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Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

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    Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

    Hello, thanks for reading this!

    I have a macbook pro mid 2012 13 inch that is completely dead, magsafe charger plugged in- sometimes green light, sometimes nothing. I purchased this computer already broken, the person said (they often lie, but I believe him) that he tried to upgrade the HDD himself and when he put it together, the computer was dead.

    The board is very clean, no water damage (I have worked on hundreds of water damaged boards, so I believe I am quite good at spotting the tiniest corrosion) This leads me to believe that he shorted something when working on it, prob with his screwdriver.

    The battery is completely shot, I put it in a working pro and it does not charge, it only has 0.15V on it, which again leads me to believe that it was shorted. I even took this board and put it in my working late 2011, no life, and vice versa (put the working 2011 board in this computer, everything was working but it was slow as hell- I believe this is because the temp sensors are not cross-compatible)

    What I know:
    The board has 2 fuses on it, one of which is on the magsafe port (I changed the whole magsafe port, so that is not it). But I found some conflicting information as to where the main fuse is. Most of the threads are on older macbooks, so they may not necessarily apply.

    The battery is good (i put in a new, working battery)
    My charger is good
    The magsafe DC board is good

    What I do not know:
    how to read the schematics (sorry)
    how to diagnose the board properly
    what to do next?

    I tried to check some parts that I suspect are the fuse with my multimeter continuity function, I attached a picture with a board and what I measured. These are based on previous threads about older macbooks.

    On pics:
    no 1: OK (multimeter goes to 0)
    2:OK
    3:No reaction (Multimeter stays at 1)
    4: OK
    5: OK

    These are based on some info from the net, some say the fuse is (was) near the display cable, some say it is down near the battery plug, or on the other side next to where magsafe DC plugs in.

    To make this slightly more interesting and maybe to motivate people to help even a noob like myself, I decided to add a little twist: If you help me and we do get the board working, I will donate $100 to a charity or nonprofit of your choosing.

    I was going to take the computer to an Apple store for diagnostics, but I would prefer to fix it myself. (out of warranty)
    Attached Files

    #2
    Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

    main fuse for ac dc is N°4 on your picture. number 1 is for battery. 2-3 are not fuse.

    plug-in magsafe without battery and see if at fuse 4 u have 16-18.5 volt both side. if yes then check isl6259 U7000 pin N°3 if 16-18v are present.

    Comment


      #3
      Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

      Hi, thanks for your reply, I really appreciate it! I will measure the fuse when I get home, but just to speed things up, I have no idea what is isl6259 U7000 pin N°3 or how to find it, it's probably a retarded question, sorry. Can you explain in a simpleton-friendly way how to measure it? I mean even if I find the pin, what do I measure the voltage against (eg where to place the other probe)

      Comment


        #4
        Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

        isl 6259 is a qfn chip ( small) on the board. put multimeter in dcv 20 volt. negative to a metal place like usb port or so, and the positive to pin 3 (starting from the little dot on the isl6259 chip. be Carefull to not touch other pins while measure the pin N°3 or u can burn something else. this chip on macbook are really small and is easy to make contact beween 2 or more pins together : example u touch pin 3 and 4 together and u will burn something.

        to locate chip and work a microscope or scope is better. i use a very cheap 20x magnifier, but do its work for now waithing to get a proper scope for that.

        edit: probable u7000 chip is up number 2 of your picture or nearby there.

        Comment


          #5
          Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

          Great info, nicely written too! I am at school right now, I will be home in a few hours, so I will let you know what I found, is the isl 6259 chip marked? Eg does it have this name printed on it? Apple likes to leave things without labels and to make their products repair- unfriendly.

          I only have a regular multimeter with normal probes, hopefully they are small enough. Just to double check, you want me to perform the tests with just the stripped board and charger plugged into it, nothing else plugged in right?

          Comment


            #6
            Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

            exactly only board and magsafe+ dcin adapter. put all on a safe place (not on the macbook alluminium conductive case).

            yes chip name is written on them.

            yes is a bad that apple (also samsung on ultrabook as far as i know) doesnt put component part near them....so to see one component what is u have to trace back from some big component near it

            repair macbook think is the hardest thing to do, 1° because it's not properly a normal notebook (has smc chip not bios), second all component are very small and not named. plus board absorbe heat very well.........

            ive burned some chip before getting into them properly
            Last edited by dellxps15; 03-27-2014, 12:04 PM.

            Comment


              #7
              Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

              Hi, so i plugged in a good charger and measured the voltage, there is 0 voltage on the white fuse. When I measure voltage on where the dcin adapter plugs into the board, there is voltage. Does this mean that the main fuse is blown?

