Generally speaking, when you receive a faulty Siemens inverter, before powering it on, you first need to use a multimeter to check the rectifier bridge and IGBT, whether the module is burnt, and whether there are obvious burn marks on the circuit board.

　　

(1) After power on, the panel displays [F231] or [F002] (MM3 frequency converter), and there are generally two possible causes of this fault. It is common for problems to occur with the power drive board, and a small portion may be caused by the main control board. You can try replacing the main control board first, otherwise the problem will definitely be with the power drive board.

　　

(2) After power on, there is no display on the panel (MM4 frequency converter), and the indicator light under the panel [green light not on, yellow light flashing]. This phenomenon indicates that the rectification and switching power supply are working normally, and the problem lies in one of the circuits of the switching power supply being abnormal.

　　

(3) Sometimes the display of [F0022, F0001, A0501] is uncertain (MM4), and it can work normally when tapping the chassis or moving the panel and motherboard. This is usually a problem with the connectors. Check the connectors in each part. It has also been found that some machines are caused by quality issues or poor soldering of resistance and capacitance components on the circuit board.

　　

(4) After power on, it displays [-------] (MM4), which is usually a problem with the main control board. In most cases, replacing the main control board can solve the problem, usually due to strong electrical interference in the peripheral control circuit causing damage to certain components of the main control board (such as chip capacitors, resistors, etc.). I analyze that it is also related to poor heat dissipation of the main control board. But there are also individual issues that arise on the power board.