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iPad 5th Gen A1822 Shorted Stuff around PMIC

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  • iPad 5th Gen A1822 Shorted Stuff around PMIC

    Hey, first time doing iPad repair in a long long time, and first time working on an iPad board, I've done MacBook board repair for 5 years though. On this A1822 it was drawing nearly an amp on charger in, traced it down to this diode circled in red, when I removed it there's still a short on either side of ~1ohm, I tired injecting 2 volts on the coil side with my bench PSU which seems like it wasn't ground, and it pulled ~500ma, which wasn't hot enough for me to trace down anything else shorting with freeze spray or alcohol. This is around the pmic. Anyone have experience with this, I have a bad feeling it's just the pmic I need to replace.

    Edit: no history of the device never been opened and no liquid damage.
    Corbina
    Friendly Contributor
    Last edited by Corbina; 07-30-2021, 08:58 PM.

  • #2
    Let's take this one from the top.
    What is the history of the device and what is wrong with it?

    'drawing nearly an amp on charger in" is not a problem--that's the normal behavior of a working iPad that is connected to a usb charger.

    To save some time, let's assume that the problem is that the device does not appear to turn on at all.
    Return all components that you've removed so we can troubleshoot this from the top.

    The first step with an iPad that does not turn on is to attach a DC power supply to the battery connector using alligator clamps and then prompt to boot with power button or usb and observe the current consumption. Show us a video of that step.

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    • #3
      Update and Fixed: So the zenner diode circled in red was dumping the short to ground, and after asking around and getting ZXW from store.ipadrehab.com I was able to determine I had a short on VCC Main. So I kept trying to inject 5V and look for the heat as it was drawing up to 15w, but the only thing getting really hot was the power supply cables. So after some stupidity I removed the PMIC seeing it was the only thing getting mildly warm, but unsurprisingly the short was still there. So after looking again with my not so great thermal cam, I was able to see the little cap getting ever so warm which was it. So solved!

      Thanks to Tim Herrman and John Barelli for the help.

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      • #4
        PMIC is almost never that cause of a vccmain short in iPads, and the charging diode is unrelated to your main short.

        We would have recommended solving this problem very differently, but it sounds like it is fixed now. Good job.

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