iPhone 6 no backlight

Максим Исаев
Reading time: 3 min
190

Первичная диагностика iPhone 6.

After a third-party service, the client brought the iPhone to Bgacenter with a malfunction – it won’t turn on. The display module was replaced in the phone and after that the phone stopped turning on.

We performed initial diagnostics to identify the fault by connecting the phone to the lab power supply (LPS) and checking the Board for a short circuit. Short circuit in the Board is not revealed.

After that, the iPhone 6 was turned on by pressing the Power button (the phone is still connected to an external power source). The smartphone turned on, it became clear from the current consumption on the LPS ammeter. And at the same time the phone has a dark screen: no picture or backlight.

Then we connected test operable display module to the board, turned on the phone and flashed a light on the display. We saw the image on the screen.

This indicates that the backlight on the iPhone 6 board is faulty.

IPhone 6 backlight unit

The backlight unit iPhone 6 consists of:

U1502 – BACKLIGHT DRIVER – iphone 6 backlight controller
D1501 – iphone 6 backlight diode
L1503 – Inductor
С1530, С1531, С1505 – capacitors installed in the PP_LCM_BL_ANODE line

Расположение элементов-подсветки на плате телефона
Расположение элементов-подсветки на плате телефона

iPhone 6 no backlight

Further diagnostics was carried out as follows:

With a multimeter in diode continuity mode, the voltage drop was removed from the connector of the display module J2019.

Расположение элементов-подсветки на плате телефона
Расположение элементов-подсветки на плате телефона
Cняли падение напряжения
Сняли падение напряжения

There was no voltage drop on the first track pin PP_LCM_BL_ANODE_CONN.

Further, following the circuit, we see that the FL2024 filter is installed in this circuit. In order to check the filter for integrity, this filter rang with a multimeter. He turned out to be working.

Линия анода айфон 6
Линия анода айфон 6

Then we determined the location of the elements on the board of the backlight unit and carried out their diagnostics.

D500 Backlight Driver
D500 Backlight Driver

We checked the integrity of the following elements with a multimeter:

  • inductor L1503,
  • diode D1501,
  • capacitors C1530, C1531, C1505

The diode turned out to be faulty.

It was decided to replace the entire backlight unit by taking it from the donor board.

In the photo below you see the prepared pads of the backlight unit.

Контактные площадки блока подсветки
Контактные площадки блока подсветки

After mounting the backlight elements, the board must be checked for a short circuit by connecting to the LPS.

Подсветка айфон 6
Подсветка айфон 6

No short circuit was detected during the check.

We installed the board in the case, connected the display module and turned on the phone.

iPhone 6 turned on with a working backlight.

Проверка айфон 6 после ремонта
Проверка айфон 6 после ремонта

No short circuit was detected during the check.

We installed the board in the case, connected the display module and turned on the phone.

iPhone 6 turned on with a working backlight.

Conclusion

iPhone 6 no backlight is one of the most common repairs of this model. The duration of this repair, along with the diagnosis and disassembly of the phone on average takes 1 hour. We study the repair of the backlight unit of other system boards during the training of soldering at Bgacenter.

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