How to test the quality of the rectifier diode when there is a malfunction in the rectifier diode circuit?

First, remove all the rectifier diodes from the rectifier and use a multimeter of 100 × R or 1000 × Measure the two outgoing lines of the rectifier diode in the R ohm range (with the head and tail swapped once each).

If the resistance values measured twice differ significantly, such as those with high resistance values ranging from several hundred K Ω to infinity, and those with low resistance values ranging from only a few hundred Ω or even less, it indicates that the diode is good (except for diodes with soft breakdown). If the resistance values measured twice are almost equal and the resistance values are very small, it indicates that the diode has been broken down and cannot be used. If the resistance values measured twice are both infinite, it indicates that the diode has been internally disconnected and cannot be used.