The method of measuring the quality of rectifier diode with pointer multimeter
pointer multimeter
Pointer multimeter to detect whether the rectifier diode is good or bad
Diodes have unidirectional conductivity. That is, the forward voltage is applied to conduct, and the reverse voltage is applied to cut off. Its forward resistance is small and reverse resistance is large, which is the basis for detection.
1. Under normal circumstances, for a single rectifier diode, first place the multimeter in the Rx100 or Rx1K range of the ohm range when testing. Connect the two test leads to the two leads of the diode to 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 primary resistance is large and the primary resistance is small, it means that the rectifier diode is normal. If the resistance is small, the black test lead is connected to the positive pole of the diode, and the red test lead is connected to the negative pole of the diode.
If the two resistance values are large, it means that the diode is open circuit.
If the two resistance values are very small, it means that the diode is short circuited.
It should be noted that the measured resistance value will be different when different gears are selected.
2. During actual maintenance, it is often necessary to solder the diode from the circuit, which is troublesome. In fact, it is also possible to directly detect online without soldering the rectifier diode. The method is simple and the effect is good. Now share it for reference.
Power on the electrical equipment normally (alternating current), turn the multimeter to the AC voltage range, select the specific gear according to the rectification voltage range, connect the red test lead to the positive pole of the rectifier diode, and the black test lead to the negative pole to measure an AC voltage value. Then reverse the test leads, and measure a voltage value. In the same way, set the range of the multimeter to the DC voltage range and measure a DC voltage value. Then compare the results.
If the AC voltage value measured for the first time is about twice the DC voltage value, and the AC voltage measured for the second time is zero, it means that the rectifier diode is normal.
If the two measured AC voltage values are not much different, it means that the diode has broken down.
If the voltage value measured twice is zero, it means that the diode has been short-circuited.
If the value measured for the second time is neither zero nor equal to the value of the first time, it means that the performance of the diode has deteriorated.
