Multimeter for capacitance measurement - good or bad
Use the resistance ohms of the digital multimeter, and discharge the capacitor under test before measurement to prevent damage to the digital multimeter. The two levels of capacitance are not connected, it is best to use the appropriate resistance connection.
Measurement of capacitance: use resistance gear, according to the capacitance capacity to choose the appropriate range, and pay attention to the measurement of electrolytic capacitors for the black pen should be connected to the positive side of the capacitor.
①, estimate the size of the microwave method level capacitance capacity: can be based on experience or reference to the same capacity of the standard capacitance, according to the pointer swing of the largest size to determine. The reference capacitance does not have to withstand the same value, as long as the same capacity, such as an estimate of a 100μF/250V capacitance can be a 100μF/25V capacitance to reference, as long as they are the same as the pointer swings the maximum magnitude of the same, it can be concluded that the capacity of the same.
②, estimate the size of the capacitance capacity of the Pifa level: to use R × 10kΩ file, but can only be measured to more than 1000pF of capacitance. For 1000pF or slightly larger capacitors, as long as the needle is slightly swinging, you can think that the capacity is enough.
③, test capacitance leakage: more than a thousand microfarads of capacitance, can be used first R × 10Ω file will be quickly charged, and the initial estimate of capacitance capacity, and then changed to R × 1kΩ file continue to measure for a while, the pointer should not be returned, and should be stopped at or very close to ∞, or else there is a leakage phenomenon. For some dozens of microfarads below the timing or oscillation capacitance (such as colour TV switching power supply oscillation capacitance), the leakage characteristics of its requirements are very high, as long as there is a slight leakage can not be used, then can be in the R × 1kΩ file after charging and then change to the R × 10kΩ file to continue to measure, and the same needle should be parked at ∞ and should not be returned.
Capacitor damage generally has three states: short circuit, open circuit, capacity reduction.
Multimeter to measure the capacitance of short-circuit and open circuit is relatively easy.
Measurement of capacity reduction is slightly more complex, and the measurement will not be very accurate.
Measurement: Pointer multimeter measurement. Play to the resistance gear. The two pens are connected to any two feet of the capacitor, and then the two pens are adjusted to measure the two feet of the capacitor. Cycle several times. Each time to see the multimeter pointer swing amplitude, if the swing after not slowly back to the position, is a short circuit. If the pointer does not swing at all, it is an open circuit. If the pointer does not swing at all, it is an open circuit. If the pointer does not swing at all, it is an open circuit. If the pointer does not swing at all, it is an open circuit. If the pointer does not swing at all, it is an open circuit. If the pointer does not swing at all, it is an open circuit. See if the amplitude of the swing and return is the same. Is the same is good. The amplitude of the swing compared to the difference of so little does not matter. If the difference is too much, it is bad and should be replaced.
Measurement with a digital multimeter: turn it to the call mode. Measurement method is the same. If it is short-circuit, the multimeter will keep dropping ~ ~ ~ call. If it is open circuit, the multimeter will not react at all. If it is good, the multimeter will call from call to no call. The larger the capacity, the longer the call.
Capacitors have electrolyte in them, and the electrolyte dries out easily. Some of the electrolyte dried capacitors put in the ear shake, there is a low similar to ringing a bell inside. Of course, the sound is very low, not as crisp as ringing a bell. Such is also bad!
