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Macbook pro A1278 no power with led green on magsafe

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    Macbook pro A1278 no power with led green on magsafe

    Hi!
    this is my first macbook and i'm trying to repair it.
    I have read many posts but they can't solve my problem.

    on the mainboard there isn't any burnt component and the main fuse is ok.

    in the picture you can see my first measures near the main connector.
    Hope someone helps me
    Attached Files

    #2
    Re: Macbook pro A1278 no power with led green on magsafe

    post picture of the other side.

    and post voltage on the 2 spot ive marked.
    Attached Files

    Comment


      #3
      Re: Macbook pro A1278 no power with led green on magsafe

      thanks for your reply
      Attached Files

      Comment


        #4
        Re: Macbook pro A1278 no power with led green on magsafe

        here others measurement
        Attached Files

        Comment


          #5
          Re: Macbook pro A1278 no power with led green on magsafe

          here others
          Attached Files

          Comment


            #6
            Re: Macbook pro A1278 no power with led green on magsafe

            making measure all around the board without a logic is no sense. this big thing with all 0 volt is lan filter..... useless to measure for now.

            i asked for 2 measure on these 2 coils (inductor) in my previous post.

            next report voltage on green zone.

            total 2 measure+ 1 ground.

            u should have on green spot (white fuse) 12.5 volt ;
            3.42 on the other green marked area.

            if u have 3.3 volt on coil, u have 12.5 volt on that green marked fuse, and if u have 3.35 or higher (not over 3.42) u can put a fan, some ram slot, lvds connector with lcd and short that circled 2 dot on mainboard with a wtezer (smc bypass) and see if macbook start normally.

            before all that, make sure u understand that procedure right. shorting those 2 pins should make your macbook start, so put fan, ram ecc ecc and be carefull to not short anything else. put all component on a non conductive zone.

            u can try with magsafe only,with battery only , and with both.

            any throuble, ask before act.
            Attached Files
            Last edited by dellxps15; 02-23-2015, 07:12 AM.

            Comment


              #7
              Re: Macbook pro A1278 no power with led green on magsafe

              in the green marked zone i have 12.5, the same voltage on the near white fuse

              Comment


                #8
                Re: Macbook pro A1278 no power with led green on magsafe

                there are 2 green marked zone.. one left (white fuse) one circled green with short write. post voltage on those 2 pads. one is ground so no voltage, but the other should have voltage around 3.42volt.

                Comment


                  #9
                  Re: Macbook pro A1278 no power with led green on magsafe

                  ok
                  Attached Files

                  Comment


                    #10
                    Re: Macbook pro A1278 no power with led green on magsafe

                    follow procedure of smc bypass by shorting green circled mark (3.45volt and gnd) with ram and fan connected and report if macbook start.

                    Comment


                      #11
                      Re: Macbook pro A1278 no power with led green on magsafe

                      it doesn't start...

                      Comment


                        #12
                        Re: Macbook pro A1278 no power with led green on magsafe

                        report voltage in marked green coil (inductor)

                        suspect u misisng 3.3 volt as bios doesnt have 3.3 volt.
                        Attached Files

                        Comment


                          #13
                          Re: Macbook pro A1278 no power with led green on magsafe

                          there are 3.3 volts on that coil

                          Comment


                            #14
                            Re: Macbook pro A1278 no power with led green on magsafe

                            down the arrow there is bios chip. post voltage.

                            (the other one in first picture was lan chip)
                            Attached Files

                            Comment


                              #15
                              Re: Macbook pro A1278 no power with led green on magsafe

                              0 volts on every pin of bios chip

                              Comment


                                #16
                                Re: Macbook pro A1278 no power with led green on magsafe

                                voltage on these 2 component and those 2 resistors ?

                                all marked with circle green
                                Attached Files

                                Comment


                                  #17
                                  Re: Macbook pro A1278 no power with led green on magsafe

                                  ok
                                  Attached Files

                                  Comment


                                    #18
                                    Re: Macbook pro A1278 no power with led green on magsafe

                                    someone already put hands on this board i think

                                    missing component marked with green circle.

                                    code: u7740

                                    component: TPS720105
                                    Attached Files
                                    Last edited by dellxps15; 02-23-2015, 11:50 AM.

                                    Comment


                                      #19
                                      Re: Macbook pro A1278 no power with led green on magsafe

                                      as you can see in this picture, that chip in not present on the same motherboard...
                                      Attached Files

                                      Comment


                                        #20
                                        Re: Macbook pro A1278 no power with led green on magsafe

                                        on my schematic it was not mentioned "no staff" .... weird apple


                                        report voltage on that chip.
                                        also in the near resistor.

                                        also normal and while shorting the 2 spot i mentioned before (3.45 and gnd)
                                        Attached Files

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