Zener Diode Test
If you want check a zener diode is whether it's good or defective , there are two simple but effective quick
you can do.
Test a Zener Diode with an Ohmmeter of a Multimeter
A very good test you can do is to check a zener diode with your multimeter set to the setting
This is a simple test we can do is to check whether is good , opne or shorted.
So we take the ohmmeter and place it across the leads of the diode, the orientation is very important.
Anode -Cathode Diode Resistance TEST
We first take the ohmmeter and place the positive probe on the anode of the diode , the diode
and the negative probe on the cathode of the diode the diode should read a moderately low
resistance, maybe a few hundred thousand of ohms .
Cathode-Anode Diode Resistance Test
Now take the ohmmeter and switch the probes around so that the probe of the multimeter is now on the
cathode of the diode and the negative lead on the anode. In this the diode should read a much higher resistance , well over 1MΩ.
A typical reading may for example , be 2.3MΩ. The multimeter may even indicate 'OL' for an open circuit,
since the resistance is so high.
If you read a moderately low resistance with the zener diode one way and a high resistance with the leads
the other, this is sign that the zener diode is good. A zener diode should read relatively low resistance in the
forward biased direction and very high resistance in the reverse biased direction.
Open Diode
If a zener diode reads low resistance in both directions, this is a sign that the diode is open. A diode should not measure very high resistance in the forward biased direction.The diode should be replaced in the circuit.
Shorted Diode
If the zener diode reads low resistance in the both direction, this is a sign that the diode is shorte. A diode should not measure low resistance in the reverse biased direction. The diode should be replaced in the circurit.
