Troubleshooting a digital multimeter should generally start with the power supply. For example, after turning on the power, if the LCD cell displays, the voltage of the 9V stacked battery should be checked first to see if it is too low; Is the battery lead disconnected.

1, Visual inspection

2, Detect working voltage at all levels

3, Waveform analysis

For example, if the clock oscillator is on and the oscillation frequency is 40kHz. If the oscillator has no output, it indicates that the internal inverter of TSC7106 is damaged, or it may be due to an open circuit in external components.

The waveform of the {21} pin of TSC7106 should be a 50Hz square wave, otherwise it may be due to damage to the internal 200 frequency divider.

4, Measuring element parameters

5, Hidden troubleshooting