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| {{stub}}
| | Iphone XR display fpc |
| {{Repair Guide
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| |Device=iPhone 11
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| |Affects parts=Motherboard
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| |Needs equipment=Soldering Iron, Hot Air Station, Microscope, Multimeter, Thermal Camera
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| |Type=Soldering
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| |Difficulty=3. Hard
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| }}
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| == Problem description ==
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| Provide a concise description of the issue here. Be as specific as possible to help readers quickly determine whether or not this is the exact problem they are facing.
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| The device turns on and works but there is a dark spot on one of the bottom corners.
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| [[File:Iphone 11 half backlight.jpg|thumb|400x400px|Example of issue iPhone 11 with a dark spot on the left corner]]
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| == Symptoms ==
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| Detail all measurable or observable symptoms in this section.
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| * There is a dark spot on the bottom left side of the screen
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| * There is a dark spot on the bottom right side of the screen
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| === Diagnostic Steps ===
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| The first step is to try to swap parts before assuming there is a problem with the motherboard, so start by trying a new display.
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| If a new display doesn't fix the issue the next step is to diagnose the motherboard.
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| Why this issue even happens in the first place? Well, because on the iPhone 11 motherboard there are actually 2 backlight circuits for the display.
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| Start by taking diode readings of the LCD FPC especially the backlight lines and compare with the image below. If a line that should have 0.500 measures 0.000, you know there is a short. If it measures OL or nothing at all, it means that the circuit is open.
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| [[File:Iphone 11 display fpc.jpg|center|thumb|400x400px|Image FPC Diode readings]]
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| After taking diode readings of the FPC, you will probably already find the line that is faulty, use a program like ZXW to trace where it goes.
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| The backlight circuits are located under a shield on the top board, so if you're skilled enough, you may not need to split the boards.
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| As we said before, there are 2 backlight circuits, so if you have a dark spot on the left side of the screen, you should focus your attention there.
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| [[File:Iphone 11 backlight circuit.jpg|center|thumb|395x395px|iPhone 11 Backlight Circuits]]
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| The most common issue is for the output resistor to be blown, if you already took diode measurements of the FPC you saw that.
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| [[File:Image.jpg|center|thumb|iPhone 11 Backlight Circuit Output Resistors Location]]
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| A common issue is also a short on PP_DISPLAY_BL12_ANODE or PP_DISPLAY_BL34_ANODE, a short on these lines can destroy the entire circuit. Coils, backlight IC, Caps, and diodes.
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| [[File:Blow circuit.jpg|center|thumb|iPhone 11 Blown Backlight Circuit]]
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| Here is also a schematic of how one IC works in detail.
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| [[File:IPhone 11 Backlight Circuit Schematic.png|center|thumb|610x610px|iPhone 11 Backlight Circuit Schematic]]
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| === Repair Steps ===
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| Replacing the output resistors is easy, find them on a donor board or use any with 0.000 ohm resistance and foot size of 0201.
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| The backlight IC U5650 or U5660 is an LM3539A1 and can be easily found.
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| If you have a short on, for example, a capacitor PP_DISPLAY_BL12_ANODE or PP_DISPLAY_BL34_ANODE, it is recommended to remake that circuit.
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