Follow this guide to repair Apple iPhone display problems of iPhone 5S. This guide offers you a very detailed logic board repair solution of the problems which iPhone 5S backlight brightness adjustment function is abnormal. If you want to learn more about iPhone logic board repairing guide, follow the more comprehensive version that covered most of the iPhone model visit HERE.
Failure Phenomenon:
After the iPhone 5s dropped into water, the automatic brightness adjustment function was normal, but it was not normal when the brightness is adjusted manually. The brightness was adjusted to about 1/5, and the screen brightness was darkest, and the screen brightness becomes brighter when it was set to the lowest level.
Maintenance Procedures:
In general, this kind of fault was the backlight circuit problem. It was found that the capacitor C131 was loosened when we checked the working conditions of the backlight driving core. The circuit of the capacitor C131 is shown in Pic 1-1. The position of the capacitor C131 on the motherboard is shown in Pic 1-2.
The circuit of the capacitor C131 Pic 1-1
The position of the capacitor C131 on the motherboard Pic 1-2
The capacitor C131 fell by the multimeter pen’s touch and the solder pad on the power supply end under the capacitor also was dropped off. By checking the bitmap, we noticed that the diode D1 connected to the capacitor C131 was just right next to it, as shown in Pic 1-3.
The C131 connecting circuit in bitmap Pic 1-3
We needed to fly a line from a diode D1 cathode to a capacitor C131 positive, as shown in Pic 1-4.
Connecting C131 and D1 by flying line Pic 1-4
Boot test again and the brightness function was back to normal.
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