iPhone6 Plus screen does not display repair

Machine model: iPhone6 Plus
Malfunction phenomenon:mobile phoneScreen not displayed
Customer description:
Machine Won’t Turn On, not connected to Connect the power supply’ s brain, was originally turned on screen is black or frozen, even Connect the power supply’ s brain could display the driver, the computer iTunes showed the startup state, and the DUF mode computer iTunes could also be connected. Later, accidentally tweezers hit the backlight boost IC, and two solder joints fell, which made no booting unable to connect to the computer now.

Maintenance process:
The machine only sends the motherboard, and the external DC power supply Connect the power supply has no boot DC power supply 17801 40ma, and DC power supply 16001 DC power supply 17801 is generally the chip connected to the common point VCC circuit PVCCMAN or Capacitor short-circuit current. Press the power button and the current is 110MA or so. If lighting cable is disconnected, there is no response, which is basically judged.

iPhone6 Plus screen does not display repair figure 1.
Backlight IC crystal was smashed, and one Capacitor was lost. In this case, it must be removed directly first. The chip itself is fragile, and it is easy to be damaged by bumping off the corner. Remove the chip directly, and then power on.DC power supply displays 00,short-circuit current troubleshooting. According to the start-up current of more than 70 MA, slowly turn current of change to more than 1A, and see that current change is normal, and there is no display or backlight in the screen connection test, and the original fault is restored.
Now, the boot current is normal and there is no display. Start with displaying VCC, showing that VCC has positive and negative 5.7V touch, 5.1V bootstrap boost and 6V, etc. When the screen is connected for boot measurement, it is found that there is no VCC, and the working conditions of the chip are not met. Let’s change the chip first, in case the chip itself is broken. After changing it on, the amount of VCC is still the same. It doesn’t seem that simple.Check the chip condition. Remove the chip Measuring diode value. The test shows that the B2 angle of IC U1501 has no value, which is normally more than 300.