How to use digital multimeter to check the line fault point
1. Appearance inspection.
You can touch whether the temperature rise of batteries, resistors, transistors and integrated blocks is too high by hand. If the newly installed battery is hot, the circuit may be short-circuited. In addition, you should also observe whether the circuit is broken, soldered, mechanically damaged, etc.
2. Waveform analysis.
Observe the voltage waveform, amplitude, period (frequency) of each key point of the circuit with an electronic oscilloscope.
For example, if the clock oscillator starts to vibrate, if the oscillator has no output, it means that the internal inverter is damaged or the external component is open.
3. Measure the component parameters.
For the components within the fault range, online measurement or offline measurement shall be conducted, and the parameter values shall be analyzed. When measuring the resistance online, the influence of the components connected in parallel should be considered.
4. Hidden troubleshooting.
Implicit fault refers to the fault when the fault is hidden, and the instrument is good or bad. This kind of fault is complicated, and the common reasons include virtual welding of solder joints, loosening of connectors, poor contact of transfer switch, 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 the working voltage at all levels.
Detect the working voltage of each point and compare it with the normal value.
First of all, we should ensure the accuracy of the reference voltage, and it is best to use a digital multimeter of the same model or similar to measure and compare.
How to detect the fault of lighting circuit with multimeter
If the wire is too long, it is difficult to measure.
(1) hit the multimeter to the AC voltage range of 750v, and connect the red and black probes to the zero line respectively for testing. Pay attention to catch it well, wait for a few seconds, and read it after the data is stable.
② Non-contact inductive acousto-optic measuring pen can be purchased online, which is safe, has sound and light prompts and is not expensive. A more expensive digital multimeter also has this function.
