Maintenance of Common Malfunctions of Digital Multimeter

A digital multimeter is a portable instrument with high sensitivity, intuitive readings and the ability to measure various items . It can be used to measure current, voltage , resistance, etc. In addition, it can also judge the performance of triodes , diodes and other components, which is a common tool for radio work. However, due to its fragility, it is often damaged due to improper use. As an instrument, it is inevitable to encounter some faults during use. The following is a detailed description of several common fault solutions .

1. There is no display when booting.

Causes and measures: Check whether the fuse, power supply circuit, and display are damaged, and whether the battery voltage is too low.

2. Abnormal DC voltage file 

Causes and measures: Short-circuit the +IN and -IN of the A/D converter, and if the displaythe DC voltage input part before the A/D converter. If the DC voltagefile is abnormal, it is usually because the I/V converter orAC/DC converter is damaged  .

3. The ohm file is abnormal

Cause and measures: It may be caused by the open circuit .

4. The capacitor file is abnormal

Causes and measures: Mainly the integrated block of ICM7556 is damaged .

5. When measuring, the deviation of is too large

Causes and measures: Generally, the transfer switch is in poor contact , just wipe it with absolute alcohol .

6. The deviation of the AC voltage file is too large

Cause and measures: Adjust the calibration potentiometer in the AC/DC conversion circuit . The deviation of each gear is too large, and the reference voltage value should be adjusted ( normal value 100mV).