Taking over a 15kW WEICHI frequency inverter, it was damaged by lightning strikes. The motherboard and driver board were both struck by lightning, but fortunately, the module and CPU were not damaged.
Inspection:
- Control terminal+10V voltage to 0, no output. This voltage is obtained by stabilizing the+15V of the switching power supply through the LM317 (eight pin SMT IC) circuit. At the moment, there is no LM317 SMT IC at hand, so a 100 Ω resistor and a 10V voltage regulator are used as substitutes for repair;
- The LF347 chip IC (four operational amplifier integrated circuit) in the voltage detection circuit is damaged, and the LM324 chip is directly used as a substitute. The functions of each pin are consistent;
- The SMT transistor for controlling the charging relay is damaged and replaced with a plastic sealed direct insertion transistor D887.
All lightning faults have been repaired. The test run is normal.