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Asus GL752V Blowing new MOSFETS

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    Asus GL752V Blowing new MOSFETS

    Hello All I wonder if anyone can help me,

    I'm trying to fix an Asus GL752V.
    The laptop turned on with only the BATT/PW LED's showing on the front, no display/POST.
    I found that a MOSFET near the top left side of the SSD bay had blown rather aggressively, (black skid mark see pics) I removed the blown MOSFET and tested the one to the left of it, also blown (short on all pins), I tested board for shorts after the removal all seemed ok.
    I replaced both MOSFETS and did a short circuit test all still good (well low resistance on right FET from GtoS red flag?)

    I powered on the laptop without memory and the PW LED came on, so I thought all was good, I then installed a memory module turned on again and no power no lights, checked FET's and found both to be shorted AGAIN!

    Please could someone guide me to a solution.

    PS. I found on power connect (not pushing the power button) after the FET replacement the southbridge was warm, I'm guessing this is not normal and I think its the death knell of this laptop, Is it worth continuing with it?

    Any advice suggestion.
    Thanks.
    Attached Files

    #2
    Re: Asus GL752V Blowing new MOSFETS

    Is the silkscreened motherboard part number GL752VW REV 2.1
    All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

    Comment


      #3
      Re: Asus GL752V Blowing new MOSFETS

      sometimes resistors go high and also ceramic caps are known to go short . either might be your problem

      Comment


        #4
        Re: Asus GL752V Blowing new MOSFETS

        Posting some details from the boardview for this logic board.
        Attached Files

        Comment


          #5
          Re: Asus GL752V Blowing new MOSFETS

          replace ic and mosfets

          Comment


            #6
            Re: Asus GL752V Blowing new MOSFETS

            Hello SMDFlea,

            Yep that is the exact one.

            Comment


              #7
              Re: Asus GL752V Blowing new MOSFETS

              Hello petehall347,

              I did check nearby caps, and used voltage injection (1.2v max) at the stated site, however I didn't find any shorted caps and I'm unsure of the values of the resistors as I have no board info, there is a resistor connecting GtoS on the original blown FET I believe it is very low resistance.

              All that said, I need to remove the blown FET's and recheck the board as things may have changed since the FET's blow.

              Comment


                #8
                Re: Asus GL752V Blowing new MOSFETS

                Hello mon2,

                Thanks for the pictures, however I dont have any frame of reference for the given pics, I dont know the location or what the components are.

                Comment


                  #9
                  Re: Asus GL752V Blowing new MOSFETS

                  Hello ktmmotocross,

                  Are you talking about the southbridge I mentioned, or the IC near the blown FET?
                  Is it a FET driver or a buck controller?

                  Comment


                    #10
                    Re: Asus GL752V Blowing new MOSFETS

                    Originally posted by mon2 View Post
                    Posting some details from the boardview for this logic board.
                    Sorry mon2 I had my "stupid" glasses on, I see what it is thanks.

                    Comment


                      #11
                      Re: Asus GL752V Blowing new MOSFETS

                      Originally posted by BlkMolly View Post
                      Hello ktmmotocross,

                      Are you talking about the southbridge I mentioned, or the IC near the blown FET?
                      Is it a FET driver or a buck controller?
                      FET is driven by controller. so u can tell it is FET controller or buck controller.

                      replace controller ic with all mosfets, but offcourse first check for shorts before and after install, to be sure
                      Last edited by ktmmotocross; 10-24-2021, 04:47 AM.

                      Comment


                        #12
                        Re: Asus GL752V Blowing new MOSFETS

                        Hello Guys,
                        I have done some more digging and found this (see pic attached) DDR PSU controller

                        I guess for some reason the two FET where energized at the same time resulting in massive current passing through them so BOOM!

                        I would like to know why so I may put a scope on the controller and view the high and low gate drivers (maybe just a meter in continuity will work to see if there is a short?)

                        Am I on the right path and is there anything else I should consider?

                        Anyway thanks to all for there input and ktmmotocross for suggesting the controller.

                        PS I wonder if my memory module is ok, if it got hit with 19v I doubt it.
                        Is there a way of testing it without putting another laptop in danger?
                        Attached Files

                        Comment


                          #13
                          Re: Asus GL752V Blowing new MOSFETS

                          Anybody know the value of PR8604 in attached picture, I'm thinking it might be about 10k?

                          Many thanks.
                          Attached Files

                          Comment


                            #14
                            Re: Asus GL752V Blowing new MOSFETS

                            Bad news about this one, I found the CPU has a short on the 1.2v rail :-(

                            Thanks for all the help.

                            Comment

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