How to fix touch screen not working after water damage on iPhone 6

The iPhone 6 Plus touch screen does not respond after dropping into water and the display and touch screen socket has been replaced. But it’s still not working. What can we do in this case? pls follow the Vipprog to solve it.

The touch screen circuit of iPhone 6S is quite different from that of iPhone 6. The touch control or process chips are all assembled to the display assembly. The display screen and touch screen share the same socket. The material object of iPhone 6S display and touch screen socket is shown in picture 1-1.

 

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When the display and touch chips are assembled at the screen assembly, motherboard only supplies power to touch screen circuit, clock, reset, INT signal and SPI bus. During the repair process, when iPhone has no touch problems and the displays normally after being turned on, we do not have to measure PN5V7_LCM_MESON_AVDDH, PP5V7_MESON_AVDDH and PP5V7_LCM_AVDDH. Because they are shared by display screen and touch screen. The voltage circuit diagram of display and touch screen is shown in picture 1-2.

 

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In general, we just need use multimeter to measure the diode data of part of pins of display and touch screen socket J4200. And measure the voltage of PP5V1_TOUCH_VDDH and PP1V8 after assembling display screen and turning on iPhone. The measuring points are shown as these yellow points in picture 1-3.The diode data and voltage are normal after being measured. Replace the display assembly and measure again, the touch screen still cannot respond.

 

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As iPhone 6S has the 3D touchfunction, the abnormal 3D touch function can cause unresponsive touch screen. 3D touch function is connected to fingerprintsocket. Thus we measure the diode data of fingerprint socket and we find the diode data of reset signal AP_TO_TOUCH_RESET_L is being a little small- just over 80. While the normal one should be about 400. After checking the bitmap, we know the reset signal AP_TO_TOUCH_RESET_L is interlinked with display and touch screen socket, as shown as the yellow poi nts in picture 1-4. But, the diode data of AP_TO_TOUCH_RESET_CONN_L on J4200 is normal. 

 

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Finally, the measurement shows that the AP_TO_TOUCH_RESET_CONN_L on display and touch screen socket on display and touch screen socket is not linked with the AP_TO_TOUCH_RESET_CONN_L on fingerprint socket. Tear up the black adhesive tape on the edge of fingerprint socket and we can see that the several components on the edge of FL4134 and C4134 are corroded. After cleaning the corroded components, turn on iPhone and get into IOS tes t. The touch screen and 3D function can respond normally. The corroded components are shown in bitmap picture 1-5.

 

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