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ip7 no prompt to boot after fall damage (done by us yay!)

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  • #16
    Checked all i2c lines that pass trough tristar or Tigris and their pull up to 1.8v sram resistors and everything seems fine. Beside dead pmic what else should I look to?


    • #17
      Assuming the phone was tested after audio IC Job

      Here is a few things I would do.

      Does iTune detects the board?
      maybe stuck in dfu

      what is the diode mode measurement at the battery connector?
      One side should read about .4V, reverse the polarity and you should get a reading that starts at around 1V which then gradually moves up to open line. This will confirm that you have no problems at the battery connector, and more then likely no issue on battery rail and vdd main

      Connect with power supply and try to prompt to boot via usb, and via power button connection while the board is out of a frame. Take notes of the current readings.

      Try to same test, but apply pressure on different areas of the board, and look for any changes in the current consumption. If a chip is partially connected, you might be able to pin point the general location of that chip.

      4. Inspect visually the board very closely for damaged component or connectors. Maybe your assistant screw driver slipped at some point. Triple check around audio IC for anything that might of have been slightly bothered while doing the job, and shifted when it feel on the ground.


      • #18
        1) no. it is not detected
        2) i do not remember right now but i diode mode comapred this whole phone trough ALL fpc to a good board. nothing was off. vdd main was present. as every other voltage beside baseband and gpu
        3) as i said i tried prompting from usb, from button, externally with a brand new buttons flat, a brand new dock flat, everything you might think i tried it.
        4) i checked every single piece of that effin board and nothing was off. the audio ic is perfect. as i said i also replaced it later again with leaded, the audio ic is not the problem, thefall damage is the issue. Federico in the uk had one with the exact synthomps and he solved it reballing the cpu after a fall damage

        as i said, it worked fine after the audio ic replacement. it died after the board fel on the ground
        Last edited by DocVolt; 12-07-2018, 10:20 AM.


        • #19
          Can you show us a standard video of current consumption on dcps at prompt to boot by power button? I like to eliminate variables and using the multimeter to report current is a variable by itself. If the phone really is less than 100mA at prompt to boot by both power button and usb then I’d consider cpu reset or crystal or a power supply to cpu. But there has to be a mechanism for failure. Pmics don’t go bad from a drop, tristar doesn’t go bad from a drop.

          But iphone 7/7p is very susceptible to drop and it typically manifests somewhere around the cpu. I have seen a cpu power coil pop off, and of course 1v8sdram short within ram.

          Look very very very closely for tiny cracks in the underfill around cpu to see if you can find a spot that was damaged. Then I’d apply pressure there and see if anything changes


          • #20
            i posted a video earlier, ignore the minus sign,

            the amp meter is beetwenn the bench psu and squid black banana plug, i do not have the phone with me atm to take another video but i will do as soon as i can.


            • #21
              Before you give up on this phone remove the Nand and see if iTunes detects it. I have had two in the last week an 8 and 7 both were dropped. All the voltages check out like yours. I am waiting for a test fixture for the JC before I put any more time into them.