Today, we are going to repair iPhone 6S
WIFI issue.
The tricky thing about repairing iPhone 6S
WIFI is that you have to use PCIE nand test fixture to re-write the WIFI address after the
replacement of iPhone 6S WIFI module. Some iPhone WIFI still can be used, but
there is a very serious leakage and heat phenomenon, this case can be fixed.
The repair case as follows
After the iPhone 6S boot for a while, it’s
overheating, and then the iPhone suggests the temperature is too high.
Disassemble the iPhone by phone opening
tools, remove the iPhone motherboard, and then connect it to DC power supply to test, after booting for a while(about 10
seconds still not enter the IOS), it shows large current and power down.
According to the above phenomenon, we
suspect that it may be a problem of WIFI(because the current
is normal when you start the boot).
The boot process of iPhone: press the
iPhone power button-- power IC supply power to iPhone CPU/ iPhone Nand flash/ display IC/ light control IC/ touch
IC--CPU start to read the software of Nand flash-- start the WiFi part in 10
seconds-- start the baseband section in 20 seconds to work. Based on this boot
process, we're judging that iPhone WiFi module is damaged.
Because this iPhone 6S can be turned on with iPhone battery and WIFI can be
open after booting, it just overheat caused by large current, and then the
iPhone temperature is too high.
Use rosin method to make WIFI turn white,
and then boot it to test, after a while, the iPhone is seriously overheated.
Disassemble iPhone motherboard, observe the WIFI module under the 7-45X Trinocular Stereo Microscope, it's obviously discolored, which means
the WIFI module is short circuit.
Carefully shovel the shell of the WiFi
module, measure the diode data of all capacitors with Fluke 15B+ DigitalMultimeter, we find a capacitor is short circuit to
grounding. Because there are other components connect with this capacitor, in
order to find the specific short circuit point, we need apply some rosin to turn the parts in the WiFi module
white, and the add voltage on the point of short circuit, after a while, you
will see the short circuit parts discoloration.
After confirm the specific short circuit
point, we can use BGA graver knife to scrape it, after remove this IC, the
iPhone 6S can be used normally.

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