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Asus x751lk - first repair attempt

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    Asus x751lk - first repair attempt

    Hello,

    I am trying to do my first repair. I have motherboard of asus x751lk rev 2.0

    When I plug in the charger computer turns on, fan spins, but there is no image on the lcd or hdmi/vga output. Also the cpu and gpu are getting warm.

    I have this area where is something is shorted to ground.
    every other contact is shorted (some marked on the picture with squares) and it gives about 0.9v while on not shorted pins I get 19 v.


    I would like to have some advice on how to proceed.

    Thanks

    #2
    Re: Asus x751lk - first repair attempt

    please stop repairing and give it to someone that have some skill and knowledge.

    what u see is mostly CPU power circuit. and 0.9V is absolutely ok, it is not shorted. if it was shorted the main power rail will be turned off

    dont proceed further because u dont have basic knowledge of this

    u must as first learn basics to be able to understand what is going on in this circuit

    Comment


      #3
      Re: Asus x751lk - first repair attempt

      Originally posted by ktmmotocross View Post
      please stop repairing and give it to someone that have some skill and knowledge.

      what u see is mostly CPU power circuit. and 0.9V is absolutely ok, it is not shorted. if it was shorted the main power rail will be turned off

      dont proceed further because u dont have basic knowledge of this

      u must as first learn basics to be able to understand what is going on in this circuit
      well I am just trying to learn

      Looks like I am not on the right forum. Mods you can close this topic.

      thanks for your help anyway.

      Comment


        #4
        Re: Asus x751lk - first repair attempt

        if u want to learn u must start with basics to be able to understand how it works

        Comment


          #5
          Re: Asus x751lk - first repair attempt

          The problem could be the bios ,do you have a bios programmer .
          All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

          Comment


            #6
            Re: Asus x751lk - first repair attempt

            Originally posted by SMDFlea View Post
            The problem could be the bios ,do you have a bios programmer .
            I agree with SMDFlea most likely BIOS issue check all the Big Gray Coils for Voltage and tell us what’s missing, try to find basic knowledge of how SMD component working & testing@ how to used multimeter
            Last edited by Techtiger; 03-30-2019, 01:26 PM.

            Comment


              #7
              Re: Asus x751lk - first repair attempt

              Could be faulty RAM too. Or just need to reset them in place.

              Comment


                #8
                Re: Asus x751lk - first repair attempt

                Originally posted by techtiger View Post
                I agree with SMDFlea most likely BIOS issue check all the Big Gray Coils for Voltage and tell us what's missing, try to find basic knowledge of how SMD component working & testing@ how to used multimeter
                Hello,

                I have checked all the coils and all the voltages seems to be present
                1.4 around the disk port
                0.9 2-coils around the nvidia gpu
                1.7 around the cpu
                3.3
                5.0

                bios chip has 3.3 (if that matters) at pin 1,2,3,7 and 8 when the computer is on.

                I have tried with and without the ram (it has 1 stick and 8 pads soldered directly on the motherboard.

                Comment


                  #9
                  Re: Asus x751lk - first repair attempt

                  Originally posted by ktmmotocross View Post
                  if u want to learn u must start with basics to be able to understand how it works
                  any suggestion where to start?

                  Comment


                    #10
                    Re: Asus x751lk - first repair attempt

                    Originally posted by SMDFlea View Post
                    The problem could be the bios ,do you have a bios programmer .
                    Not yet, but I'm looking to get one from ebay

                    Comment


                      #11
                      Re: Asus x751lk - first repair attempt

                      Originally posted by alloallo View Post
                      any suggestion where to start?
                      what gpu u have in it?

                      Comment


                        #12
                        Re: Asus x751lk - first repair attempt

                        It has GTX 870M N15P-GT-A2 (soldered to the motherboard)

                        Comment


                          #13
                          Re: Asus x751lk - first repair attempt

                          that can be problem. if u have allpwrgd signal


                          but with that great laptop i dont recommend u to repairing it for yourself. better give it to good service where is able to reball GPUs. they do diagnose and if it is in GPU they can reball it
                          Last edited by ktmmotocross; 03-31-2019, 06:22 AM.

                          Comment


                            #14
                            Re: Asus x751lk - first repair attempt

                            Originally posted by ktmmotocross View Post
                            that can be problem. if u have allpwrgd signal


                            but with that great laptop i dont recommend u to repairing it for yourself. better give it to good service where is able to reball GPUs. they do diagnose and if it is in GPU they can reball it
                            OK.. I will try to get someone who will reball the chip for me.

                            Will post the results here.

                            Comment


                              #15
                              Re: Asus x751lk - first repair attempt

                              Flash a new bios first, rule out the easiest things .
                              All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

                              Comment


                                #16
                                Re: Asus x751lk - first repair attempt

                                Originally posted by SMDFlea View Post
                                Flash a new bios first, rule out the easiest things .
                                any suggestion for bios programmer?

                                Ebay has unlimited options available

                                Comment


                                  #17
                                  Re: Asus x751lk - first repair attempt

                                  cheapest CH341A will be enough, but check if u have 3 or 1.8V bios chip and if u have 1.8V buy it with adapter for 1.8V

                                  on ali is about 2euros

                                  and offcourse u will need solder iron or beter hotair station
                                  Last edited by ktmmotocross; 03-31-2019, 11:01 AM.

                                  Comment


                                    #18
                                    Re: Asus x751lk - first repair attempt

                                    Originally posted by alloallo View Post
                                    Hello,

                                    I have checked all the coils and all the voltages seems to be present
                                    1.4 around the disk port
                                    0.9 2-coils around the nvidia gpu
                                    1.7 around the cpu
                                    3.3
                                    5.0

                                    bios chip has 3.3 (if that matters) at pin 1,2,3,7 and 8 when the computer is on.

                                    I have tried with and without the ram (it has 1 stick and 8 pads soldered directly on the motherboard.
                                    test this points , what is the SIO IC ITEXXXX any one have the Schematic for this Mob,try to flach bios
                                    Attached Files
                                    Last edited by Techtiger; 03-31-2019, 01:13 PM.

                                    Comment


                                      #19
                                      Re: Asus x751lk - first repair attempt

                                      Schematics attached

                                      SIO IT8585E

                                      I have measured the point you wanted. All the volts are as you wrote.

                                      the most top coil in the yellow is 16.8v

                                      voltage on smaller caps at rams are 0.7v. At the biger ones there is 1.4v
                                      Attached Files

                                      Comment


                                        #20
                                        Re: Asus x751lk - first repair attempt

                                        I agrre with @smdflea. It seems like bios issue.

                                        Comment

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