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iPhone display circuit repairing

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This video mainly explains the signal search method

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and line connection components of the iPhone 8P display circuit

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We know that if a signal in the display circuit is abnormal, it will cause no display

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When repairing, how to find the measurement point,

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how to eliminate the damage to the components after the line is abnormal,

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then you need to find the circuit diagram

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iPhone 8P display circuit search method

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Step 1, first find the position number of the display connector in the component map

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Step 2, search for the position number in the schematic diagram

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Step 3, after searching,

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find the corresponding signal in the circuit diagram

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Step 4, jump to the bitmap according to the signal name,

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and find the line connection components in the bitmap

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When checking the map, first open the component map, bitmap and schematic diagram of the iPhone 8P

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Find the display connector in the component map, and confirm the position number

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Then search for the position number in the circuit diagram

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After finding the display connector,

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search for the signal in the circuit diagram

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Find the 1.8V power supply of the display,

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the 18-pin PP1V8_DISPLAY of the display connector is the 1.8V power supply of the display

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We can see that this pin is filtered by a capacitor

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and connected to the inductor FL5705

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After the inductor, it connects to the main power supply

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Display 1.8V power supply and CPU, hard disk 1.8V power supply is the same way

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During the maintenance,

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there will be no problem with the 1.8V power supply output by the main power supply

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Because if a problem occurs,

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it will cause the CPU and hard disk to have no 1.8V power supply, resulting in no boot

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If the display circuit is abnormal at 1.8V, it is generally the inductance FL5705 is damaged

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Let's find the display's I2C detection bus

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In the schematic diagram,

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the 2nd and 3rd pins of the display seat are marked with I2C_DISP,

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which means that they are the I2C detection buses

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Jump to the bitmap according to the logo

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As can be seen in the bitmap, pin 2 is connected to resistor R5755

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It connects to the backlight chip and CPU after passing through the resistor

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Pin 3 is connected to resistor R5756

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It connects to the backlight chip and CPU after passing through the resistor

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The I2C bus is a detection signal sent by the CPU

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Let's find the reset signal of the display

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In the schematic diagram, the 17th pin of the display seat is for display reset,

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it identifies DISPLAY_RESET

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Select the signal and jump to the bitmap

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We see that the reset signal is connected to the inductor FL5752,

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and then connected to the CPU after passing through the inductor

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Let's look for the PWR_EN power-on signal sent by the display to the display power supply

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The 22nd pin of the display seat is the PWR_EN signal

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Jump to the bitmap by the logo

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It can be seen that the signal is connected to the inductor FL5750

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It connects to the display power supply and the main power supply after passing through the inductor

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Let's find the positive and negative 5.7V power supply of the display

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These two power supplies are sent to the display by the display power supply

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In the schematic diagram, the 20th pin is the 5.7V power supply of the display screen,

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and the 23rd pin is the negative 5.7V power supply of the display screen

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Jump to the bitmap by the name

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The negative 5.7V power supply is connected to the inductor FL5710,

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and after passing through the inductor,

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it is connected to the display power supply U5600

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The positive 5.7V power supply is connected to the inductor FL5700,

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and then connected to the display power supply after passing through the inductor

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Let's find the MIPI data bus from the display to the CPU

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In the schematic diagram, pins 28, 30, 34, 36, 40, 42, 46, 48,

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and pins 31 and 33 of the display seat are marked with MIPI

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It means that these lines are all MIPI data buses

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Jump to the bitmap according to the names

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The MIPI bus will be connected to the CPU through an inductor

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L5750, L5751, L5752, L5733 and L5754 are all inductors connected to MIPI lines,

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and these inductors are all inductors in parallel

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1 and 4 belong to an inductor,

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and 2 and 3 belong to an inductor

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There is no connection relationship between them

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The end of the inductor close to the display seat is connected to the display,

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and the other end of the inductor is connected to the CPU

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Then look for the anomaly detection signal of the display screen

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This signal is sent by the main power supply to the display

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In the schematic diagram, the 16th pin of the display seat is the anomaly detection signal

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Jump to the bitmap by the name, we can see that

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this signal is connected to the resistor R5754

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and after the resistor it's connected to the main power supply

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In this way, all the signals related to the display circuit are searched

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If there is a problem, replace the components connected to the line

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Ok, that's all for this video