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iPhone display circuit repairing

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This video mainly explains the working principle of the display circuit

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of iPhone 6 to iPhone 8, XR, and 11 models using LCD screens

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Their working principles are the same, but the wiring pins are different

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Working principles

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step 1

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When the trigger is turned on,

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the main power supply will output more than 30 channels of power supplies

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There will be 1.8V power supply, first provide power for the display

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step 2

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After the CPU working condition is normal,

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the CPU will read the display data through the I2C bus

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step 3

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After the CPU self-test is completed, when the display circuit is started,

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it will output a reset signal to the display to provide working conditions for the display

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Step 4

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After the display has power supply, passed the I2C test, and has a reset signal,

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it will send a PWR_EN power-on signal for the display power supply

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This signal is sent by the display

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Step 5

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After the display power supply has the PWR_EN signal,

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it will output positive and negative 5.7V power supply for the display screen

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Step 6

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The display has a 1.8V power supply,

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after the reset signal and plus or minus 5.7V,

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all the working conditions of the display have been met

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At this time, the CPU will send display data to the display screen through the MIPI bus,

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and the display screen will display image information

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If the display does not display,

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it means that the working conditions of the display are not satisfied

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We need to find the power supply of the display,

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reset and MIPI bus and other signals

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PANICB is an anomaly detection signal

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If the signal is abnormal,

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it will cause the domestic screen to be displayed in the early mainboard,

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but the original screen will not be displayed

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Ok, that's it for this lesson