Share iphone 6 can't connect PC Laptop and show information

1. iphone 6 can't connect PC Laptop and show
information
When iTunes on your computer doesn't recognize your
connected device, you might see nothing of information.
You can follow these steps and try to connect your device
again after each step. You must consider the software and
fix it send repairman. But if you want save money to DIY,
you must use some tools and methods.
Problem:
IPhone 6 cannot connect computer through the USB
cable and i4 assistance software shows no data when
connected, as shown in below picture.
Solution:

2. 1. First we exclude the problem caused by Tail charger
connector. Replace charger connector directly and test,
but the problem still exists. We can sure the charger
connector remains workable. Then we check the circuit
between CPU and the C charger connector. CPU
controller will transfer the circuit. View the circuit
diagram of USB manager U1700 and find its working
condition and data transmission bus, as shown in below
picture.
2. First measure the power supply of PP1V8_SDRAM
and PP3V0_TRISTAR of USB manager U1700 and 5V
power supply of PP_TRISTAR_PIN transferred by
Charge Jack. Find the pin 1 of C1739 of
PP1V8_SDRAM near USB manager U1700 (picture).

3. 3. The material object of C1739 is shown in below
Picture. Measure the power supply of the pin 1 of C1739,
which is 1.8V.
4. The pin 1 of C1700 of PP3V0_TRISTAR near USB
manager is shown in below picture.

4. 5. The material object of C1700 is shown in below
Picture. Measure the power supply of the pin 1 of C1700,
which is 3V.
6. 5V power supply PP_TRISTAR_PIN is the pin 1 of
C1704 near USB manager, as shown in below picture.

5. 7. The material object of C1704 is shown in below
Picture. Measure the power supply of the pin 1 of C1704,
which is 5V.
8. As the power supply of USB manager U1700 is
normal, we replace the USB manage chip first. But the
problem remains the same. Now we measure the diode
data to ground of USB cable bus. The measuring point is

6. shown in below picture and measuring material object is
shown in below Picture. Measure the diode data to
ground of four signals 90_TRISTAR_BI_E75_PAIR
which is used by USB manager to connect Charge Jack,
and the diode data to ground is normal.
9. Measure the diode data to ground of two signals
90_AP_BI_TRISTAR_USB which is used by USB
manager to communicate with CPU, and the diode data
to ground is normal. The measuring point is shown in
below picture and the material object is shown in below
picture, too.

7. 10. Measure the diode data to ground of accessory power
supply PP_E75_TO_TRISTAR_ACCI which is used by
USB Control manager to connect Charge Jack, and the
diode data to ground is infinite. The measuring point is
shown in below picture and the material object is shown

8. in below picture.
11. After checking the PCB bitmap, we know that
PP_E75_TO_TRISTAR_ACCI is connected to inductor
FL1854 which is shown in below picture and material
object is shown in below picture.

9. 12. Measure the two pins of FL1854 and the two pins are
disconnected. Replace FL1854 and measure the diode
data to ground of PP_E75_TO_TRISTAR_ACCI, which
is normal. Assemble the board to Measuring assembly
and turn on iPhone and get into IOS to test. It can be
connected to i4 assistance after insert USB cable.
Trouble is removed.