How to use a multimeter to measure the capacity and quality of capacitors
Many digital multimeters nowadays come with capacitance settings, making it easy to measure the capacitance and its quality. The method of measuring capacitance is very simple. First, insert the black probe of the digital multimeter into the COM socket and the red probe into the Cx socket of the multimeter as shown in the above figure. According to the size of the measured capacitance, turn the multimeter range switch to the appropriate capacitance level. Then, use the red and black probes of the multimeter to contact the two pins of the measured capacitance (when measuring electrolytic capacitance, the polarity of the pins does not need to be considered). At this time, the reading displayed on the multimeter is the capacitance. If the measured capacitance is basically consistent with the nominal capacitance of the capacitor, it indicates that the capacitor is good.
The tested 47 μ F/35V aluminum electrolytic capacitor.
The above figure shows an aluminum electrolytic capacitor with a capacity of 47 μ F/35V. The measured capacity of the capacitor using a multimeter is 45.17 μ F.
When measuring capacitance, if the reading displayed on the multimeter is much lower than the nominal capacity of the capacitor, it indicates that the capacitor is damaged; If the measured reading is much larger than the nominal capacity, it indicates that the leakage current of the capacitor is too high and it is not suitable for use. If the capacitance gear of the multimeter is selected correctly during measurement, but the displayed reading is "1", it may be that the capacitor has broken down. At this time, the resistance value of the capacitor can be measured using the resistance gear. If the displayed resistance value is very small, it indicates that the capacitor has broken down and is damaged.
Like a mechanical watch, with a resistance of 10K, just watch the pointer swing back and forth to zero. Okay! On the contrary, it dries up. Similarly to a numerical table, most enthusiasts have two tools. (However, manual discharge is required after each measurement. The capacitance on the instrument should be soldered off one foot before measurement to avoid affecting the pointer. A multimeter is actually a resistance meter, and the capacitance on the meter is very small, such as decoupling, so its function will not be affected.)
Generally, the MF47 multimeter is used to set the resistance to 100m Ω. The probe measures the capacitance at both poles for two seconds, and then the probe is reversed. The probe first moves forward and then slowly moves backward, provided that the capacitance is small and discharged before measurement. This can measure whether the capacitor is short circuited and whether it is storing electricity, but cannot measure the capacitance of the capacitor. For reference only
Taking 9205 as an example, set the gear to the corresponding gear of the tested capacitor (if the tested capacitor is 10uf, then set it to the gear of 20uf). Connect the black probe to the COM hole and the red probe to the CF and MA holes. Discharge the capacitor to measure.
