To test a capacitor with a multimeter, discharge the capacitor, set the multimeter to test for resistance then interpret the reading. There are other testing methods other than resistance that can be used. Since capacitors store voltage, the multimeter is also capable of reading volts, so if the multimeter being used has a capacitance meter, the actual capacitance value is given.Continue Reading
Discharge the capacitor by placing a screwdriver or wire across the leads. This is done to prevent a shock that could damage the multimeter.
Since the resistance of the capacitor is tested, set the multimeter to read in the ohm range between 10,000 and 1,000,000 ohms.
Touch the probes to the capacitor's leads. If the capacitor is electrolytic, touch the red probe to the positive lead and the black probe to the negative lead. If the capacitor is not electrolytic, the polarity doesn't matter.
If the multimeter reads in the range of 10,000 ohms and increases to near infinity, the capacitor is normal. If the reading is very low or nothing, the capacitor has a short and is defective. If the reading is immediately infinite, the capacitor is both open and defective.
To test a transformer, obtain an oscillator and multimeter, sync the measuring devices, and connect the oscillator to the transformer to display a voltage reading. Equipped with the multimeter, use the oscillator to test AC signals of the transformer's wires to determine if the voltage is the appropriate reading for the transformer to operate correctly.Full Answer >
To test a MOSFET, touch the negative probe of a multimeter to the "source" of the MOSFET and the positive probe to the "gate" and then to the "drain," then touch a finger between the source and the gate and see if the multimeter reading rises. If the reading rises, then the MOSFET works properly.Full Answer >
To test the capacitor on a home air conditioning unit, shut off the power supply, discharge the unit and obtain the reading. If the reading is more than about six percent lower than the known rating, it is time to replace the capacitor.Full Answer >
Electrolytic capacitors are polarized with both a positive and negative. On through-hole capacitors the negative leg of the capacitor is identified with the negative symbol printed on the capacitor body and the positive leg is often longer. This design makes identification easier when assembling.Full Answer >