubleshooting method

1. When a multimeter is usually used to detect the fixed pin terminals on both sides of the potentiometer, if the measured resistance value of the potentiometer deviates too much from the nominal resistance value, it may be that there is a short circuit inside the pin terminal of the potentiometer, etc. malfunction. So for dealing with this kind of failure, I suggest that you generally choose to replace the potentiometer. It is generally inconvenient to repair, because this kind of pin internal short circuit and other faults are caused by some internal components that have been damaged. Even if it is repaired, the resistor body will be seriously burned out due to overcurrent in use.

2. Regarding the common faults of the general potentiometer, there is a relatively large rotating noise during adjustment. The main reason is that the resistance body is worn out, which makes the contact between the moving piece contact and the resistor body poorly, which leads to the resistance value. Large or small, causing noise during adjustment. Then for the method of dealing with the noise failure of the potentiometer, first disassemble the potentiometer, and then add some industrial lubricant to the shaft of the potentiometer. The purpose is to reduce the friction when adjusting the shaft, so as to reduce the friction at the same time. Reduce the wear on the resistor body, so that this kind of noise failure can be eliminated in the use of the potentiometer.

3. 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.

4 The main reason for the potentiometer with large rotating noise is due to the wear of the resistor body, which makes the contact between the moving piece contact and the resistor body poor, and the resistance value fluctuates from large to small, resulting in a "click, click" sound. When the aforementioned method is used for testing, it will be found that the pointer has a jumping phenomenon.

5. For potentiometers with such failures, 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.

6. 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.

7. 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.

Precautions for using potentiometer

1. Before using the potentiometer, be sure to check the potentiometer carefully, for example, whether the lead-out terminals between the pins of the potentiometer are loose, and whether the contact is good and reliable. Otherwise, the use of potentiometers with faults will not only affect the normal operation of the equipment circuit, but also may cause damage to other components in the circuit.

2. When the potentiometer is installed in the circuit, pay more attention to whether the three pins of the potentiometer are correctly connected. If they are connected incorrectly, the use of the potentiometer may cause some volume adjustment failures or adjustments. Failure conditions such as the volume is not dead.

3. In addition to the rotary switch potentiometer, there is currently a push-pull switch potentiometer in the market. Then, for the selection of these two types of potentiometers with different specifications, we must distinguish clearly and use them.

4. Such as the maximum voltage on the potentiometer, the maximum current that each arm can provide, the maximum power that can be consumed, and the resistance that needs to be considered the most. Everything from power to noise. The error of a single resistor is usually +/-20% to +/-5%, and temperature will also cause the drift of the resistance value, so it is necessary to consider the accuracy, linearity, monotonicity of the potentiometer, and whether to consider other factors in the design. For example, the frequency response of the human ear to sound will be more important. Changes in resistance, cost and volume, and reliability such as assembly and humidity during power-off and power-up.