When you press the “Home” button on your iPhone or iPad to unlock it and without warning or notice, the screen goes and STAYS black or blank. You rest your phone for a while and try to ignore it. After about an hour or so, with crossed fingers, you once again push the Home button. But no luck, the black screen continues. The iPhone looks like it’s on and you see a faintly illuminated grid; you’re just not seeing any icons, lock screens. Maybe you think your iPhone is dead and can' t save it. But now vipfix will tell you the reason and solution for you, hoping you can benifit from it.
The customer mentioned the screen was broken last time, after replacing its screen, the iPhone 6 cannot boot.
1. Now, disassemble cell phone and connect it with multimeter for normal standby. Press the power button, the current jumping change is normal and enter into booting state, we can judge the fault is on the display circuit.
2. In accordance with the customer's words, the fault was caused by damaged screw hole when installing the screen, which results in the display circuit signal disconnection and non display. Then we measure the value on display seat and found that the reset signal is infinite, by the time the screw hole should be repaired with jumper wire. As shown in picture 1-1 and 1-2.
3. After the jumper wire is repaired, turn on the iPhone 6, it can display normally. When the system function is tested, we found that the touch can not be used. The value of the touch synchronization signal is found to be too large when the value is displayed on multimeter, as shown in picture 1-3. The normal sync signal should be about 20 lower than the reset signal, but the secondary level value of this board sync signal is about 10 larger than the reset signal.
4. With the bitmap synchronization signal, there is a test point in the vicinity of the screw hole, it shows normal value on the test point, directly connect jumper wire from the test point to display seat.
Now booting the iPhone 6 to test, finally the touch is normal. The display fault is solved!