How to Fix iPhone 7 Plus Back-light/Screen Half Black

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Half black screen/backlight problem is common in iPhone 6 Plus, 6s Plus, 7 Plus and 8 Plus, because the backlight circuits of these models have two sets of boost circuits. One boost circuit control left half backlight and the other one control right half backlight. If one set is failed while the other is still working, half of the screen will become black. in this article we will share how to troubleshoot and fix iPhone 7 Plus backlight half black, hope you enjoy our sharing.

Step 1 Function Test

Power on and test the iPhone 7 Plus, half of the screen goes black and the other half lights on normally

Step 2 Diagnosis

Replace a new good screen assembly and test, the display issue still remains after screen replacement, proving it’s not the screen assembly defect caused the half black backlight. Then measure the display connector J4502 pin 37/39/41/43/45/47 diode resistance one by one to check the backlight circuit.

Backlight circuit diode resistance values are measured normal; therefore, we move to measure the backlight voltage at TP0411 and TP0418. As the TP0418 is measured abnormal 4.3V, therefore it’s the defect boost circuit TP0418 caused the display problem.

Step 3 Repairing

Because the backlight circuit diode resistance values are measured normal (no open nor short circuit), so the reasons can cause boost circuit TP0418 defect are backlight IC U4601, backlight diode D4602 or trinity coil IC M2800. We will start with replacing a new backlight IC U4601 and see if this works.

Step 4 Reassemble and Test

Reassemble and power on the iPhone, its display works well, repair completed.

Please refer to below detailed video:

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Tools and Materials Used in This Video:

Microscope

Motherboard fixture

DC power supply

Hot air gun

Tweezers

Solder flux

Rosin

Desoldering braid/solder wick

PCB cleaner

Cleanroom wipes

Multimeter

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