For faulty instruments, maintenance personnel should be required to check them according to the instructions, which generally include the working principle, use function and precautions of electronic instruments, as well as some simple troubleshooting methods. After fault judgment, it is necessary to check the fault records of instrument users to find out the cause of the fault. Because there are many fault detection methods of electronic instruments, maintenance personnel usually use multimeter to check, which has the performance of rapid inspection. However, due to the complex structure of instruments and meters, in the initial inspection of fault detection, simple, quick and intuitive methods should be used to detect whether the solder joint is burned, whether the electronic circuit is short-circuited, whether the electrolytic capacitor leaks liquid, etc. Because some faults need to be connected to the power supply and can only be observed after measurement, such as incomplete display, sparks in the circuit and silence when electronic instruments are replaced. Therefore, after turning on the power supply and starting the instrument, we should first carefully observe the fault phenomenon of the electronic instrument, check and record the various functions and states of the instrument, and provide reference for the next work.