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Macbook A1466 dies when charger disconnected

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    #1

    Macbook A1466 dies when charger disconnected

    Hello all,

    Working on my wife's 13' Macbook air. It's been in a box since she upgraded but I figured it could be good practice.

    Details:
    Macbook 13' A1466
    Board (820-3209-A)
    Battery OEM 7.3v 50Wh 6700 mAh (020-7379-A)

    Pictures below of Boardview and schematic...

    I don't know how to test the voltage on a MacBook battery. I just assumed it had an enable pin but the best I could read was 300 something mV poking around the battery connector.

    It's an older model and it is very likely that battery has become toast after ten years of charging cycles. From my zillions of hours watching MacBook repair videos, however, I have learned there is a diode that can fail and kill the battery/prevent it from charging. Of course, I have checked it in circuit.

    D6905
    Red Probe on Pin 1 to 3 (.227) voltage drop
    Red Probe on Pin 2 to 3 (.227) voltage drop
    Seems normal

    Reversing probes
    Black probe on Pin 1 to 3 (2.330) voltage drop (Hmmmmm...)
    Black probe on Pin 2 to 3 (OL)
    Seems not normal

    Additionally:
    Red probe on Pin 2 to 1 (2.330) voltage drop (DCIN killing battery?)
    Black probe on Pin 2 to 1 (2.978) voltage drop


    SO I believe this diode to be bad but wanted to ask some other techs before ordering a replacement diode.

    Also, the diode says [Z5 23]. I can find nothing anywhere about the part number or specs of this diode. There was a random forum that said 20v 1 amp Schottky diode but that seems off. Also can't find that anywhere on mouser or digikey.

    If you could kindly:
    1) Advise if I am correct in the diode being "the bad guy."
    2) Provide me the part number for D6905 or equivalent.

    OR

    3)Tell me if I'm a silly goose and should just order the replacement battery and stop making things worse for myself and others.

    Thank you



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    #2
    Re: Macbook A1466 dies when charger disconnected

    Hi.

    1) connect the battery only. Meter in dc volts mode (20v or higher scale).

    2) black meter probe to ground. Red meter probe to the first pin on the battery connector. The first 3 pins are usually the V+ of the battery. Probe each pin and post the full list.

    3) batteries will often support 500 charge cycles and then derate on capacity. Good idea to purchase another from Amazon for testing. It can be returned if not needed. Check if the charge light goes on when battery is connected.

    Check ppbus_g3h at the fuse of the isl charger ic output with only the battery and then with both battery and adapter.

    Do also carefully check the voltage on each pin to ground of the dual diode at D6950.

    Post all measurements. We can find a replacement if required from Digikey / Mouser / Arrow.

    Comment

      #3
      Re: Macbook A1466 dies when charger disconnected

      Hello, mon2!

      Thank you for the quick response.

      Here are the Readings...

      BAT PINS: W/O ADAPTER IN
      1- GND
      2- GND
      3- GND
      4-0.1mV
      5-20mV
      6-20mV
      7- 0.465V
      8- 0.465V ALL dropped quickly to 155mV
      9- 0.465V

      AC Adapter plugged in:
      No BAT Connected- Green to Orange
      BAT Connected- Green to Orange

      ISL G3H FUSE F7040:
      BAT CONNECTED: 100mV and dropped to 1mv after a minute or so
      BAT CONNECTED W/CHARGER: 7.15V

      D6905 DC ADAP Plugged in:
      Pins
      1- 7.6V and climbing to about 8V in 20 seconds (Same readings on PIN 7-9 of BAT CONNECTOR)
      2- 14.75V

      After all that "charging" BAT voltage climbed to almost 2V and practically discharged a full volt in 1 min

      It seems like the battery is toast. But my question is, why does it seem like that diode is allowing reverse polarity when I tested it in diode mode?

      Comment

        #4
        Re: Macbook A1466 dies when charger disconnected

        I had something like this on an A1398 where the computer showed the battery at 71% but not charging. it also would not run on the battery. in my case the battery was faulty. I agree with mon2... it's best to have another battery to compare with.

        Comment

          #5
          Re: Macbook A1466 dies when charger disconnected

          Yeah, I agree.

          I just can't afford parts right now, unfortunately. Still don't know why the diode read as it did. I can only assume it is because it was in circuit. But when charging it seemed fine.

          Hopefully, when I get the new battery, we will be all set and charging will be normal.

          Thanks for all the help!

          Comment

            #6
            Re: Macbook A1466 dies when charger disconnected

            To properly rule out the diode. Very carefully flux and remove the part. You must be careful with the hot air as the hot air can kill the lcd panel. Once off the board, test the diode in diode mode again. The part is dirt cheap but shipping is always the killer in North America. You will need tweezers and the proper hot air tool to remove off the board. Or lean on one of the many local cell phone techs that should be in your region.

            Comment

              #7
              Re: Macbook A1466 dies when charger disconnected

              Good idea. I will do that before I install a new battery just to be sure.
              Thank you for the heads-up regarding the LCD panel.

              And yeah shipping costs are silly lol

              Comment

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