Common troubleshooting instructions for multimeters
A digital multimeter, also known as a multimeter, multimeter, multimeter or three-purpose meter, is a multi-purpose electronic measuring instrument that generally includes ammeter, voltmeter, ohmmeter and other functions. Compared with pointer multimeters, digital multimeters have the advantages of high precision, fast speed, large input impedance, digital display, accurate readings, strong anti-interference ability, and high degree of measurement automation, and are widely used. However, if used improperly, it may cause malfunction.
Digital multimeter troubleshooting should generally start with the power supply. Digital multimeter troubleshooting can generally be carried out as follows.
1. Appearance inspection.
You can touch the battery, resistor, transistor, and integrated block with your hands to see if the temperature rise is too high. If a newly installed battery becomes hot, 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 in the circuit. For example, if you test whether the clock oscillator is starting to oscillate, if the oscillator has no output, it means that the internal inverter is damaged, or the external component may be open circuited.
3. Measure 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 fault refers to the fault that appears and disappears, and the instrument is good and bad sometimes. This type of failure is relatively complex, and common causes include weak solder joints, loose joints, loose connectors, poor contact of the transfer switch, unstable component performance, and continuous breakage of leads. In addition, it also includes some external factors. Such as the ambient temperature is too high, the humidity is too high or there are intermittent strong interference signals nearby, etc.
5. Detect the working voltage at all levels.
To detect the working voltage at each point and compare it with the normal value, you should first ensure the accuracy of the reference voltage. It is best to use a digital multimeter of the same model or a similar one for measurement and comparison.
In addition to the above possible reasons, the damage to the digital multimeter may also be caused by the wrong measurement gear. For example, when measuring AC mains power, the measurement gear is placed in the electrical barrier. In this case, once the test leads contact the mains power, the meter will instantly It may cause damage to the internal components of the multimeter. Therefore, before using a multimeter to measure, be sure to check whether the measurement gear is correct. After use, set the measurement selection to AC 750V or DC 1000V, so that no matter what parameters are mismeasured during the next measurement, the digital multimeter will not be damaged.
