Rectifier diodes are mainly used in rectifier circuits to convert alternating current into direct current by using the unidirectional nature of the diode. The rectification forms include half-wave rectification and full-wave rectification.

Normally, for a single rectifier diode, first set the multimeter to the Rx100 or Rx1K ohm range when testing. Connect the two test leads to the two leads of the diode and measure the resistance value. Then exchange the two test leads and measure the resistance value again. Finally, compare the results of the two measurements.

If the resistance is very small both times, it means the diode is short-circuited.

If the voltage value measured twice is zero, it means that the diode is short-circuited.