Detect with buzzer
Using the buzzer gear of the digital multimeter, you can quickly check the quality of electrolytic capacitors. The measurement method is shown in Figure 5-14. Turn the digital multimeter to the buzzer gear, and use two test pens to contact the two pins of the capacitor Cx under test respectively. A short beep should be heard, then the sound will stop, and the overflow symbol "1" will be displayed at the same time. Then, swap the two test leads for another measurement, the buzzer should sound again, and finally display the overflow symbol "1". This situation indicates that the measured electrolytic capacitor is basically normal. At this time, you can dial to 20MΩ or 200MΩ high resistance and measure the leakage resistance of the capacitor to judge whether it is good or bad.
The principle of the above measurement process is: at the beginning of the test, the charging current of the meter to Cx is relatively large, which is equivalent to a channel, so the buzzer sounds. As the voltage across the capacitor continues to rise, the charging current decreases rapidly, and finally the buzzer stops sounding.
During the test, if the buzzer keeps sounding, it means that the electrolytic capacitor has been short-circuited; if the buzzer does not sound and the meter always displays "1", it means that the capacitor under test is open-circuited or the capacity has disappeared.
