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iPhone touch circuit repairing

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This video mainly explains how to find the touch circuit signals

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and the measurement points of iPhone 11 Pro and Promax models

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Search method step 1, find the position number of the touch 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, find the corresponding signals in the circuit diagram

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Step 4, jump to the bitmap according to the pins, and view the connected components

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We can measure the voltage and diode value at the yellow points in the bitmap

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When checking the diagrams, we first open the iPhone 11 Pro, Promax component map, circuit diagram and bitmap

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Find the touch connector in the component map

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Search for the position number of the touch connector in the schematic diagram

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After finding the touch connector, find the corresponding signals

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Let's find the 1.8V power supply of the touch screen first

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Pin 20 of the touch connector is the 1.8V power supply

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In the bitmap, the signal name is missing the mark CONN

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So we select the previous signal and jump to the bitmap

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The 1.8V power supply is directly connected to the main power supply without fuse in the middle

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Let's find the I2C bus of the touch screen

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Pins 13 and 16 of the touch connector are the touch I2C buses

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They are only connected to the pull-down resistors in the bitmap,

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and no other components are connected

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In actual maintenance, we don't need to search for the touch I2C bus,

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we mainly search for the I2C bus clock and bus data

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The 7th pin of the touch connector is the I2C bus clock

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Jump to the bitmap according to the name,

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the bus clock is directly connected to the CPU

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The 8th pin of the touch connector is bus data

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Jump to the bitmap according to the name,

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the bus data is connected to the CPU after passing through the fuse resistor R8120

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This bus is used for the CPU to read the screen data storage chip on the touch cable

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Because from iPhone X to 11 Promax models,

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the screen storage chip is installed on the touch cable

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When the CPU wants to read the screen data,

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it needs to read by the touch connector

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If the CPU cannot read the screen data, it will prompt that the screen is not original

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Let's find the clock signal of the touch screen

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The pin 11 of the touch connector is the touch clock signal

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Jump to the bitmap according to the name,

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the 32KHz clock signal is connected to the main power supply after passing through the fuse resistor R8101

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Let's find the reset signal of the touch screen

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Pin 5 of the display connector is the reset of the touch screen

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Jump to the bitmap according to the name,

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the reset signal is connected to the CPU after passing through the fuse resistor R8100

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Let's find the SPI bus

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The SPI bus has 4 lines

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The third pin of the touch connector is SPI bus chip selection

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Jump to the bitmap according to the name,

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the chip selection signal is connected to the CPU after passing through the fuse resistor R8106

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The pin 15 of the touch connector is the SPI bus clock

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Jump to the bitmap according to the name,

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the bus clock is first connected to the fuse resistor R8107,

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connected to the fuse resistor R1402 and then connected to the CPU

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The SPI bus clock is connected to the CPU through two fuse resistors

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The second pin of the touch connector is the SPI bus data output

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Jump to the bitmap according to the name,

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the data output pin is connected to the CPU after passing through the fuse resistor R8110

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The 10th pin of the touch connector is the data input of the SPI bus

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Jump to the bitmap according to the name,

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the data input is connected to the CPU after passing through the fuse resistor R8109

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Ok, that's it for this lesson