iphone7 screen does not display

Received a iPhone7 from one of our customers. The fault described is that it can enter the system and the customer can hear the message voice, but the iPhone screen does not show anything but black. As shown in picture 1.

Pic 1


Connect the adjustable DC power supply, the current shows all normal, and it also respond when connect it to the computer.

Disassemble the iPhone 7 motherboard to measure the basic conditions of the display function by Fluke digital multimeter, it's measured that the seventh pin PP_1V8 of  touch socket(J4502) display power supply at infinite value, now the fault is found.

Pic 2


The power supply is changed from PP_1V8 to PP1V8_LCM_CONN by inductor FL3906 conversion. The end of the inductor has resistance value, and the other end has no value, so we judge it's FL3906 damage.

Connect the jumper wire as shown in picture 3.

Pic 3


Failure is repaired successfully!

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