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A1989 (820-00850-A) Not powering ON, 20V on charger

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    #1

    A1989 (820-00850-A) Not powering ON, 20V on charger

    Hi everyone,
    its my first post here!
    Just a few things about me so you know who you are dealing with
    I am a complete beginner, never did any board level repairs. I have basic understanding of electronics and I do have a good DMM.

    I have a dead macbook pro, it had some light water spill at a USB C port and since then its not turning on. I may have make things worse by injecting 1.5V but Ill come to that later.

    I do have a boardview and schematic so I will use the names found there to explain the situation.

    When I first opened the laptop, the QB631 was completely corroded. I cleaned it with some IPA and started measuring around that area. Immediately found some shorted caps on PP1V8_SSD0. Assuming I can identify the shorted part by injecting some voltage, I added 1.5V to PIN1 of the C8832 (PP1V8_SSD0).
    That was probably a big mistake, because as soon as I did that, the short was gone. So either I killed something or I have no idea why my short on all the caps there is gone now.

    Current state:
    Plugin the MB into charger, it goes to 5V few sec. later to 20V at 80mA.
    T2 Voltages are all present, I cant find any obvious short. It seems to me, but again, I am a complete beginner, that U9000 has some issues.
    I will attach the schematic of U9000 so maybe somebody can explain to me if that IC should be on or not.
    The 3 coils that this IC is supposed to drive have 0V and that seem to be the power for the SSDs if I understand this right.

    Here is what I measured on the U9000:
    VDD_MAIN: 3.3V
    PGOOD: 3.3V
    All 3 Coils L9020, L9021, L9030: 0V
    ADDR: 3.3V
    V_BUF_1.8V: 0.0012V
    SSD_PMU_RESET_L: 1.8V

    My DMM thinks there are some shorted caps around the CPU area, but they show between 17-40 ohms and I remember reading somewhere that this can be normal for CPU area, doesnt nesserly means they are shorted.

    If you want me to measure something else, just let me know.

    Update:
    Reference to the location I got schematic and boardview: https://www.badcaps.net/forum/showthread.php?t=76497
    Attached Files
    Last edited by Kloper; 02-27-2022, 10:46 AM.
    Tags: None
    #2
    Re: A1989 (820-00850-A) Not powering ON, 20V on charger

    Check if all SSD voltages are present.

    Reference:
    https://boards.rossmanngroup.com/thr...ning-on.61479/

    Comment

      #3
      Re: A1989 (820-00850-A) Not powering ON, 20V on charger

      Hi, thanks for the feedback!

      PP2V7_NAND_SSD0 is not present, but I was assuming that U9000 is making the voltages for the SSDs, or I understand that wrong?

      Update:
      I shoot too fast, just realised there are more voltages for the SSDs, how ever non is present.
      PP0V9_SSD0: 0V
      PP1V8_SSD0: 0V
      Last edited by Kloper; 02-27-2022, 01:08 PM.

      Comment

        #4
        Re: A1989 (820-00850-A) Not powering ON, 20V on charger

        Voltage of PPBUS_G3H (F7000, pin # 2) ?

        Is PPBUS_G3H steady on the voltage ?

        Is the 20V on the charger static after reaching this rail or power cycling ?

        The 20V level is a good starting sign.

        Comment

          #5
          Re: A1989 (820-00850-A) Not powering ON, 20V on charger

          PPBUS_G3H is present with 12.5V and stabel.
          My USBPowerMeter looks stable.
          I found 1 pin that shows 20V on the board and it is stabel, how ever, I found a testPin that is jumping around, fluctuating alot cant even get a stabel reading.. its between 1-2 or maybe 0-2V on the TestPin TP(1)SAVE_XB_CC1_Z

          Comment

            #6
            Re: A1989 (820-00850-A) Not powering ON, 20V on charger

            Any idea what else I can check or what could be the problem?

            Actually, if U9000 should generate this voltages as soon as the laptop gets power, then thats clearly the issue, or not?

            Comment

              #7
              Re: A1989 (820-00850-A) Not powering ON, 20V on charger

              Confirm the voltage of SSD0_VR_P2V7_EN (R9082, pin # 1 or #2).
              PP2V7_NAND_SSD0 is not present, but I was assuming that U9000 is making the voltages for the SSDs, or I understand that wrong?
              U9000 is creating an enable signal pin that is to travel to U9080, ball # E4 (through the 0 ohm resistor @ R9082).

              Yes, U9000 appears to be the PMIC for the SSD. Perhaps it is corroded underneath the device.

              Remove all power.

              Consider to apply flux onto the top side / perimeter of this device. Apply polymide tape (kapton) on surrounding parts that you do not wish to disturb. You can also use aluminum foil to protect such tiny parts. It is not fun to fix nor find tiny parts that have flown away.

              Then with high heat but low air pressure, allow for the flux to melt and do its job. Proceed to move the hot air tool over the top surface of this device in circles. If required, increase the hot air pressure, slowly.

              Eventually the balls will melt and then gently nudge the chip at the corners.

              The chip should move away with the gentle nudge and then will bounce back into position of the wlcsp (BGA) pcb pads. This is what Louis calls - 'make it dance'. The process works very well. Do this 2-3 times and the balls should self correct underneath the device and create a fresh bond.

              While you are reflowing parts, consider to also reflow U9080 with the same technique.

              Be patient when you do this process, never push hard with the tweezers to nudge the chip as this can tear off the PCB pads and then it is game over. The hot air tool with enough heat + flux + air pressure will melt the underneath balls. We do not want to smear the solder balls nor flatten them - just correct the solder joints with the 'dance' of the chip. You can find assorted youtube videos on this topic from Louis Rossmann and Alex (NorthRidge Repair).

              Allow the part & board to cool for 5-10 mins at least.

              Then test again. Post your results.

              This part may need to be replaced but the SSD needs to be powered and that power is from U9000 as you have posted from the start of this thread.

              Comment

                #8
                Re: A1989 (820-00850-A) Not powering ON, 20V on charger

                R9082 has 0V
                I will try to reflow U9000 today... never did that before, so its gonna be interesting

                U9080 I think ill skip since the water never got there. Only a few parts on the edge of board ware effected, atleast visible.
                Ill update you after I did the reflow.

                Thanks for your help and time!!

                Comment

                  #9
                  Re: A1989 (820-00850-A) Not powering ON, 20V on charger

                  Reflow didnt work really... I was just too afread to melt the connectors next to it. I did heat the IC for while and components around it started turning shiny but the IC just didnt want to move so I stoped before I melt everything. I dont have microscope to really see well what I am doing there. I will see if I can get somebody who has more experience with this and let him try it, or replace the IC... I feel like Ill just make things worse.
                  Thanks for you help tho!!! Really appreciate it!!!

                  Comment

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