Second, if it is necessary to judge whether the electrolytic capacitor is invalid online, please use ESR meter (equivalent series resistance) to judge. On-line measurement of ESR value can quickly pick out the defective electrolytic capacitors.

Turn the multimeter to 1K or 100 ohms, and connect the two probes to the two electrodes of the measured capacitor respectively. Observe the reaction of the hands. If the hands are close to zero soon, then slowly walk back (to infinity) and stop somewhere, it shows that the capacitor is basically good. The closer the return stop position is to infinity, the better the quality, and the farther it is, the more leakage. If the multimeter needle is set to zero or near zero soon, it means that the two poles of the capacitor have a short circuit fault and cannot be used. If the stylus does not move at all when the two poles of the capacitor are connected, it means that the internal connection of the capacitor has been disconnected and can not be used.

000p, suitable for measuring capacitance less than 2000pF;

20n, suitable for measuring the capacitance between 2000pF and 20nF;

200n, suitable for measuring the capacitance between 20nF and 200nF;

2μ file, suitable for measuring the capacitance between 200nF and 2μF;

20μ range, suitable for measuring the capacitance between 2μF and 20 μ f.