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basic mosfet question

Discussion in 'Electronic Basics' started by [email protected], Jul 31, 2006.

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  1. Guest

    hello,

    I was wondering how much voltage should we measure in the gate of a
    P-channel power MOSFET. I ask this because I am trying to repair a
    Philips monitor. I found out that the B+ going to the collector of HOT
    connected on the drain of a power MOSFET (IRF 9620). The low voltage
    power supply works fine. I can measure dc voltage on the source
    terminal of the MOSFET but there is no voltage present on the drain. So
    there is no HOT collector voltage. Now measure the gate dc voltage and
    the dc gate voltage I think is too high (same voltage as with the
    source). Gate is connected through a crystal diode and a 22k resistor.
    Are these passive components do not provide any voltage drop to the
    gate? Can anyone give me some explanation about this and how P-channel
    mosfet works in general. Also what is gate drive?

    thanks in advance for explanation and patience.


    ian
     
  2. Eeyore

    Eeyore Guest

    HOT ?????

    Graham
     

  3. Think real hard about it. A collector, B+ and a monitor.





















































    Horizontal Output Transistor
    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  4. Chris

    Chris Guest

    Hi, Ian. Try sci.electronics.repair , and be sure to include the model
    number of the monitor.

    I'm sure you'll get a bit of good advice there.

    Good luck
    Chris
     
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