If your iPhone 6 touch screen lost control
and opens APP automatically, please believed that you are not alone. Many iPhone
6 users are reporting the lost control of touch screen to us. Now, vipprog took a case to show how to solve the problem
This iPhone 6 has been repair by others and
it replaced the screen assembly, iPhone touch controlchip and touch process chip.
Firstly, power on and enter the system to
test, the touch screen still lost control and open each APP automatically. In
general, disturbance to touch chip or unstable power supply cause such
problems. Use oscilloscope to measure
PN5V7_SAGE, PN5V7_SAGE_AVDDH, PP5V1_GRAPE_VDDH and PP1V8_GRAPE on touch control
chip and touch process chip, finding the voltage is stable, as shown in picture 1-1 and 1-2.
1-1
1-2
The real location of touch control chip
U2401 and touch process chip U2402 is shown in picture 1-3.
1-3
Measure the diode data between the touch
screen socket interface and touch process chip U2402, finding it is normal. The
material object of touch screen socket is shown in picture 1-4.
1-4
Measure the diode data of two ends of
coupling capacitors that is used to communicate between touch control chip
U2401 and touch process chip U2402. These coupling capacitors’ circuit diagram is shown in picture 1-5. The
material object is shown in picture 1-6.
1-5
1-6
The working condition of touch chip is
normal, but why the touch function is not normal?
Does the touch process chip that previous
replaced not work properly? According to the repair experience before, the
problems of touch control chip will lead to the failed usage of touch function.
While the problems of touch process chip will lead to partly failed usage,
vertical bar of touch function. Although the later case have not been met, we
still doubt about the touch process chip is abnormal. Replace the touch process
chip and the problem is still the same. Exclude the abnormal working condition
of touch process chip and touch process chip’s damage, leaving the only
possibility of the disturbance to HF signal. The assistant NFC chip beside
touch process chip is very likely to disturb it, as shown in picture 1-7. The
assistant NFC chip has HF signal output. If it is damaged, it will affect the
normal work of touch chips.
1-7
Finally, remove the assistant NFC chip and
power on, finding the touch function can be used normally, which we can be sure
it is the assistant NFC chip that causes the problem. Replace a fine assistant
NFC chip and the iPhone 6 has been repaired, the touch screen can back to
normal work.
Comments
Post a Comment