The iPhone 6 LCD screen has some problem, so we replace it and then we try to turn on iPhone to test, after we press the iPhone power button, the iPhone 6 won't boot, it just stuck on white Apple logo and then auto restart. We need to solved it.
According
to repair experience, we need to check iPhone CPU part. Check the bus and reset first, both
of them are normal. Cut the shiled cover above the fingerprint, use Fluke 15B+ digital multimeter to measure the
resistance of CPU to the clock and data.
The
normal values of R0317 and R0316 are more than 400, the measurement of R0317
resistance is 745, and the R0316 is 479. This case is mostly the two pin of
AP31 and AR31 in the right lower right corner of CPU has pseudo soldering.
First press the iPhone 6 CPU to test
whether the device can turn on or not, do not try to reflash the phone first,
it will report error 9. Of course, the best method for CPU pseudo soldering is
redo the parts, here we try a method of jumper wire connection without removing
CPU necessary (6 and 6P can be common used).
As
shown in picture 17-1-1, look at the position of
the two points on the wuxinji schematic diagram,
the lower right corner is 0, the width is 1.45MM (the width of 4 solder
joints), the height is 1.75MM (the height of the 7 solder joints), which can be
slightly shaved on this basis, first probably draw a rectangle. When the upper
cover is very hard, do not use brute force, select a sharp phone repair blade,
you should slow down when finish scraping on the white pad from cover to the
CPU upper cover, after scraping the white pad, the point we are looking for
will come out, the wire on the CPU chip must be operated under the HDMI Camera microscope.
First
test the resistance of the two points. If normal, smear green oil on the top
(except for the two points we are going to connect jumper wire). After the
curing we can connect jumper wire, use QUICK TR1300A hot
air gun to blow very small tin
balls on the 2 points respectively , we choose to use the wire of the receiver,
it's thinner, the receiver wire is with glue, scrape the 2 ends and apply a
little solder. As shown in picture 17-1-2.
Use
jumper wire on the corresponding two points separately. ( it's better to do on
both two points to avoid rework repair). Once you finish flying, just apply the
green oil and use 5V USB Ultra Violet Light Lamp for curing.
Now, meausre the iPhone 6 agian, the data is normal. Install the iPhone,and press the iPhone power button, now the iPhone 6 can be turned on smoothly.
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