Notes on measuring capacitance with a multimeter
Select Rx1k or Rx100 mode for a pointer multimeter. Connect the black probe to the positive terminal of the capacitor and the red probe to the negative terminal of the capacitor. If the probe rapidly swings to the right and then slowly retracts to near infinity (∞ Ω), it indicates that the capacitor is normal and has a large capacity; If it does not reach infinity when returning, it indicates that the leakage current of the capacitor is large, and the pointer reading is the leakage resistance value of the measured capacitor (the leakage resistance of aluminum electrolytic capacitors should exceed 200k Ω before use); If the pointer does not swing to the right at all, it indicates that the capacitor has broken or the electrolyte has dried up and lost its capacity; If the pointer swings greatly, approaching 0 Ω, and does not return, it indicates that the capacitor has been broken down.
Precautions for using a multimeter to measure capacitance
Before measuring, it is necessary to cut off the power and discharge. The method of discharging is to find a metal object such as a screwdriver, hold it on the exposed part of the metal on the insulating handle, and place the two pins of the measured capacitor on the two pins. The capacitance measurement is measured with a digital multimeter, find the capacitance gear, and then discharge the capacitor. The two pins are inserted into the capacitance measurement socket or other LCD screen. The stable reading is the capacitance of the measured capacitor. If leakage is measured, the resistance range of the pointer type multimeter can be used to measure. When measuring, the small capacity capacitance multimeter can be placed in RX1K or RX100. When the two probes are connected to the two pins of the capacitor on the measurement dial, the pointer will deflect clockwise and then follow the display. After the capacitor is fully charged, the needle will discharge counterclockwise and return to infinity due to the absence of current flow, The larger the angle of the pointer, the larger the capacity. During the deflection process, the pointer needs to swing at a constant speed so that it can return to infinity. This indicates that there is no leakage in the capacitor. If the pointer suddenly slows down or does not return at a certain position on the dial, it indicates that the capacitor is leaking in a certain section. If it shows infinity at the end, it indicates that there is no leakage. However, this can only be a rough judgment. To find an accurate value, it is necessary to observe the characteristics with a capacitance meter, capacitance leakage tester or oscilloscope, which is impossible for ordinary people to possess. Capacitors also have a withstand voltage value, and the withstand voltage value of electrolytic capacitors is usually written on it. When selecting ceramic capacitors, it is important to note that some are not labeled on it.
