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Lenovo M920Q - dead (my fault)

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    Lenovo M920Q - dead (my fault)

    So yesterday I was looking for a help because of "black screen" issue after BIOS flash.

    I was testing different BIOS/EC dumps found on the Internet, and I've made a big mistake..

    After flashing bios & ec - I've plugged mainboard only (with attached radiator) to the power adapter, and after a 1 second saw a smoke coming from motherboard.

    Quickly disconnected power-supply and then I saw tweezers touching PCIE bottom pins

    The smoke came from burned N-MOSFET PQ809 (SM2404NSANC), replaced it with greater NX7002AK N-MOSFET but no luck, board is still dead.

    DC-IN is getting 20V so power adapter is working fine.
    F2 and F10 fuses are okay.

    PQ809 measures:
    G 8.3V
    S 2.9V
    D 3.3V

    COIL PL702 0V (0.01V when measuring in diode mode to ground)
    COIL PL1001 0V
    COIL PL1002 1V
    COIL PL803 5V
    COIL PL804 3.3V
    PL902 0V

    COILS near cpu socket 0V

    Is this repairable? What to measure next?

    MOD Edit: Link to Schematic & Boardview https://www.badcaps.net/forum/showthread.php?t=122154
    .
    Last edited by SMDFlea; 08-10-2023, 03:46 AM.

    #2
    Re: Lenovo M920Q - dead (my fault)

    Checked all pcie pins and no short found.
    PCI-E is not getting +12V
    Last edited by meciu; 08-10-2023, 12:48 PM.

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      #3
      Re: Lenovo M920Q - dead (my fault)

      3V3_S5 line gets 2.9V instead of 3.3V and I don't know why.. any tips?

      Comment


        #4
        Re: Lenovo M920Q - dead (my fault)

        follow the mosfet gate pin - see what drives it

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          #5
          Got the same problem like you, there you able to fix it?
          Currently waiting for replacement of the burned transistor.
          I will provide feedback if it worked or not.

          Currently my Measurements are the following(with burned transistor)
          Click image for larger version

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