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iPhone display circuit repairing

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This video mainly explains how to find the displays power signals and measurement points of the iPhone 12 Promax

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Search method Step 1, find the display power supply in the iPhone 12 Pro Max component map

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Step 2, find the display power supply in the bitmap and confirm the position number

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Step 3, search the position number of the display power supply in the circuit diagram,

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and find the corresponding signal according to the explained schematic diagram

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Step 4, jump to the bitmap according to the position number,

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and find the connected components

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The yellow points in the bitmap can measure the voltage and diode value

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When checking the diagram, we first open the iPhone 12 Pro Max component map,

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circuit diagram and bitmap

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Find the display power supply in the component map,

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confirm the display power supply position number in the bitmap,

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search the position number in the schematic diagram

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After finding the display power supply, find the corresponding signal according to the circuit diagram

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First look for the power supply and boost inductor of the display power supply

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In the schematic diagram, the C7 pin of the display power supply is the power supply pin,

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which is connected to the main power supply PP_VDD_MAIN

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Inductor L9100 and inductor L9110 are power supply boost inductors

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L9100 is used to convert VOUT3,

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and L9110 is used to convert VOUT1

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Let's find the I2C bus that the CPU detects the display power supply

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The D4 pin of the display power is the I2C bus clock

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Jump to the bitmap according to the name,

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the I2C data pin of the power supply is connected to the CPU

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after passing through the insurance resistor R9122

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And it will be connected with the I2C of the display

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Let's find the reset signal of the display power supply

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The D7 pin of the display power supply is a reset signal

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Jump to the bitmap according to the name,

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the reset signal is directly connected to the main power supply

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The reset signals of the display power supply and display screen are the same

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Let's find the turn-on signal sent by the display to the display power supply,

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VOUT1 2_EN and VOUT3_EN

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The D6 pin of the display power supply is VOUT1 2_EN

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Jump to the bitmap according to the name, the turn-on signal is directly connected to the display

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VOUT1 2_EN is used to control the output of VOUT1 and VOUT2

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VOUT1 is 4.6V power supply, and VOUT2 is -7V power supply

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The C5 pin of the display power supply is VOUT3_EN

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Jump to the bitmap according to the name,

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the signal is sent by the display screen

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and reaches the display power supply and the main power supply at the same time

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VOUT3_EN is mainly used to control the output of VOUT3,

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and VOUT3 is 7.3V power suply

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Let's find the inductors that convert the power supply

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Among them, we have already found the boost inductors,

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let's look for the inductors that convert the negative voltage

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The negative step-down inductors of the display power supply are L9130 and L9120

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These two inductors are specially used to convert -7V power supply

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If the inductor is removed, there will be no -7V power supply

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Ok, that's all for this video