After use iTunes to update the IOS on iPhone 7, the iPhone cannot be turn on anymore, it just stuck on Apple logo. How to solve it?
Remove
all iPhone external accessories, and then test it again, the result is the
same.
Disassemble the iPhone 7 by phone opening tools, and then measure the iPhone motherboard by DC power supply, the power scurrent stop at around 150mA. Touch the iPhone home button, it has response, and the flash can be finished normally, which means that the iPhone booting condition is normal.
Press the iPhone power button, after a
while, it gets into interface, but the iPhone still runs slowly, and we found
that if we clicking on the file or interface related to the sound, the iPhone
will get stuck and stop running. As we know, the iPhone 7 audio IC is easy to
damage, so we decided to take out the U1301 big audio to check.
Before we take out the iPhone audio IC by
using QUICK 861DW hot air rework station, we need to protect
the other ICs next to it ( below it is iPhone Nand flash, above is a iPhone
large power IC, on the back is the iPhone baseband CPU)
After remove the iPhone big audio IC, we
found the problem on the solder pad. The solder joints of the two pins of the
chip C12 and J12 have been lost. Observe it under the 7-45X Trinocular Stereo Microscope, finding that the jump wire between C12
and J12 is easy to disconnect. Check iPhone schematic diagram on WUXINJI Dongle, there are 2 capacitors next to this
audio, there are two resistors next to the audio lead to these two points
respectively.
Welding jump wire to these two points
respectively, the probability of C12 disconnection is relatively large. it is a
signal that the CPU gives to audio. The iPhone big
audio IC doesn't need to replace the new one, just
re-weld tin to old one.
Install the iPhone, and press the iPhone power button, now the iPhone 7 can be turn on smoothly, the problem has been solved！
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