Introduction to Measuring Resistance with a Digital Multimeter
Measurement of AC and DC voltage using a digital multimeter
Insert the red probe into the "V/Ω" socket and select the appropriate voltage measurement range based on the voltage. The black probe contacts the "ground" terminal of the circuit, while the red probe contacts the point to be measured in the circuit. Special attention should be paid to the fact that the frequency of measuring AC voltage with a digital multimeter is very low (45-500Hz), and the voltage amplitude of medium to high frequency signals should be measured using an AC millivolt meter.
Insert the red probe into the "V/Ω" socket, select the appropriate resistance measurement range according to the size of the resistance, and touch the two ends of the resistance with the red and black probes respectively. Observe the reading. Especially when measuring the resistance on the circuit board, the power supply of the circuit should be turned off first to avoid reading jitter. It is forbidden to measure current or voltage using resistance mode (especially AC 220V voltage), otherwise the multimeter may be easily damaged. In addition, the use of resistance levels can also qualitatively determine the quality of capacitors. First, short-circuit the two poles of the capacitor (use one probe to simultaneously touch both poles to discharge the capacitor), then touch the two probes 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), and then the capacitor starts charging, the displayed resistance reading gradually increases, and after *, the displayed resistance reading becomes "1" (equivalent to an open circuit), it indicates that the capacitor is good. If the resistance reading displayed remains unchanged after following the above steps, it indicates that the capacitor is damaged (open circuit or short circuit). It is particularly important to choose the appropriate resistance range based on the size of the capacitor during measurement, such as 200k range for 47 μ F, 2M range for 4.7 μ F, and so on.
