Introduction to the precautions for measuring capacitance with a multimeter
Before measurement, be sure to cut off the power and discharge. The discharging method is to find a metallic object such as a screwdriver. Hold the exposed part of the metal with the insulated handle and touch the two pins of the capacitor under test. For capacitor measurement, use a digital multimeter. Select the capacitor gear, then discharge the capacitor completely and insert the two pins into the capacitor measurement socket. Wait until the reading on the liquid crystal screen stabilizes, and the value displayed is the capacitance of the capacitor under test. If you want to measure the leakage situation, you can use the resistance gear of an analog multimeter for measurement. When measuring, for a capacitor with a small capacitance, you can set the multimeter to the RX1K or RX100 gear. When the two test leads are connected to the two pins of the capacitor and the reading on the dial is observed, the pointer will deflect clockwise. Then, after the capacitor is fully charged internally, since there is no current flowing, the pointer will deflect counterclockwise and return to infinity. The larger the angle of the pointer deflection indicates a larger capacitance. During the deflection process, the pointer should swing uniformly and then return to infinity, which initially indicates that the capacitor has no leakage. If the pointer suddenly slows down or does not return at a certain position on the dial, it indicates that the capacitor has leakage at a certain section. If the final display is infinity, it means there is no leakage. However, this is only a rough judgment. If you want to obtain an accurate value, you need to use a capacitance meter, a capacitor leakage tester, or an oscilloscope to observe the characteristics, which is generally not available to ordinary people. In addition, capacitors have a rated voltage value. The rated voltage value of an electrolytic capacitor is generally written on it. Some ceramic capacitors have no markings on them, so be sure to pay attention when selecting them.
