How to detect the rectifier diode

As a semiconductor device, a rectifier diode has a unidirectional conduction property. Therefore, we can determine the electrode of the diode by detecting the positive and negative resistance values with a multimeter, and can also estimate whether the diode is damaged. The specific rectifier diode detection method is as follows:

1. Polarity discrimination: Place the multimeter in R×100 or R×1k. The two pens are connected to the two electrodes of the diode. After measuring one result, adjust the two test leads and measure one result. Of the results of the two measurements, one measured a larger value (which is a reverse resistance) and one measured a smaller value (which is a forward resistance). In a measurement with a small resistance value, the black meter is connected to the anode of the diode, and the red meter is connected to the cathode of the diode.

2. The detection of single negative conductivity and the judgment of good or bad: Generally, the forward resistance of the material diode is about 1kΩ, and the reverse resistance is about 300. The silicon material diode has a resistance value of about 5 kΩ and a reverse resistance value of ∞ (infinity). The smaller the forward resistance, the better, and the larger the reverse resistance, the better. The difference between the positive and negative resistance values is different, indicating that the unidirectional conduction characteristics of the diode are better. If the measured forward and reverse resistance values of the diode are close to 0 or the resistance is small, it indicates that the diode has a breakdown short circuit or leakage damage. If the measured forward and reverse resistance values of the diode are infinite, the diode is open circuit damaged.

3. Detection of reverse breakdown voltage: The reverse breakdown voltage of the diode (withstand voltage) can be measured with the transistor DC parameter test chart. The method is as follows: when measuring the diode, the "NPN/PNP" selection button of the test table should be set to the NPN state, and then the positive pole of the diode to be tested is connected to the "C" socket of the test table, and the negative pole is inserted into the "e" of the test table. "The jack, then press the "V (BR)" button, the test meter will indicate the reverse breakdown voltage of the diode. The megohmmeter and multimeter can also be used to measure the reverse breakdown voltage of the diode. When measuring, the negative pole of the diode to be measured is connected with the positive pole of the megger. The positive pole of the diode is connected to the negative pole of the megohmmeter, and the multimeter is used. Monitor the voltage across the diode for a suitable DC voltage range.