The iPhone 6 Plus got a problem, when we turn on iPhone, the iPhone touch screen has no display, it just keep black, we need to fix it. After checking, we found the iPhone display IC is damaged. The fix details as follows.
Disassemble the iPhone, and then remove the iPhone motherboard, check it under the 7-45X Trinocular Stereo Microscope, we found the iPhone was repaired before. According our repair experience, we think the power supply gets some problem.
Measure the iPhone 6 Plus IC solder pad with Fluke 15B+ digital multimeter , all data is normal.
Install the display chip and buckle the screen to measure, when measure it with DC power supply, the booting current jump is somewhat abnormal.
We can see the backlight behind the screen is bright, the measurement of +5.7V power supply is only about 2.2V, -5.7V has no voltage.
We estimate the display chip internal boost exists problem, and the WUXINJI dongle circuit diagram shows that the capacitor C1554 energy storage booster capacitor is short circuited.
Remove the damaged capacitor by QUICK 861DW Hot Air Rework Station and replace with a good capacitor carefully.
After replacement, the install the iPhone to test. Press the iPhone power button, the iPhone screen can be displayed normally!