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Introduction

iPhone 8 Plus turns on with black screen. What will you start with? For screen issues, the most common solution is to replace with a new display assembly to see whether it’s a screen problem or a board issue. As for black screen issues, we can also start with the boot current. Run boot current measurement first. If the boot current is normal, then we can confirm that the phone is turning on with no display. As for display issues, find the display connector at the very beginning…

Vidéo d'introduction

  1. Press power button to power on. There is no response from the phone. Measure boot current first. The current reading is normal. Which indicates that the phone is turning on, yet with black screen.
    • Press power button to power on. There is no response from the phone.

    • Measure boot current first. The current reading is normal. Which indicates that the phone is turning on, yet with black screen.

  2. Let's start with the display circuit. Run diode mode measurement of the display connector J5700.
    • Let's start with the display circuit. Run diode mode measurement of the display connector J5700.

    • The measured value of Pin 39 and Pin 45 on J5700 is 0.

    • Refer to Refox – the maintenance drawing and we can see that relevant circuits of the two pins are backlight circuit.

  3. Le kit d'outils Essentiel

    Les outils les plus utiles dans notre kit le plus compact.

    J'achète

    Le kit d'outils Essentiel

    Les outils les plus utiles dans notre kit le plus compact.

    J'achète
  4. Now we need to run further measurement of the two circuits. We can start with R5730 and R5733. The two are Zero Ohm “resistors” that usually act as protective roles on the circuit.
    • Now we need to run further measurement of the two circuits. We can start with R5730 and R5733. The two are Zero Ohm “resistors” that usually act as protective roles on the circuit.

    • For better operating, we have to tear off the shielding paste and remove shielding bracket with Cutting Nipper first.

  5. The measured value of Pin 1 on R5733 is normal and there is no measured value of Pin 2 on R5733, which is abnormal.
    • The measured value of Pin 1 on R5733 is normal and there is no measured value of Pin 2 on R5733, which is abnormal.

    • The measured value of Pin 1 on R5730 is normal and there is no measured value of Pin 2 on R5730, which is also abnormal.

    • Judging by this, R5733 and R5730 have been damaged and we need to replace with new resistors.

  6. Detach R5733 and R5730 from the board with Hot Air Gun.
    • Detach R5733 and R5730 from the board with Hot Air Gun.

    • Clean the bonding pad and solder two new resistors to the board.

  7. Now we can assemble the phone and test.
    • Now we can assemble the phone and test.

    • Press power button to power on. The phone turns on with normal display. Run function test. All going well.

Phryne

Membre depuis le 17/11/2019

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