Troubleshooting of digital multimeters can be roughly carried out according to the following 5 methods.
1. Visual inspection.
You can touch the battery, resistors, transistors, and integrated blocks to see if the temperature rise is too high. If the newly installed battery heats up, the circuit may be short-circuited. In addition, the circuit should also be observed for disconnection, desoldering, mechanical damage, etc.
2. Waveform analysis.
Use an electronic oscilloscope to observe the voltage waveform, amplitude, period (frequency), etc. of each key point of the circuit.
For example, if the clock oscillator is oscillating, if there is no output from the oscillator, it means that the internal inverter is damaged, or the external components may be open.
3. Measuring component parameters.
For components within the fault range, conduct online or offline measurements, and analyze parameter values. When measuring resistance online, the influence of components connected in parallel with it should be considered.
4. Hidden troubleshooting.
Hidden faults refer to faults that appear and disappear from time to time, and the instrument is good and bad. This kind of failure is more complicated, and the common reasons include weak solder joints, looseness, loose connectors, loose contact of transfer switches, unstable component performance, and continuous breakage of leads. In addition, it also includes some external factors. For example, the ambient temperature is too high, the humidity is too high, or there are intermittent strong interference signals nearby.
5. Detect the working voltage at all levels.
Detect the working voltage of each point and compare it with the normal value. First, ensure the accuracy of the reference voltage. It is best to use a digital multimeter of the same model or similar to measure and compare.
In addition to the above possible reasons, the damage of the digital multimeter may also be due to the wrong measurement gear
For example, when measuring the AC mains, the measurement gear is set to electric blocking, in this case the table
Once the pen touches the mains, it can cause damage to the internal components of the multimeter in an instant.
Therefore, before using the multimeter to measure, be sure to check whether the measurement gear is correct.
After use, set the measurement option to AC 750V or DC 1000V,
In this way, no matter what parameter is mismeasured in the next measurement, it will not cause damage to the digital multimeter.
