Troubleshooting of hidden faults in digital multimeters
There are many types of digital multimeter, the scope of application is also very wide, but after all, the multimeter belongs to a kind of electronic products, perhaps in the process of using some small problems, here to share a few points of troubleshooting small methods.
1, waveform analysis.
With an electronic oscilloscope to observe the circuit at all key points of the voltage waveform, amplitude, period (frequency) and so on. For example, such as measuring whether the clock oscillator vibration, oscillation frequency is 40 kHz. if the oscillator has no output, the TSC7106 internal inverter is damaged, may also be an external component open circuit. Observe TSC7106 foot {21} waveform should be 50Hz square wave, otherwise, it may be the internal 200 frequency divider damage.
2, measuring component parameters.
For components within the scope of the fault, online measurement or offline measurement, parameter values should be analysed. For resistance online measurement, should consider the impact of the components connected in parallel with it.
3, hidden troubleshooting.
Hidden fault refers to the fault is hidden, the instrument is sometimes good and sometimes bad fault. Such failures are more complex, common causes include solder joints, loose, loose connectors, poor contact with the transfer switch, component performance is unstable, the lead will be broken and so on. In addition, also includes some external factors caused by. Such as high ambient temperature, excessive humidity or intermittent strong interference signals nearby and so on.
4, appearance check.
You can touch the battery, resistor, transistor, integrated block temperature rise is too high. If the newly loaded battery is hot, indicating that the circuit may be short-circuited. In addition, should also observe whether the circuit is broken, desoldering, mechanical damage.
5, test the working voltage at all levels.
Detect the operating voltage at various points, and compare with the normal value, first of all, should ensure the accuracy of the reference voltage, it is best to use a piece of the same model or similar digital multimeter for measurement and comparison.
