Multimeter troubleshooting circuit board short circuit faults
Multimeter diode file or resistance file can measure circuit board failure, if the diode file with the pen to measure the points to be measured, if the circuit board is short-circuited, it will ring, if some of the multimeter on the light, or resistance file, it is short-circuited, then the multimeter display is zero.
1. Multimeter, also known as multipurpose meter, multi-purpose meter, three with the meter, traditional meter, etc., is an indispensable measurement instrument for power electronics and other departments, generally to measure voltage, current and resistance as the main purpose. Multimeter is a multi-function, multi-range measurement instrument, general multimeter can measure DC current, DC voltage, AC current, AC voltage, resistance and audio level, some can also measure AC current, capacitance, inductance and semiconductor some parameters. The multimeter is divided into pointer multimeter and digital multimeter according to the display mode.
2. DC voltage measurement: first of all, the black pen into the "com" hole, the red pen into the "V Ω". Values can be read directly from the display, if the display is "1.", it is shown that the range is too small, then we need to increase the range and then measure the industrial appliances. Select the knob to a range larger than the estimated value (Note: the values on the dial are the maximum range, "V-" that DC voltage gear, "V ~" that AC voltage gear, "A" is the current file), then connect the meter pen to the power supply or power supply terminals; keep the contact stable. If there is a "-" on the left side of the value, it indicates that the polarity of the pen is opposite to the actual power supply polarity, and the red pen is connected to the negative pole at this time.
3. AC voltage measurement: the pen jack and DC voltage measurement, but the knob should be played to the AC file "V ~" at the required range can be. AC voltage is not positive or negative, the measurement method is the same as the previous. Whether measuring AC or DC voltage, we must pay attention to personal safety, do not touch the metal part of the pen with your hands.
4. Resistance measurement: Set the range switch to the appropriate range of Ω, insert the red pen into the V/Ω hole, and the black pen into the COM hole. If the measured resistance value exceeds the maximum value of the selected range, the multimeter will display .1. When measuring resistance, the red pen is positive and the black pen is negative, which is the opposite of the pointer multimeter. Therefore, when measuring transistors, electrolytic capacitors and other components with polarity, you must pay attention to the polarity of the pen.
5. Measurement of current with a multimeter: first of all, select the range, the multimeter DC current file labeled "mA" has 1mA, 1omA, 100mA three ranges. Select the range, should be based on the size of the current in the circuit. Then the multimeter should be connected in series with the circuit under test. The corresponding part of the circuit should be disconnected, and then the multimeter pen should be connected to both ends of the breakpoint. Finally, the correct reading, DC current file scale line is still the second, such as the selection of 100mA file, available in the third line of figures, readings can be multiplied by 10.
6. Measurement of capacitance with a multimeter: some digital multimeter has the function of measuring capacitance, the range is divided into 2000p, 20n, 200n, 2μ and 20μ five files. Measurement can be discharged capacitance of the two pins directly into the table on the Cx jack, select the appropriate range can be read after the display data.
