FREE GUIDE: iPhone 6 LCD screen display Issue

We received an iPhone 6, the fault described is that the function of iPhone is normal, just the iPhone LCD screen sometimes display, but sometimes not display. Turn on iPhone 6 to test, the iPhone LCD screen doesn't display. Disassemble the iPhone motherboard, and observe it under the Stereo Zoom Microscope, we found there are many solder paste on iPhone display socket and iPhone touch socket. Picture 20-9-1



Is the iPhone LCD screen not display because the socket is not clean? First we use BGA clean water to clean the iPhone motherboard. Because the customer said that iPhone LCD screen also is half bright and half the screen black state, so, after cleaning, we can use digital multimeter to measure the grounding resistance value for the J2019 display socket 1 pin PP_LCM_BL_CAT2_CONN and 4 pin PP_LCM_BL_CAT1_CONN, these two pins will cause iPhone screen half bright and half black problem. We found the resistance value of 4 pin is 2111, which is abnormal, the normal resistance value is about 570. Picture 20-9-2



After a short connection of the FL2025 fuse inductor, the resistance tested is normal.
Picture 20-9-3



Assemble the iPhone display screen and test it, the Apple logo can be displayed normally, but the backlight still not bright. We noticed that the CPU shield cover was been moved, remove the CPU shield cover, we found the CPU was been repaired. Now, it's easy to explain, the U1502 backlight IC is virtual welded when blowing the CPU by QUICK 861DW hot air rework station, and it leads the iPhone LCD screen sometimes bright and sometimes not. Also, there are many solder paste and tin balls, which is easy cause iPhone motherboard to short circuit. Picture 20-9-4



Clean up the tin balls and solder paste, and then remove the iPhone backlight IC. There is a good way to remove the iPhone backlight IC, remove the three filter capacitors above the backlight IC, and then the iPhone backlight IC is easy to remove. Picture 20-9-5


Reballing tin and then install the chip, assemble the iPhone and test it, the fault has been solved.

Tips: For more details about Low price and high quality equipment and phone repair kit, please check the website www.vipprogrammer.com

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