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    testing mosfet

    I have 4 k3294 mos fets that test the same . Using an anolog meter on the 10k scale . with the neg probe on the source and pos on the drain. When I place my finger between the gate and the source the meter swicthes to a low reading which is typical but when I remove my finger the meter switches back to a low reading . Does mean that the device is bad ?

    #2
    Re: testing mosfet

    the way i do that test is

    put the DM into diode test and the pos to the drain and the neg to the source and should read open condition then i move the pos to the gate for an instant and the put it back to the drain without removing the neg from the source and the it should give some continuety and the if having that set up i touch the gate it should go back to open circuit. then do first steps again but instead of touching i switch the tips the red to the source and the black to the gate and then back as they were and it should go back to none. if that stuff gives the results mentioned then for me the mosfet is all good.

    maybe im all wrong but thats how i do it. hope it helps.

    peace.
    We don't have a great war in our generation, or a great depression, but we do, we have a great war of the spirit. We have a great revolution against the culture. The great depression is our lives. We have a spiritual depression.

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      #3
      Re: testing mosfet

      I test it this way. Set multimeter on ohms. Measure resistance "in circuit" between S-G, G-D, S-D. Any reading less than 30 ohms suggests it is shorted. If under 30 ohms, remove and retest out of circuit.
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        #4
        Re: testing mosfet

        but when I remove my finger the meter switches back to a low reading
        You mean it remains low? That might just be residual charge on the gate.

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          #5
          Re: testing mosfet

          I have a question about a MOSFET FQPF 27P06 (60V P-Channel) I just tested with two different Fluke meters.

          Fluke 1 showed:
          On = .2 ohms, Off = 336K A little low for off state??

          Fluke 2 showed:
          On = 886K , Off= 886K No change.

          Is this acceptable? (at least for the first fluke test)

          Do some lower voltage mosfets fail like this?
          The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

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