Resistance measurement with digital multimeter
Insert the red test pen into the "V/Ω" jack, select the appropriate resistance measurement range according to the size of the resistance, touch the red and black test pens to both ends of the resistor, and observe the reading. In particular, when measuring in-circuit resistance (resistance on a circuit board), the power supply to the circuit should be turned off first to avoid jitter in the reading. It is forbidden to use the resistor to measure current or voltage (especially AC 220V voltage), otherwise the multimeter will be easily damaged. In addition, the resistance level can also be used to qualitatively judge the quality of the capacitor. First short-circuit the two poles of the capacitor (touch both poles with one test lead at the same time to discharge the capacitor), then touch the two test leads of the multimeter to the two poles of the capacitor respectively, and observe the displayed resistance reading. If the resistance reading displayed at the beginning is very small (equivalent to a short circuit), then the capacitor starts to charge, the resistance reading displayed gradually increases, and finally the resistance reading displayed becomes "1" (equivalent to an open circuit), it means that the capacitor is OK If the above steps are followed and the displayed resistance reading remains unchanged, it means that the capacitor is damaged (open circuit or short circuit). Special attention should be paid to choosing the appropriate resistance range based on the size of the capacitor when measuring. For example, 47μF should use the 200k range, while 4.7μF should use the 2M range, etc.
Precautions
1. Pay attention to the correct selection of measuring range and red test lead socket. When measuring an unknown quantity, you should first adjust the range to the maximum, and then adjust it from large to small until it is suitable. If "1" is displayed, it means that it is over-cut and the range should be increased.
2. When not measuring, turn off the power supply.
3. When changing the range, the test leads should be disconnected from the measured point.
4. When measuring current, avoid overloading.
5. It is not allowed to use resistance or current settings to measure voltage.
