View source for Testing a MOSFET

[[File:RC EE MOSFET Pinout.png|thumb|350px|IRF9310 and IRF8734 Pinouts]]

= Testing a MOSFET =
'''If a MOSFET passes all 4 tests, it is likely a good device. If any of the tests are not satisfied, the part has been damaged.

''*Once the Gate is charged, it will remain charged for several minutes. Long enough to do the tests. You just have to be careful not to disturb the gate lead and accidentally discharge it.
''

== nFET ==

=== Test #1 - Turn nFET �off� and Test Gate-Source ===

Probe the ''Gate'' with the '''BLACK''' lead and the ''Source'' with the <span style="color:#FF0000">'''RED'''</span> lead. The reading should be an open circuit. Any other reading shows that there is a short between the Gate and Source. If it is shorted, no further testing is needed � it is damaged. This test will also turn off the device.

=== Test #2 - Test Drain-Source ===

Being turned off, the Drain-Source should be an open circuit. Test by probing with the '''BLACK''' lead on the ''Source'' and the <span style="color:#FF0000">'''RED'''</span> lead on the ''Drain''. The expected reading is an open circuit. The nFET has a reverse protection diode built in. To test this diode, reverse the polarity of the leads placing the <span style="color:#FF0000">'''RED'''</span> on the ''Source'' and the '''BLACK''' on the ''Drain''. The meter should read the forward voltage of the diode. If it shows as an open circuit, then the diode has been damaged.

=== Test #3 - Switch nFET �on� ===

Probe the ''Gate'' with the <span style="color:#FF0000">'''RED'''</span> lead and the ''Source'' with the '''BLACK''' lead. The expected reading is an open circuit. This double checks the Gate for short circuits and turns the device on.

=== Test #4 - Check Drain-Source junction for proper conduction ===

Make sure that you have not touched the Gate lead since you turned the device on. Probe with the <span style="color:#FF0000">'''RED'''</span> on the ''Drain'' and the '''BLACK''' on the ''Source''. The expected reading is a short circuit. Then probe with the polarity reversed with the <span style="color:#FF0000">'''RED'''</span> on the ''Source'' and the '''BLACK''' on the ''Drain''. This should also show a short circuit. If either of these shows an open circuit, then the Drain-Source is blown open.

== pFET ==

=== Test #1 - Turn pFET �off� and Test Gate-Source ===

Probe the ''Gate'' with the <span style="color:#FF0000">'''RED'''</span> lead and the ''Source'' with the '''BLACK''' lead. The reading should be an open circuit. Any other reading shows that there is a short between the Gate and Source. If it is shorted, no further testing is needed � it is damaged. This test will also turn off the device.

=== Test #2 - Test Drain-Source ===

Being turned off, the Drain-Source should be an open circuit. Test by probing with the <span style="color:#FF0000">'''RED'''</span> lead on the ''Source'' and the '''BLACK''' lead on the ''Drain''. The expected reading is an open circuit. The pFET has a reverse protection diode built in. To test this diode, reverse the polarity of the leads by placing the '''BLACK''' on the ''Source'' and the <span style="color:#FF0000">'''RED'''</span> on the ''Drain''. The meter should read the forward voltage of the diode. If is shows as an open circuit, then the diode has been damaged.

=== Test #3 - Switch pFET �on� ===

Probe the ''Gate'' with the '''BLACK''' lead and the ''Source'' with the <span style="color:#FF0000">'''RED'''</span> lead. The expected reading is an open circuit. This double checks the Gate for short circuits and turns the device on.

=== Test #4 - Check Drain-Source junction for proper conduction ===

Make sure that you have not touched the Gate lead since you turned the device on. Probe with the <span style="color:#FF0000">'''RED'''</span> on the ''Drain'' and the '''BLACK''' on the ''Source''. The expected reading is a short circuit. Then probe with the polarity reversed with the <span style="color:#FF0000">'''RED'''</span> on the ''Source'' and the '''BLACK''' on the ''Drain''. This should also show a short circuit. If either of these shows an open circuit, then the Drain-Source is blown open.