Iphone 5 unknown device – iphone mobile

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Iphone 5 unknown device – iphone mobile

On January 23, 2015, Posted by , In iPhone, With Comments Off on Iphone 5 unknown device – iphone mobile

I have iphone 5. It was dead. Ive changed U2 and everything is working now exept usb. When i try to connect to computer it shows me unknown device. I tride another computer, original cable, i even change U2 and nothing working. kindly to be helped

No Comment so far:

  1. ExpertBuddy says:

    U2 responsible for usb and uart. In some cases , when it burn, voltage +5v can go to CPU usb data lines and cause breakdown of these lines. Also, u2 is very close to CPU and when you replace it there is a possibility of overheating and solderings balls under processor. CPU is very hard to reball, so do special analysis before reball. Try remove U2 and measure resistance between GND and contact pad that go to usb data lines. It should be equal and not in short circuit between d+ d- data lines. Also you can apply a 2v on laboratory power supply Along with stabilized amperage 100mA to contact pad of data lines. CPU should not consume a lot of current or be heated.

  2. Wela says:

    Thanks for reply… This problem was before ive changed u2 so i think this is CPU problem… im shore that i do not overheat cpu. There is no other posibilites? some capacitor, jumper etc? If this really cpu this phone is trash

  3. ExpertBuddy says:

    So thats another thing if it was the initial problem.
    1 Check or replace dock
    2 Check 5v on C304 capasitor Along with usb inserted
    if not ok- replace Q2 (usb 5v protector) and check or replace r111(5v fuse)
    3 Check l20 l22 fl60 fl53
    4 Check L1 L8(data lines inductors between U2 and CPU)
    If all ok, it can be CPU- how to check CPU in first post.

  4. ExpertBuddy says:

    I also did not work////////

  5. newComer says:

    Ive checked eveything, i replace u2 one more time but still problem exist…

  6. julianz says:

    Along with iphone 5, you have to be careful Along with tempreture, even when soldering on a coil, an underboard pre-heater is a good tool to have for these.

  7. Wela says:

    I replaced a lot of u2 and this is my first case Along with this kind of problem. Unfortunelly any solution in this topis was not worked. So i think this is cpu. Client wont be happy but what to do title=smile thanks for replies !