About the common faults and solutions of MF47 multimeter
The failures and solutions that MF47 type multimeters often appear in student experiments.
Fault 1: 0.5 A fuse is blown, causing no current input fault, all gears cannot be measured. After disassembling the multimeter, measure the input fuse and found that the fuse has been blown. Replace it with a fuse of the same model and specification (the fuse specification of the MF47 multimeter is 250 V/0.5 A).
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Fault 2: DC voltage block failure, the three voltage divider resistors of 1 V, 2.5 V and 10 V block are connected to the three voltage dividers. If the DC voltage is 1 V, it is 15 k. If there is a burnout or open circuit phenomenon in the 30 kQ with 2.5 V block and 150 kfl with 10 V block, the measurement of other gears may be inaccurate in the DC voltage block. If the resistance in the DC voltage block is 2.69 k. If the core 2 resistance is open or burned out, the DC voltage block will all fail.
Fault 3: The DC current block is faulty, and several shunt resistors are burned out. If you misuse these three resistors, 7-2 and Yi, to measure large current or high voltage, it is easy to burn the shunt resistor. Since the shunt resistor has a small resistance value and is easy to be burnt out, the varistor is designed for overvoltage protection in the 500 mA DC current block to prevent the meter head from being burnt when the current block is used to measure the voltage.