Today, we are going to fix dead iPhone 7 display screen. The iPhone 7 screen has no display when it is turned on. What causes this? Let's check it step by step.
1. Carefully disassemble the iPhone 7 and disconnect the battery. Put iPhone connect to DC power supply, the boot current is normal, but the display screen still black.
2. Carefully disassemble the display assembly, and replace with new one. Once again put iPhone connect to DC power supply and then power up, the boot current displays normally, but iPhone still goes with no display. So, we suspected that this problem is caused by motherboard backlight circuit broke down.
3. Teardown the iPhone, take out the motherboard. Measuring the grounding resistance value of J4502 with multimeter, the data is normal, which shows that the backlight circuit is also normal.
4. Because the backlight signal is connected directly with backlight IC U3701, now we can judge that the backlight IC U3701 broke down.
5. Paint some BGA Paste Flux, take down the backlight IC with Hot Air Gun at 320 degrees. Now, we need to clean the tins, use soldering iron blow it first, and then use PCB Cleaner to clean it again.
6. Paint some BGA Paste Flux again, align the backlight IC in the correct position, and then solder it with hot air gun. Cooling the motherboard, and then use PCB Cleaner to clean it.
At last, assemble the iPhone well, and then turn on iPhone to test, the white Apple logo appears smoothly. The repairs end!
1. Carefully disassemble the iPhone 7 and disconnect the battery. Put iPhone connect to DC power supply, the boot current is normal, but the display screen still black.
2. Carefully disassemble the display assembly, and replace with new one. Once again put iPhone connect to DC power supply and then power up, the boot current displays normally, but iPhone still goes with no display. So, we suspected that this problem is caused by motherboard backlight circuit broke down.
3. Teardown the iPhone, take out the motherboard. Measuring the grounding resistance value of J4502 with multimeter, the data is normal, which shows that the backlight circuit is also normal.
4. Because the backlight signal is connected directly with backlight IC U3701, now we can judge that the backlight IC U3701 broke down.
5. Paint some BGA Paste Flux, take down the backlight IC with Hot Air Gun at 320 degrees. Now, we need to clean the tins, use soldering iron blow it first, and then use PCB Cleaner to clean it again.
6. Paint some BGA Paste Flux again, align the backlight IC in the correct position, and then solder it with hot air gun. Cooling the motherboard, and then use PCB Cleaner to clean it.
At last, assemble the iPhone well, and then turn on iPhone to test, the white Apple logo appears smoothly. The repairs end!
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