Diode gear or resistance gear can be used. If the diode gear is used, use the test pen to measure the point to be measured. If the circuit board is short-circuited, it will beep. If some multimeters have an indicator light on, or the resistance gear , if it is a short circuit, the display of the multimeter is zero.
1. Multimeter, also known as multiplex meter, multimeter, three-meter, multimeter, etc., is an indispensable measuring instrument in power electronics and other departments. Generally, it is mainly used to measure voltage, current and resistance. A multimeter is a multi-function, multi-range measuring instrument. Generally, a multimeter can measure DC current, DC voltage, AC current, AC voltage, resistance and audio level, etc., and some can also measure AC current capacitance, inductance and semiconductor. some parameters etc. Multimeters are divided into pointer multimeters and digital multimeters according to the display mode.
2. Measurement of DC voltage: First, insert the black test lead into the "com" hole, and the red test lead into "V Ω". The value can be read directly from the display screen. If it is displayed as "1.", it means that the range is too small, then the range should be increased before measuring the industrial electrical appliances. Select the knob to a range larger than the estimated value (note: the values on the dial are the maximum range, "V-" means DC voltage range, "V~" means AC voltage range, "A" is current range), then set the The test leads are connected to the power supply or both ends of the power supply; keep the contact stable. If "-" appears on the left side of the value, it means that the polarity of the test lead is opposite to that of the actual power supply. At this time, the red test lead is connected to the negative pole.
3. Measurement of AC voltage: The test pen jack is the same as the measurement of DC voltage, but the knob should be turned to the required range at the AC gear "V~". There is no positive or negative AC voltage, and the measurement method is the same as the previous one. Whether measuring AC or DC voltage, pay attention to personal safety and do not touch the metal part of the test pen with your hands.
4. Resistance measurement: turn the range switch to the appropriate range of Ω, insert the red test lead into the V/Ω hole, and the black test lead into the COM hole. If the measured resistance value exceeds the maximum value of the selected range, the multimeter will display .1. At this time, a higher range should be selected. When measuring resistance, the red test lead is the positive electrode, and the black test lead is the negative electrode, which is the opposite of the pointer type multimeter. Therefore, when measuring components with polarity such as transistors and electrolytic capacitors, you must pay attention to the polarity of the test leads.
5. Use a multimeter to measure the current: first select the range, the multimeter's DC current file is marked with "mA" and has three ranges of 1mA, 10mA, and 100mA. The selection of the range should be based on the current in the circuit. The multimeter should then be connected in series with the circuit under test. After the corresponding part of the circuit should be disconnected, connect the multimeter test leads to both ends of the breakpoint. The last correct reading, the scale line of the DC current file is still the second line. For example, when the 100mA file is selected, the third row of numbers can be used, and the reading can be multiplied by 10.
6. Use a multimeter to measure capacitance: some digital multimeters have the function of measuring capacitance, and their ranges are divided into five ranges: 2000p, 20n, 200n, 2μ and 20μ. When measuring, the two pins of the discharged capacitor can be directly inserted into the Cx jack on the meter board, and the displayed data can be read after selecting the appropriate range.
