Five Troubleshooting Methods for Digital Multimeters
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 welding of solder joints, looseness, looseness of connectors, poor contact of transfer switches, unstable performance of components, 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 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 caused by the wrong measurement position. For example, when measuring the AC mains, the measurement position is selected to be placed in the electric block. In this case, once the test pen touches the mains, it will instantly Can cause damage to the internal components of the multimeter. 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, so that no matter what parameter is mismeasured in the next measurement, it will not cause damage to the digital multimeter.
