To test a MOSFET, touch the negative probe of a multimeter to the "source" of the MOSFET and the positive probe to the "gate" and then to the "drain," then touch a finger between the source and the gate and see if the multimeter reading rises. If the reading rises, then the MOSFET works properly.Continue Reading
A MOSFET is a metal-oxide-semiconductor field-effect transistor. It is a four-terminal device that is used to switch electronic signals. The following is an easy test to determine if a MOSFET is working properly.
While holding the MOSFET by the plastic case and not touching any of the metal components, connect the negative probe of a multimeter to the MOSFET's "source" terminal.
Touch the positive probe of the multimeter to the MOSFET's gate, and then connect it to the drain. This should send just enough current through the MOSFET to turn it on.
At this point, the multimeter should have a very low reading. Place a finger such that it touches both the source and gate terminals of the MOSFET. If the reading on the multimeter spikes up to a higher number, then the MOSFET is working properly.