Announcement

Collapse

Announcement

Welcome to the NEW iPad Rehab Forum! Everyone is welcome to read posts and learn for free. If you'd like to post your own question on the forum, please click "register" above or go here: https://forum.ipadrehab.com/register to enroll as a paid subscriber for $29/mo for unlimited access to our forum support and private signature failure section.
See more
See less

Ipod touch 4th gen charging problem

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Ipod touch 4th gen charging problem

    Heres a blast from the past, im not really doing this for profit as I cant charge anything decent for it so just doing it for curiosity. So what it did was not detect the charger at all. So I replaced Q4 and it now detects the charger, charges the battery enough to turn on, then current drops to 0.05a and then it'll turn back off again after a few seconds showing the battery is empty. Tried another battery also, have also tried jumping Q4 from B1 > B2 > B3 balls which works, but then when it turns on it has the same problem.

    So im putting this one down to some kind of current sensing problem. Iv checked R173 which is on the line usb_pwr_sense and its fine. There is another line called vbus sense, not sure if thats current related. By the look of it though vbus sense goes to Q2 which appears to be a mosfet that then opens Q4, but as we have jumped Q4 that shouldnt matter if that works or not.

    The thing about these is there doesnt appear to be any current sensing lines on the battery, there is just positive, negative and ntc and thats it. Im going to check the ntc line thermister in a moment, if its not that im pretty clueless now as the charge circuit is as basic as it comes.

  • #2
    Well I'm not taking the board out to test that ferrite so Iv diode mode measured the ntc line with battery disconnected. One board is 0.515 the other is 0.530 so looks good to me as don't think that much difference would cause a problem.

    Comment


    • #3
      Something funky going on with this one, measure a resistor on board A, solder it into board B and it reads a totally different value. I'd understand if it was in parallel, but it's in series and I'm measuring from one end of the resistor to the other....

      Comment

      Working...
      X