The next one, iPhone 6, it is a perfect machine, at least i think so, while i have used many models iPhone, but i like this one, only.
Anyway, as a phone repair shop, we need to fix everything we need on phone problems. According to the attached file, we know there happens a flickered faults, so we need to disassemble it and check the IC.
Well, we need to test it again. Connect to the DC power supply, the screen flickering as before described. According to past maintenance experience, the problem of iPhone multi-touch usually resulted from signal interference or unstable touch screen IC power supply.
Use Fluke digital multimeter to test the power of PN5V7_SAGE_AVDDN, PP5V7_SAGE_AVDDH, PP5V1_GRAPE_VDDH on the touch screen controller IC and touch screen processor IC, the voltage is normal.
Then we measure the diode value between the coupling capacitance of the touch screen control U2401 and the touch screen control IC U2402 . It is still normal.
Judging from the customer's description, we conclude that the fault may be related to the replaced touch screen IC itself. According to our experience, touch diseases caused by the touch screen controller IC will cause the touch to not work.
Although a faulty touch screen processor IC will only result in a partial unresponsive touch. Therefore the touch processor may be the faulty part. We remove the touch screen processor IC with YH898D soldering station and replace the new one.
To our surprise, when we test the iPhone after the replacement, the fault still exists. We guess that there is only one type of interference that can cause such touch of the disease - some kind of high frequency signal. The NFC IC next to the touch screen processor is most likely because the high frequency signal it outputs interrupts the normal operation of the touch screen IC.
Next step is to replace and test with the new NFC IC. Great, the fault is cleared thoroughly.
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