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    #41
    Re: MacBook Pro A1990 doest turn on

    The mosfet readings look ok.

    Try to dial up a higher voltage of 0v9 and check for a heated capacitor. Review the CPU Vcore input tantalum (polarized black) caps which create the 3 phase switching regulator circuit - collectively to support 128A of switching current.

    Comment


      #42
      Re: MacBook Pro A1990 doest turn on

      I shortened the wires, connected the common wire to two points to distribute the current, and raised the voltage to 0.9 volts. As a result, the current increased to 10 amps, but there is still no heat,
      At the same time the voltage at the input to the board, only 14 millivolts, with a current of 10 amps!
      I think the capacitor is not capable of making such a strong short circuit.
      Anyway, I don't have any good ideas yet.

      Very much short-circuited 0,014v:10a=0,0014ohm
      Attached Files
      Last edited by Ksansan; 01-19-2022, 03:43 PM. Reason: Upd

      Comment


        #43
        Re: MacBook Pro A1990 doest turn on

        Honestly, I am stumped.
        All the coil terminals are called to ground with a resistance of 1.4 to 500 ohms,
        And the resistance on the input terminals of the board is 0.0014 ohms, which is a couple of orders of magnitude less.
        It is obvious that none of the coils can be the source of this short circuit.
        Does anyone else have any ideas?

        Comment


          #44
          Re: MacBook Pro A1990 doest turn on

          Hey Mon2,

          I removed the board with the great video that you sent.
          Anything else that I might need to check just to be sure that I need to replace U7650 TPS51980A and afterwards CD3215C ( U3200 )?

          Thanks
          Nitzan
          Last edited by SMDFlea; 01-21-2022, 03:53 PM. Reason: removed full quote

          Comment


            #45
            Re: MacBook Pro A1990 doest turn on

            Hi!
            I have news: the capacitor C9081 was shorted.
            But to find it, I had to raise the voltage to 4.5 volts.
            I hope I didn't burn anything, because the operating voltage is 12 volts.
            It will take a couple of days to find a small ceramic for 10 microfarads.
            Then I'll try to turn the laptop on.
            Attached Files
            Last edited by Ksansan; 01-21-2022, 02:58 PM.

            Comment


              #46
              Re: MacBook Pro A1990 doest turn on

              Well done. I always get nervous about dialing up a higher voltage, just in case there is a short to something else.

              C9081, being only 10uF, will not be missed.

              See attached. You have ample bulk caps on that rail to proceed to test without this part if you wish. Just be sure that the low resistance to ground is now resolved which it appears to be from your last post.
              Attached Files

              Comment


                #47
                Re: MacBook Pro A1990 doest turn on

                Thanks for the tip, really enough capacitors there!
                No short, that's for sure, I can see a normal semiconductor wiretap.
                I will be able to try it only tomorrow.

                Comment


                  #48
                  Re: MacBook Pro A1990 doest turn on

                  Happy ending!
                  Mon2 Thank you so much,
                  Your help is invaluable, I definitely couldn't have done it without it!
                  The most amazing thing about this story is that it took a 90 amp current pulse to burn this capacitor!
                  It's unbelievable, but it's true.
                  And what is even stranger is that the R5620 resistor is still alive!
                  There is no error in the current, I measured it with a pliers.

                  I can't remember, where was this rubber band?
                  Attached Files

                  Comment


                    #49
                    Re: MacBook Pro A1990 doest turn on

                    Love positive endings !! Well done. You have some impressive tools. Fluke, while expensive are worth their value.

                    Ironically, pretty sure that I am dealing with a similar case. Need to deal with it next week.

                    Comment


                      #50
                      Re: MacBook Pro A1990 doest turn on

                      I will be following your struggle with interest!

                      Comment


                        #51
                        Re: MacBook Pro A1990 doest turn on

                        Originally posted by mon2 View Post
                        What are the diode and resistance readings for the CC1 & CC2 lines of these 2 type c ports ?

                        The resistance of the power rail is good but the voltage is still low.
                        Hey Mon2,

                        As I said I removed the board and re-read CC1 and CC2 lines of the USB controllers.

                        U3200 XB :
                        resistance:
                        CC1_CON : 5.6K
                        CC2_CON : 5.6K
                        Diode mode:
                        CC1_CON : 0.85v
                        CC2_CON :0.85v

                        U3100 XA :
                        resistance:
                        CC1_CON : 5.6K
                        CC2_CON : 5.7K
                        Diode mode:
                        CC1_CON : 0.85v
                        CC2_CON :0.85v

                        UB300 TA :
                        resistance:
                        CC1_CON : 5.6K
                        CC2_CON : 5.6K
                        Diode mode:
                        CC1_CON : 0.85v
                        CC2_CON :0.845v

                        UB400 TB :
                        resistance:
                        CC1_CON : 5.6K
                        CC2_CON : 5.6K
                        Diode mode:
                        CC1_CON : 0.825v
                        CC2_CON :0.84v

                        What do you think?

                        Comment


                          #52
                          Re: MacBook Pro A1990 doest turn on

                          Originally posted by Ksansan View Post
                          Happy ending!
                          Mon2 Thank you so much,
                          Your help is invaluable, I definitely couldn't have done it without it!
                          The most amazing thing about this story is that it took a 90 amp current pulse to burn this capacitor!
                          It's unbelievable, but it's true.
                          And what is even stranger is that the R5620 resistor is still alive!
                          There is no error in the current, I measured it with a pliers.

                          I can't remember, where was this rubber band?
                          I hope to have the same ending

                          Comment


                            #53
                            Re: MacBook Pro A1990 doest turn on

                            Hi @noz_1974. The readings look ok to me. Perhaps UB400 may be an issue. The diode readings look a bit off compared to the others. Can you check these values again to confirm ?

