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iPhone 6 Plus DFU Boot

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  • iPhone 6 Plus DFU Boot

    Hi There,

    I've another iphone 6 Plus with touch issue. I've replaced meson and cumulus then tried to test the phone but it was not booting anymore.
    I've plugged it to a power supply and no electricity leak but when i boot the screen stay black with 0.07 to 0.12 amps draw and stay flat on this value.

    If I plug it to my computer, iTunes detect it in recovery mode and ask to update. But when It finish to download the software and try to install I get the error 40.
    I know error 40 is something with NAND related but in nowhere I heated this zone, only near the touch IC's

    I've took the volt measurement on PP3V0_NAND and PP1V8 and PP3V0_NAND is almost 0. PP1V8 is ok.
    Should I remove the power ic ? Because PP3V0_NAND is generated from the power IC.

    Someone already had this issue ?

    Thank you

  • #2
    If you've replaced cumulus and meson and the phone isn't booting the logical first step would be to remove them again to see if it works again. I'm not sure about cumulus, but a badly replaced meson can and does give you a dead phone. If you remove it the phone will probably come back alive. It's quite easy to bridge a ball on meson as much smaller balls than cumulus.

    Comment


    • #3
      that's when i replaced cumulus that the phone stopped from working. Do you think It's possible to apply too much heat and maybe create a bridge or something ? And this create a voltage drop on PP3V0_NAND ?

      Comment


      • #4
        Yes it's possible to overheat the cpu, wifi etc and spew a balll out if you add loads of heat.
        id try taking the two touch ics off first and leave them off until you figure out the problem

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        • #5
          The thing I noticed is some micro balls on the other side of the board next to the CPU but not big solder balls like from a IC just micro balls. The CPU is still intact on the side.
          I checked evrey single components and IC's and understand where it's coming from. It's possible these balls come from when I removed the shields ?

          Comment


          • #6
            Argh that's not a good sign, it's possible they came from the shield but also possible from the cpu / ram. What you want to try and do is turn the board on its side and do an inspection through the holes before you remove the shield to see if you can spot any balls. It's possible it's come from an inductor as they just love spewing solder. By the readings from your power supply it sounds rather dead.

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            • #7
              But how this is possible, i just heated like at 350c the cumulus during 20 sec and protected everything with tape. these micro balls look like the ones in solder paste. in fact It seems that there were solder past above the CPU. But this was never opened, i'am 100 %sure

              Comment


              • #8
                Are you sure it's solder paste and not the cpu transfer compound they put on top of the cpu ?. By the way tape doesht do anything, try putting tape on the end of your finger and then blast it with hot air, the only thing it does is stop things blowing away. I use coins or offcuts of copper sheet.

                did you remove cumulus and meson to see if this resolved your problem ?, as if the phone stopped working after you changed the touch ics its highly likely they are the reason it's not working. I have had the same situation as you more than once and it was pretty much always the chip I had just fitted that was the problem because the chip was either bad or I had managed to bridge balls under it.

                Comment


                • #9
                  I'am going to try to remove it as soon as I can and let you know. Thanks man your help is appreciated

                  Comment


                  • #10
                    Here are my thoughts on this post.
                    1--Why did you change cumulus? The current best practice for touch defect in 6 plus is lifting meson, placing M1 jumper and replacing meson (same chip or new). In the two years of research on touch disease, we've learned that cumulus is rarely at fault. Changing cumulus adds SIGNIFICANT risk to the overall repair and subjects the board to more heat, and more chances of secondary problems.

                    2--" protected everything with tape" Don't do that. Tape creates the problem you are trying to avoid. Tape restricts the airflow dynamics so that you have to apply too much heat to the board to get the same effect as if you had no tape. Use a coin instead, and not too close to where you are working.

                    3--Whenever you have a board with a new problem that it didn't have before you did X, you go back and erase the last thing you did. Meson and cumulus are now variables, so taking them off is a good idea, even if they are not related to your problem of 3v0NAND, the fact that you got a 3v0NAND problem from this procedure means that the likelihood that these chips are not placed well is high.

                    4--You have a brain dead phone. You are measuring 0v at 3v0NAND. Why? What happened to your NAND voltage? THIS Is the heart of board repair---weighing different possibilities and figuring out what is MOST LIKELY.
                    Let's make it multiple choice:
                    A---It was never produced because the PMIC that makes it is not itself getting power or told to turn on.
                    B--It is not making it to NAND area because of an open line.
                    C---It is being produced, but there is a short to ground on the line and the voltage is going to ground and = 0v

                    ^^Which one of these is most likely? Once you figure that out, you'll want to use a multimeter to confirm your theory and then make a plan to address it.

                    Comment


                    • #11
                      @Jessa_the_Professa Why I removed cumulus ? Because I've removed meson, done a jumper + UV solder back meson and still no touch at all.
                      Last edited by yauuik; 02-14-2018, 11:05 PM.

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                      • #12
                        I removed both cumulus and meson and still no booting

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                        • #13
                          Read my question to you and answer it—i
                          made it easy, multiple choice!

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                          • #14
                            Can I answer??

                            why is it 0V

                            IS the PMIC working?? yes or no
                            Last edited by eDigitCom; 02-15-2018, 04:09 AM.

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                            • #15
                              I think it’s power ic since not a single cap is shorted. I’ve low value on gpu and cpu lines and my fluke is beeping but that’s normal for thoses lines

                              Comment


                              • yauuik
                                yauuik commented
                                Editing a comment
                                For the caps question is B of course. Yes i know if one is bad all the others on the line will be shortened too
                                What I mean is for all lines coming from PMIC I dont' find any bad caps on these lines :-)

                              • yauuik
                                yauuik commented
                                Editing a comment
                                For the first question I'll say C since I have almost 0v on the line and the CPU become extremely hot

                              • yauuik
                                yauuik commented
                                Editing a comment
                                What kind of faults can heat cause? Melt solder below IC ?
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