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820-3476-A Won't Charge Battery/Run Off Charger

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  • 820-3476-A Won't Charge Battery/Run Off Charger

    Hope someone can help with this one as it's proving to be a complete pain.
    History: Macbook brought in with liquid damage and no power. Inspection revealed liquid damage around Q7130 which had also burned Q7130 and the CHGR_PHASE pad underneath. Smaller amount of liquid damage around U7100.

    What I have done so far:
    Run a jumper wire for CHGR_PHASE between Q7130 and L7130
    Checked for any obvious shorts to ground on PP_BUS, CHGR_PHASE, CHGR_LGATE, CHGR_SGATE - found none
    Replaced U7100 and Q7130 - multiple times as a pair with new chips
    Replaced R7121 and R7122 and checked resistance between pins 27 and 28 of U7100 to confirm 20ohms
    Replaced R7151 and R7152 and checked resistance between pins 17 and 18 - found even after replacement it wasnt 3ohms so traced the fault back and found no continuity between R7152 and R7150
    Ran a jumper wire between R7152 and R7150 and checked resistance between pins 17 and 18 - now reads 3ohms
    Replaced R7125 and C7125 as they didnt look nice - tested ok with the meter but replaced anyway
    Found R7185 is only reading 1.2kohm instead of 470k as per spec - replaced it and C7185 but it still reads 1.2kohm makes me suspect Q7180 has an issue but I am getting PP_DCIN_CHGR at 19v with my 85w charger.

    Currently the board will:
    Run fine off a charged battery - which points me squarely at an issue with the charger input side of the circuit.
    It will also run off a charger but I believe Q7130 to be partially burned now as it is allowing around 17V through it to make PPBUS 17v which obviously means the system won't charge the battery as the voltage is to high.

    Just for reference with a previous Q7130 and U7100 I was only getting 4V on PPBUS

  • #2
    Replace the ISL, Q7130, and Q7155 all at the same time. Also double check all traces under and around Q7130


    • #3
      You can also check scl/sda lines diode mode, they should be really close one each other, usually around 0,489-0,500.
      Check resistor values R5380, R5381.
      Check for any short on both lines.
      Make sure U7100 is well soldered.


      • #4
        "R7185 is only reading 1.2kohm instead of 470k"
        Change Q7180, as bad; it has leakage at least.

        "Run a jumper wire for CHGR_PHASE between Q7130 and L7130"
        Have U7100 and C7125 good connection to the same point?
        Open trace for R/C7125 will burn Q7130 (its high-side).


        • #5
          Thanks for your replies - can confirm after having replaced Q7180, U7100 and Q7130 again and also running a jumper wire for CHGR_PHASE from L7130 to C7125 the macbook is now charging and producing 12.3v PPBUS from the charger as normal.

          thanks for your advice.


          • #6
            "producing 12.3v PPBUS from the charger as normal."
            That is not normal!
            Unless your multimeter doesn't read correct.

            Battery is charging?


            • #7
              12.3 is a little low is this off battery power? If not, does it charge recognize and run off the battery?


              • #8
                my meter does read a little low normally - yes the battery is charging as normal. Keep meaning to invest in a better meter!


                • #9
                  Gotcha then yeah for SURE get a new meter! It could cause issues on future repairs but good job fixing it!


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