A customer sent us an iPhone 6 to repair,
the fault described is that the iPhone touch screen is not displayed, but the screen is good
and the iPhone motherboard can also work after the iPhone boot and the button
is normal too.
First use DC power
supply to measure the boot current on iPhone, the
boot current is normal. Tilt the iPhone screen, we can see the Apple LOGO,
which means the iPhone 6 is not no display but without the backlight.
Remove the iPhone motherboard and measure
the resistance of display socket backlight circuit and backlight power supply
by Fluke 15B+ Digital Multimeter, we found the data of backlight power
supply only has 97, but the normal data is more than 400.
Take off the iPhone CPU shield to check the
components near the backlight. After check it under the VGA Camera 7-45X Trinocular Stereo Microscope, it was found that the backlight diode had
been burnt, and the big inductance also is cracked and discolored. In this
case, the elements on the back light path should all be damaged, we need to
remove all components and replace the new.
After replacement, turn on iPhone to test,
now the iPhone screen displays normally, the repairs end!
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