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.

3. Measure the component parameters.

4. Hidden troubleshooting.

5, detect the working voltage at all levels.

(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.