How to use a multimeter to measure the capacity of capacitors and good and bad
Nowadays, many digital multimeters are equipped with capacitance files, which can easily measure the capacitance capacity and its good or bad. Measurement of capacitance is very simple, first of all, as shown in the above figure will be digital multimeter black pen inserted into the COM jack, red pen inserted into the Cx jack, and according to the size of the measured capacitance, the multimeter range switch will be rotated to the capacitance of the appropriate gear, and then use the multimeter red and black pens were contacted by the measured capacitance of the two pins (measurement of electrolytic capacitance, do not need to take into account the polarity of the pins), at this time, the multimeter display At this time, the multimeter shows the reading of the capacitance. If the measured capacitance and the nominal capacity of the capacitor is basically the same, that the capacitor is good.
A 47μF∕35V aluminium electrolytic capacitor, using a multimeter to measure the capacitance of the capacitor is 45.17μF.
In the measurement of capacitance, if the multimeter reading is much smaller than the nominal capacity of the capacitor, that the capacitor has been damaged; if the measured reading than the nominal capacity is much larger than the capacitor leakage current is too large, should not be used. If the measurement, the multimeter capacitance gear selection is correct, but the display reads "1", may be the capacitor has been broken, this time you can use the resistance file to measure the resistance of the capacitor, if the resistance value is very small, indicating that the capacitor breakdown damage.
Such as mechanical table, resistance 10K file, see the pointer swing back (reciprocating) back to zero can be, good! Instead of dry. Ditto the digital table a table, the same as the general hobbyists have two tools. (But after each measurement must be manually discharged. Capacitors on the instrument should be welded away from a foot before measuring, so as not to affect the pointer. Multimeter is actually a resistance meter, the table capacitance are very small, decoupling and so on, the function will not be affected.)
Generally is the use of MF47-type multimeter hit to 100mΩ resistance gear, the table pen to measure the capacitance of the poles for two seconds after the reverse measurement of the meter needle to move forward and then slowly move backward, provided that the capacitance capacity is small and discharged after the measurement. This can measure whether the capacitor is short-circuited and whether the storage of electricity can not measure the capacity of the capacitor. For reference only
Take 9205 for example, the gear will be played to the capacitance to be measured on the corresponding gear (such as to be measured capacitance of 10uf, then play to the 20uf gear). The black pen is connected to the COM hole, the red pen is connected to the hole with CF, ma, the capacitance will be discharged can be measured.
