First, the pointer multimeter DC voltage file fault phenomenon and causes
1, no indication of the watch hand
Voltage part switch public node welding; The minimum range range multiplier resistance is disconnected or damaged.
2, individual ranges do not work, but other ranges work switch contact is not good or contact burned out; The switch contact connection is disconnected or unwelded from the additional resistance.
3, small range error, large range error small range multiplier resistance fault, such as variable value, short circuit and so on.
4, check to a certain stop, each stop is blocked when the multiplier resistance of that range begins to fail to weld or break the line.
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Second, the pointer multimeter AC voltage file fault phenomenon and causes
1, pointer swing amplitude small rectifier breakdown.
2, the error is about 50% lower in the full wave rectifier, there is a breakdown.
3, the low indicator value of the rectifier performance is poor, the reverse resistance is reduced.
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Third, digital multimeter DC voltage file fault phenomenon and causes
1. The DC voltage file fails
Check whether the transfer switch is in poor contact or open circuit;
Check whether the resistance in series of the DC voltage input circuit is open circuit failure;
2, DC voltage measurement display value is too large
Check whether the resistance value of the partial voltage resistor is equal to the nominal value;
Check whether the transfer switch has a string file.
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Fourth, digital multimeter AC voltage file fault phenomenon and causes
1. The AC voltage file fails
Check whether the transfer switch is in poor contact;
Check whether the integrated operational amplifier in the AC voltage measurement circuit is damaged;
Take the multimeter apart to measure the fuse inside the multimeter, generally your situation is caused by the open fuse... If it's a digital meter with an open fuse inside, the multimeter will always show 1 no matter what you're measuring, and one more thing, if you're a digital meter, maybe you pressed the HOLD button... Save the last data..... First check if you have pressed the HOLD button. If not, take the multimeter apart. First measure the fuse. If the value of the measured fuse is 1, it means that the fuse is open, and you are looking for a multimeter.
Frequency is too high! The set frequency of the multimeter is only 50Hz, and if the diode is connected, half of the time there is no voltage and half of the time there is voltage! The voltage is measured half the time!