DIODE CHECKING ↓↓↓

Common diode

Zener diode

SMD diode

Checking diodes of any type generally uses  the same method except for high-voltage diode that commonly use in microwave oven (about 3KV to 5KV). To test a diode, you need to turn the  multimeter dial to diode test mode as shown in the image below.

Forward Direction

Probe the diode as shown in the photo.










Healthy Diode:
Forward direction should read 0.3V to 0.7V (multimeter beeps once ).
Reversing the probes you should get higher voltage reading >09.V or open (multimeter must not beep).

Shorted Diode:
When readings shows less than 0.3V in both directions (and multimeter continue beeping). If in the circuit, pull one leg to confirm the readings.

Open Diode:
When readings shows higher than 0.7V in both directions. Or both directions have the same readings. If in the circuit, pull one leg to confirm the readings.

High Voltage Diode Test:
High voltage diode cannot be checked by only multimeter. You need a DC power supply to check (15V), series resistor (to limit current), and your multimeter. Follow the connections as shown in the image below. This will determine the proper behavior of diode. Also refer below multimeter readings to check if the diode is good, short, or open.

 OPEN  the links below to help you learn diode types.




Types of diode (electronicshub)
Types of diode (instructables)
Types of diode (electronics-notes)