There are many types of digital multimeters, and the scope of application is also very wide, but after all, multimeters are a kind of electronic products, and there may be some small problems in the process of use. Here are some small troubleshooting methods.
1. 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 starts to oscillate and the oscillation frequency is 40kHz. If the oscillator has no output, it means that the internal inverter of the TSC7106 is damaged, or the external components may be open. Observe that the waveform of the {21} foot of TSC7106 should be a 50Hz square wave, otherwise, the internal 200 frequency divider may be damaged.
2. Measure the parameters of the components.
For components within the fault range, perform on-line or off-line measurements, and analyze the parameter values. For on-line resistance measurement, the influence of components connected in parallel with it should be considered.
3. Hidden troubleshooting.
Recessive faults refer to the faults that appear and disappear from time to time, and the faults of the instrument are good and bad. This kind of fault is more complicated, and the common reasons include solder joints, loose, loose connectors, poor contact of the transfer switch, unstable component performance, and the lead will be broken continuously. 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, etc.
4. Visual inspection.
You can touch by hand whether the temperature rise of batteries, resistors, transistors, and integrated blocks is too high. If the newly installed battery is hot, the circuit may be shorted. In addition, the circuit should also be observed for disconnection, desoldering, mechanical damage, etc.
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.
