Digital multimeter screen has a digital display function can not be used, how is it?
There are generally two possibilities for this situation, one is that the meter pen and the input channel of the measured parameter are malfunctioning, resulting in the analog-to-digital converter inside the multimeter not being able to read the signal; the other is that the analog-to-digital converter inside the multimeter is damaged. Here we introduce these two cases respectively.
1,Quick judgment of the multimeter analog-to-digital converter good or bad
The questioner said that the display shows that the function can not be used. If the data shown on the display is disorganized, and use the multimeter to measure the voltage, resistance and other parameters, the multimeter will not change the number of displays, then we have to suspect that it is not inside the analog-to-digital converter is bad. Here to ordinary 3 ½ digital multimeter commonly used analog-to-digital converter ICL7106 as an example, to introduce the analog-to-digital converter good and bad quick judgment. As shown in the figure above, the ICL7106 constitutes a 200mV DC voltmeter. Normal operation, ICL7106 V + terminal (1 foot) and COM terminal (32 feet) between a stable 2.8 ~ 3.0V voltage, and the voltage will not change with the change of the multimeter battery voltage, so we just use another multimeter to measure the ICL7106 1 foot and 32 feet of the voltage between the feet, to see if it is the above values, if the measured voltage and the above voltage deviation If the measured voltage deviates from the above voltage, we can basically judge that the analog-to-digital converter or its peripheral components have problems. At this point you can first check the ICL7106 external components, and then determine whether ICL7106 is damaged.
2, the multimeter pen and input channel failure judgment
After confirming that the analog-to-digital converter of the digital multimeter is not a problem, you can first set the range switch to DC 200mV file to see if the number shown on the display is "000.0", adjusted to the resistance file to see if the number shown is "1". If you rotate the range switch, the display of the number of variable, that is, the meter pen internal disconnection, then you can through the resistance file or buzzer file to determine which pen has a problem. In addition, there is a fuse at the input of 200mA and below current file of digital multimeter, if this fuse is blown, it will cause the current file can not be used.
