Kt Kingtronics Tells You How to Use a Multimeter to Detect Electrolytic Capacitors

A. Because the capacity of electrolytic capacitors is much larger than that of general fixed capacitors, the appropriate range should be selected for different capacities when measuring. In general, the capacitance between 1 ~ 47μF can be measured by R × 1k, and larger than 47μF can be measured by R × 100.

B. Connect the red meter to the negative pole and the black meter to the positive pole. At the moment of contacting, the pointer deflects to the right largely (for the same resistance, the larger the capacity, the larger the swing), and then gradually turn left until it stops at a certain point, which is the forward leakage resistance that is slightly larger than the reverse leakage resistance. The leakage resistance should generally be above hundreds kΩ, otherwise, it will not work properly. In the test, if there is no charging phenomenon in the forward direction and the reverse direction, that is the needle does not move, which means that the capacity disappears or the internal circuit is broken. If the resistance measured is small or zero, it indicates that the capacitor is large leakage resistance or has been broken and damaged, cannot be use any more.

C. For the electrolytic capacitor whose signs are unknown, it can be discriminated by using the above method. Frist, measure the leakage resistance at randomly and remember its swing. Then, exchange the test leads to measure a resistance. In two measurements, the large resistance is the forward connection, that is the black meter is connected to the positive pole and the red one is connected to the negative pole.

D. Via the multimeter to charge the electrolytic capacitor from the positive and the reverse side, the capacity can be estimated according to the magnitude of the swinging.