                            Also, came across an interesting widget on Aliexpress - 'U301' which may be linked to your issue. We are very close to considering to buy this new tool.

                            Anyone in the forum have any comments or feedback on this gadget ?

                            Found it here - check out the video:

                            https://www.unionrepair.com/by-u301-...up-repair.html

                            Adding more videos on this tool:

                            https://shop.rewa.tech/detail/baiyi-...ok-repair.html

                            Have you gone through this checklist for your case ?

                            https://repair.wiki/w/Charger_stuck_...nstead_of_20_V
                            Last edited by mon2; 01-22-2022, 09:59 AM.

                            Comment


                              #54
                              Re: MacBook Pro A1990 doest turn on

                              Originally posted by mon2 View Post
                              Hi @noz_1974. The readings look ok to me. Perhaps UB400 may be an issue. The diode readings look a bit off compared to the others. Can you check these values again to confirm ?

                              Also, came across an interesting widget on Aliexpress - 'U301' which may be linked to your issue. We are very close to considering to buy this new tool.

                              Anyone in the forum have any comments or feedback on this gadget ?

                              Found it here - check out the video:

                              https://www.unionrepair.com/by-u301-...up-repair.html


                              Have you gone through this checklist for your case ?

                              https://repair.wiki/w/Charger_stuck_...nstead_of_20_V

                              Hey @MON2,

                              Double check UB300 and everything is fine.
                              About the check list : before the short that I made by accident I had PP3V3_G3H,
                              and I had all the LDOs voltages of U3200 without the 1.1v.
                              So from here its CD3215C / ROM or T2 chip problem, at least as I see it.

                              About the tool that you published , I saw few videos who using this tool. For me, its to much , because I only bought the computer as a small project

                              Comment


                                #55
                                Re: MacBook Pro A1990 doest turn on

                                and I had all the LDOs voltages of U3200 without the 1.1v.
                                Ah yes. I recall now. I think it is practical to replace U3200 for this single reason. When you source the part, insist on a 100% new and original - not a reballed part. Then flux the area well and continue in circles till the chip dances with a gentle nudge of the tweezers. Take your time - high heat and fair amount of hot air pressure. Do not rush this step else you can rip the PCB pads off the logic board. You will know when it is time when the chip moves like on melted butter. Then flip it off the PCB.

                                Use kapton (polymide) tape to protect surrounding parts.

                                Apply normal leaded solder over the pcb pads to permit lower temp reflow of the fresh part.

                                Again, use solder braid with high soldering iron heat to remove the excess solder.

                                Finally, use alcohol to clean up the pads that have been tinned with the low temp solder.

                                Flux again. Seat the fresh part and low air pressure and allow for the balls to melt into place. Increase the heat once the balls have started to melt and nudge (dance) the IC into place.

                                Comment


                                  #56
                                  Re: MacBook Pro A1990 doest turn on

                                  Hey Mon2.

                                  Quick question.
                                  can I remove the black cover ( marked in blue) from the board when I am trying to replace U3200 ( marked in red)?
                                  I want to be able to see if any components ( below the black cover) were moved from their place during the U3200 replacement.
                                  If I can remove it, how shall I do it, and how to reattach it in the end?
                                  Thanks
                                  Attached Files

                                  Comment


                                    #57
                                    Re: MacBook Pro A1990 doest turn on

                                    Originally posted by noz_1974 View Post
                                    Hey Mon2.

                                    Quick question.
                                    can I remove the black cover ( marked in blue) from the board when I am trying to replace U3200 ( marked in red)?
                                    I want to be able to see if any components ( below the black cover) were moved from their place during the U3200 replacement.
                                    If I can remove it, how shall I do it, and how to reattach it in the end?
                                    Thanks
                                    There is an ordinary piece of cardboard glued there that can be removed and put back on if necessary.
                                    When you solder the chip, put a piece of thin iron over the cardboard to protect it from the hot air.
                                    If you have never soldered such a chip before, practice on something unnecessary.
                                    Sorry if I got in the wrong question.
                                    Last edited by Ksansan; 01-26-2022, 05:12 AM.

                                    Comment


                                      #58
                                      Re: MacBook Pro A1990 doest turn on

                                      Originally posted by Ksansan View Post
                                      There is an ordinary piece of cardboard glued there that can be removed and put back on if necessary.
                                      When you solder the chip, put a piece of thin iron over the cardboard to protect it from the hot air.
                                      If you have never soldered such a chip before, practice on something unnecessary.
                                      Sorry if I got in the wrong question.
                                      Hey @Ksansan ,

                                      Can you send me a link to this cardboard?
                                      I guess that you don't mean to Kapton tape

                                      Thanks

                                      Comment


                                        #59
                                        Re: MacBook Pro A1990 doest turn on

                                        Originally posted by noz_1974 View Post
                                        Hey @Ksansan ,

                                        Can you send me a link to this cardboard?
                                        I guess that you don't mean to Kapton tape

                                        Thanks
                                        You can of course use capton, and that's a good solution, but you can take a piece of metal from a can and cover it with
                                        If you mean the black cover on the laptop board itself, it's just a black material that looks like heavy paper, like a postcard.
                                        Attached Files
                                        Last edited by Ksansan; 01-26-2022, 10:09 AM.

                                        Comment


                                          #60
                                          Re: MacBook Pro A1990 doest turn on

                                          Originally posted by Ksansan View Post
                                          You can of course use capton, and that's a good solution, but you can take a piece of metal from a can and cover it with
                                          If you mean the black cover on the laptop board itself, it's just a black material that looks like heavy paper, like a postcard.
                                          Okay, nice solution. I thought maybe you are talking about unconducive material.

                                          Comment

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