To detect faulty capacitors, usually use a multimeter to detect
1. Fault detection of non-polar capacitors:
When testing, first perform mechanical zero adjustment on the pointer multimeter. Then select the Rx10k ohm range of the multimeter, touch the red and black test leads of the meter to the two pins of the capacitor to be tested respectively, and observe the change of the resistance value indicated by the multimeter.
If the moment the test pen is connected, the pointer swings slightly to the right and then returns to infinity; after changing the test lead, re-measure, and the pointer still swings slightly to the right and then returns to infinity at the moment the test pen is connected, it means that the capacitance is normal.
If the pointer of the multimeter swings to the right near 0 at the moment when the multimeter is turned on, it means that the capacitor has serious leakage or has been broken down.
If the instant the multimeter is turned on, the pointer cannot return to infinity after swinging to the right, indicating that the capacitor is leaking.
If the pointer does not move when the multimeter is turned on, it means that the capacitor is open.
2. Fault detection of electrolytic capacitors:
Electrolytic capacitors are polarized capacitors. Before testing, use a screwdriver or a spatula to discharge the remaining charge of the capacitor. Then connect the black test lead of the multimeter to the positive pole of the capacitor, and the red test lead to the negative pole, and observe the swing of the pointer of the meter.
At the moment when it is first turned on, the multimeter should deflect to the right by a large angle, and then return to the left. Until it returns to a certain place and stops, the resistance value measured at this time is the forward insulation resistance of the capacitor. The resistance measured after changing the test leads is the reverse insulation resistance of the capacitor.
If the pointer of the meter does not move, it means that the capacitance disappears or the internal circuit is broken.
If the forward and reverse insulation resistance of the capacitor measured by the meter is very small or 0, it means that the capacitor has a large leakage or an internal short circuit.
Digital Multimeter Detects Capacitive Faults
Put the digital multimeter in the capacitance gear, and select the appropriate gear according to the size of the electricity. After the capacitor to be tested is fully discharged, insert the two pins of the capacitor directly into the test hole for measurement; or use two test leads to directly touch the capacitor pins for measurement. At this time, the capacity of the measured capacitor will be directly displayed on the multimeter.
When measuring the electrolytic capacitor with a digital multimeter, after the capacitor to be tested is fully discharged, the red test lead of the meter should be connected to the positive pole of the capacitor, and the black test lead should be connected to the negative pole of the capacitor. What is measured at this time is the positive insulation resistance of the capacitor. Otherwise, The measured resistance is the negative insulation resistance.
Capacitor replacement skills:
1. The capacity of the replacement capacitor should be basically the same as that of the original capacitor.
2. High withstand voltage capacitors can replace low withstand voltage capacitors, but low withstand voltage capacitors cannot replace high withstand voltage capacitors.
3. Small-capacity capacitors connected in parallel can replace large-capacity capacitors; large-capacity capacitors connected in series can replace small-capacity capacitors.
4. The reverse series of electrolytic capacitors can replace the non-polar capacitors.
5. For high-frequency oscillation capacitors and power filter capacitors, ordinary capacitors cannot be used instead.
