In the field of iPhone repairing, if the
iPhone 6 Plus reboot repeatedly, this time you should consider fixing the
unknown error 9. Use iTunes to root it, it shows unknown error 9, most of this
is caused by the CPU and NAND flash. What
exactly is it? We need to test it to determine the real problem.
Test the R3017 and R3016, (they are
positioned in the bitmap as follows 3-2-1 and 3-2-2) Normally both of them should be 480. If
one or two of them shows 700, then the CPU must broke. After testing, we can
found that the AR31 of CPU was disconnected.
Remove the CPU, and them we found that the motherboard leaking
copper. Please don't worry, we can handle it. Use solder iron and solder flux
to solder it.
Clean the remaining glue on the solder pad.
Pre-heat the motherboard with hot air gun ,
and then remove the glue with solder iron .
In this part, you should do it more carefully, the best way is put solder pad
under the microscope, so that you can see it clearly, the picture as shown in
3-2-3.
After cleaning the solder pad, we start to
handle the problem of copper leakage (semi-finished as shown in 3-2-4)
Because both of two points are easily
disconnected, so we jump wire on AR31 and AP31, as shown in picture 3-2-5 and 3-2-6.
Next we need to remove glue and plant tin
on CPU. The method of remove glue is same to process the solder pad, please
refer to that method. The lower CPU board must be handled well, because it
directly affects the installation of upper CPU board. Carefully check the pins;
the level of the protruding pins should be the same. For the novice, it is
difficult to plant tin, here are some tips. The most important of plant tin is
the location of the CPU and the BGA reballing stencil, you need to target them exactly. Don't
shake your hand when you blow it and don't move the stencil, use hot air gun to
blow it from one side, in the meantime, keep tin beads in place, don't move and
its size should be the same, as shown in picture 3-2-7.
Now assemble the CPU and the upper CPU
board. When you finish it, use multimeter to measure the diode data of the Power Drive control IC. When press the power
button, the current will be set at 80 MA, then connect to the computer, it will
automatically enter DFU mode. We can use these two steps to initially determine
if the CPU is installed. On the other side, we need confirm whether the CPU is
good by rooting the iPhone which will report unknown error code 4014, and we
also need to check the jump wire, if both were around 480,then the wire was
mended, as shown is 3-2-8/9.
Assemble the upper CPU board and put it
under the microscope to check whether all is welded, then connect to the DC supply power to measure the current, the normal current
is 450-500MA. If not assemble it well, it will shows large current. After
testing, the current is normal. However, when we root it, it is stuck in the
Apple LOGO and the progress line doesn't appear, the CPU was hot, there should
be somewhere short circuit, so we use rosin method to find the trouble(as shown
in 3-2-10), and then fix it.
Finally, all the problem was solved, power
on iPhone 6 Plus, it can display the data line. After root it, the iPhone 6
Plus can be turn on successfully.
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