How to Test MOSFET( Find bad MOSFET )

Introduction:

• The MOSFET (Metal Oxide Semiconductor Field Effect Transistor) transistor is a semiconductor device which is widely used for switching and amplifying electronic signals in the electronic devices.
• The MOSFET is a four terminal device with source(S), gate (G), drain (D) and body (B) terminals. The body of the MOSFET is frequently connected to the source terminal so making it a three terminal device like field effect transistor.
• Below are the guides on how to know if MOSFET is defective. These are the most common techniques that can be used to check if MOSFET is defective.

method #1:

A

• First turn ON digital multimeter and select continuity mode.
• Connect the test leads to the MOSFET terminals. Keep test leads connected for a few seconds at like this (A) connection.
• if multimeter buzzer is ON, the MOSFET is bad(damage) conditions.

B

• Connect the test leads to the MOSFET terminals. Keep test leads connected for a few seconds at like this (B) connection. 
• if multimeter buzzer is OFF, the MOSFET is good conditions.

 

method #2:

N-Channel MOSFET :

C

• After the connection(C) is complete, when you press the switch(LED ON Switch) - if LED is ON, the IGBT is good. else,  LED is OFF, the IGBT is bad.
• when you press the switch(LED OFF Switch) - if LED is OFF, the IGBT is good. else, the IGBT is bad.

P-Channel MOSFET :

E

• After the connection(E) is complete, when you press the switch(LED ON Switch) - if LED is OFF, the IGBT is good. else,  LED is ON, the IGBT is bad.
• when you press the switch(LED OFF Switch) - if LED is ON, the IGBT is good. else, the IGBT is bad.