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iPad mini 2nd gen charging only while off

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  • iPad mini 2nd gen charging only while off

    This iPad mini only charges while is still OFF and during boot, when it turns on fully booted then it stops at around 2% charge

    I do have only 4V on L5700 coming from the charging port when the battery is connected, but if I unplug the bat and connect to charger it shows 5V.

    tristar 3V and 1.8V are present but my other 5V are only 4V if the battery is plugged in while charging not sure if this is a clue or not.

    I do not have a donor board for this so I cannot compare any diode readings.



  • #2
    Sounds like some current sensing problem to me, takes more current to be on + charge than to be off & charge.

    Comment


    • #3
      Originally posted by larossmann View Post
      Sounds like some current sensing problem to me, takes more current to be on + charge than to be off & charge.
      Thanks for your answer Louis! I did check the BATT_SNS / PPBATT_POS_CONN line and it was 0.499 which I cannot compare but it looks fine to me also on the SNS line I checked the two resistors and those were good.

      I did went ahead and replaced tristar just because why not. but no luck there

      Also tried pressing on the PMIC but nothing, as soon as the phone boots if you disconnect the usb and reconnect it never charges again also the pc does not detect.

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      • #4
        Check what voltage is coming in from the USB port at the first large ferrite on the USB power line. When iv seen this issue before that voltage has been low. Also test it without the battery plugged in. The iPad I had with a similar problem had about 3.9v instead of 5v on that line. So bad charge port / soldering / line from charge connection.

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        • #5
          Originally posted by crea2k View Post
          Check what voltage is coming in from the USB port at the first large ferrite on the USB power line. When iv seen this issue before that voltage has been low. Also test it without the battery plugged in. The iPad I had with a similar problem had about 3.9v instead of 5v on that line. So bad charge port / soldering / line from charge connection.
          Hey Crea2K thanks for your input once again I really appreciate it, On the first post I mentioned this exact same scenario I get only 4V coming from the port while charging and if I remove the battery from the equation then I get 5V so when you had this issue in your case was the charging port? I already ordered one since I thought I had in stock but nope

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          • #6
            When I removed the battery the voltage stayed the same, leading me to the charge port. If the voltage changes when unplugging the battery that would lead me to think it's something else. Iv seen that issue you have before but could never work out what causes it.

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            • #7
              I have a similar trolly mini retina. I spent a few minutes with it yesterday and found that is was same despite two ports and two tristars. It will pull normal charge current when first connected to usb, and will continue to charge normally at times, but will drop current to 0.10 after connect/disconnect of charge port, but not after connect/disconnect at usb charger. This points to something between lightning port and tristar output. I first thought it was current sensing as well and tested two known good batteries and pulled screen from Device while on—no change. I do feel like there is a hot spot on bottom of board so it may still be a current sensing problem.
              I may not put more time into it—only out of curiosity, it has crossed the line into hobby project now. If I do, my next step would be diode mode under tristar and maybe investigate the interrupt line with some experiments on a known good—always wanted to see if interrupt line fault would explain these ones that charge at first but not later—ie tristar can’t get the attention of cpu to inform usb permission

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              • #8
                That would be cool if you could do one of those as a hobby project when you can and do a stream on it as that's my number one iPad troll

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                • #9
                  Wow I will still update this case here when my charging ports arrive since we all have slightly different scenarios mine could still be the port even if it looks in pristine condition.
                  I will definitely watch that stream as always

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                  • #10
                    Any luck yet? I have exact same thing, nothing knocked off.

                    Cheers, TVtechcellphone

                    Comment


                    • Jessa_the_Professa
                      Jessa_the_Professa commented
                      Editing a comment
                      Yours is very different--the history was dented charge port, which is less likely (or impossible) to cause electrical damage to the charging system. Without that charge port physical damage, then electrical damage becomes the mechanism and that leads to chip damage. By now, all the cases of 'state-specific charging' end up being the ipad version of tigris--i.e. the PMIC.

                  • #11
                    Mine is ipad mini gen 2:
                    Ouch. That what I figured on about this PMIC by studying the ZXW. This replaces the "trigis". But which mosfet with diode transistor to bypass with wire for testing? Replace PMIC or try updating the iOS if it is corrupt?

                    Cheers, TVtechcellphone
                    Last edited by TVtechcellphone; 11-03-2018, 07:38 PM.

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                    • Jessa_the_Professa
                      Jessa_the_Professa commented
                      Editing a comment
                      I've never heard of iOS problems causing anything like state specific charging.
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