Solution for iPhone Screen Touch Function Failed

If the screen has no touch function, first, replace the new screen, and then test whether the screen touch function is malfunctioning. If there is still no touch function, start to test and repair the motherboard

Example 1: iPhone X has no touch which caused by the abnormal working of the inductor L5600

  1. First, observe the appearance of the motherboard components through a microscope to see if there are signs of rust, mildew, and burnt.
  2. Test the screen interface, the ground resistance, and the voltage of each pin. In this case, the ground resistance of each pin is normal, indicating that there is no problem with the J5800 interface of the base.
  3. Test the touch IC U5600 and the resistance of input and output circuit components to the ground.
  4. After the test, C5650, C5651, and other capacitors are normal to the ground pole value, then it is considered that the fault lies in the inductor L5600 or the Touch IC U5600 fault.
  5. Inductance testing is more difficult and easier to replace. First, replace the inductance. Test after replacing the inductor L5600, the touch function is normal, and the fault is eliminated.
  6. If the problem persists after replacing the inductor, try to continue to replace the U5600.

Example 2:iPhone 7 has no touch function

  1. First, observe the appearance of the motherboard components through a microscope to see if there are signs of rust, mildew, and burnt.
  2. Test return key interface J4502 each pin to ground resistance and voltage
  3. According to the schematic diagram, test the resistance of each pin to the ground, if all of them are normal, it means that the base is not faulty
  4. Power on and test the voltage of each pin, and it is found that there is no voltage on pin 11, and this pin is the PP5V1_TOUCH_VDDH voltage.
  5. It is found through the schematic diagram that this circuit is powered by the display chip U3703 and then connected to the power supply IC U1801.
  6. If the resistance of the test capacitor C3902 to the ground is normal, it is suspected that the chip U3703 is faulty.
  7. After replacing the U3703, install the screen and start the test, the touch is normal, and the fault is eliminated.
  8. If the fault still exists after replacing the display chip, the extension circuit will continue to test the peripheral components in the direction of the power IC U1801.
Repair skills

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