              Also, when I put the probes on both sides of the fuse, the light on my multimeter comes on which I believe means that one of the probes is connected to a live wire, right? Thanks for your help

              Comment


                #8
                Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                if on fuse 4, you have voltage to one side and 0 to the other , fuse is bad, but before change it check with multimeter if there is a short. multimeter in diode mode; black to one metal place like external usb... the red to one side of the fuse at time. 000, 001, 002...008 means there is a short and replace the fuse will blow it again.

                if you have 0 volt both side of that fuse 4, we have to investigate more.

                hope that help.

                Comment


                  #9
                  Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                  Hi, yeah I know that, I checked the fuse both ways just to be sure, there is no voltage either way.

                  When i use the multimeter in continuity, diode mode, i put the black probe to the metal casing of usb connector and red to either side of the fuse, the value stays at 1 both times. So i guess that means there is no short?

                  Comment


                    #10
                    Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                    Btw just a theoretical question- how come that when i use the multimeter in diode mode and test the fuse (probe on each side), it tests positive on continuity? I would think that if it tests continuous that means the fuse is good (prob also a stupid question)

                    Edit: nevermind, i was just confused I guess, since there is no voltage either way, that means the problem is NOT the fuse. Got it. So do you have any other ideas?
                    Last edited by akotalik; 03-27-2014, 04:01 PM.

                    Comment


                      #11
                      Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                      near that fuse "4" there is a brown component C6905 0603 capacitors. check if it is short on both side

                      exactly no volt there should be that capacitors.

                      but no short on fuse... is strange... bad ac adapter connector ?

                      https://www.youtube.com/watch?v=fb3e...2CACC1&index=9
                      Last edited by dellxps15; 03-27-2014, 04:25 PM.

                      Comment


                        #12
                        Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                        Ok thanks, so I assume again the same test- black probe on metal housing, red probe on each side of the component? I cannot really find that capacitator, do you know where it is, does it have that full name on it? Seems awfully long on such tiny components. Idk if you can point it out in a pic....
                        Attached Files

                        Comment


                          #13
                          Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                          Well the magsafe dcin is good i believe, i bought a new one and when i plug in charger and measure voltage on the metal pins where it plugs into the motherboard (on the part where it is soldered to the board) it gives me 16 volts
                          Attached Files

                          Comment


                            #14
                            Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                            marked one is 0603 C6905, check if short on both side (without power)

                            with power, check voltage on that lines.

                            edit: from your last picture... are all inside pin of dc plug on mainboard ok and straight?
                            Attached Files
                            Last edited by dellxps15; 03-27-2014, 04:41 PM.

                            Comment


                              #15
                              Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                              Thanks a lot! When I put black probe to metal housing of usb and red probe to the capacitator, it says there is short on one side (the side closer to the white fuse). When i plug in power, there is 17 volts between the ends of the capacitator.

                              Comment


                                #16
                                Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                                c6905 shorted to only one side and volt to another is ok. now voltage goes from that 0603 to fuse 4 of your picture. remove fuse and see if track is damaged and also if voltage is present on fuse pin.

                                edit: if u can make a better and focused macro picture of white fuse 4 would be great

                                before remove fuse make a macro. you sure no voltage on fuse?
                                Last edited by dellxps15; 03-27-2014, 04:59 PM.

                                Comment


                                  #17
                                  Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                                  Attached are some macro photos of the fuse area. Let me make the measurement on the fuse again, but I am pretty sure there is 0 voltage between the ends of the fuse.
                                  Attached Files

                                  Comment


                                    #18
                                    Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                                    I am 100% sure no voltage between fuse ends. When i measure voltage between (either) fuse end and the capacitor end that is closer to the fuse, I get 16V. If I measure voltage between fuse end and the farther end of the capacitator, I get 0

                                    Comment


                                      #19
                                      Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                                      voltage on numbers:
                                      1:
                                      2:
                                      3:
                                      4:

                                      what is that burn on dc jack socket? check if inside pins are ok.
                                      Attached Files

                                      Comment


                                        #20
                                        Re: Macbook Pro Mid 2012 bad fuse?-Charity $$$ reward

                                        Burn- don't know, I was wondering myself. I did not touch this board with a solder. But it may be that someone else did of course.

                                        Voltage
                                        between 1 and 2: 17 volts
                                        between 1 and 3: 0
                                        1 and 4: 0
                                        2 and 3:17 volts
                                        2 and 4: 17 volts
                                        3 and 4: 0 volts

                                        DC socket pins are good- I would assume that since there is 17 volts on the capacitator, that shows that the dc in board is good right? I mean it supplies the right voltage into the board. Idk if there is another way to check that they are all good, since if you flip the board, the connections are not visible.
                                        Last edited by akotalik; 03-27-2014, 05:37 PM.

                                        Comment

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