When iPhone 7 Plus is turned on, but it can't make the phone calls, becasue the iPhone 7P has no service. After check the iPhone, we found it is iPhone baseband CPU porblem, we can fix it.
Check iPhone 7 Plus again, dialing the *#06#, there are no IMEI appears on iPhone display screen. Check
Settings on iPhone, there are IM and Modem Firmware numbers. After reset the iPhone
network settings, the problem still
there.
Open the WUXINJI
Dongle, and then compare with the iPhone
schematic diagram and iPhone motherboard bitmap to measure the iPhone circuit
line power supply. After measurement, all power supply on the iPhone baseband
power tested are normal, we need to re-install the iPhone baseband CPU.
Because it is very close to main CPU, we
need to do a heating insulation for the CPU. Use QUICK 861DW hot air rework station to heat iPhone CPU
for a while, and then use BGA graver to gently remove the glue. We can remove
the inductor on the right side fist and then insert the blade, or we can insert
the blade in the slot，we'd better choose the thin blade. When heated it with hot air gun, we blow
from the side of the CPU to the card slot. When we need to pay it, we can
select a component around the baseband as a reference, and when the tin of
reference begins to melt, we can start to pry into the baseband.
There are many empty on the iPhone baseband
CPU, observe it under the Stereo Zoom Microscope, and then compare it with iPhone bitmap,
there are many pins missing. Apply some lower temperature solder paste on the
solder pad, and then soldering the iPhone baseband CPU with solder paste and
glue, install it to the iPhone motherboard. After the iPhone motherboard is
cooled, use digital multimeter to test whether the peripheral components
short-circuit, so you can determine whether the chip has been installed intact.
Install the iPhone 7 Plus, turn on iPhone, now the signal is back, the service is normal.
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