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iPhone touch circuit repairing

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This video mainly explains how to find the iPhone 11 touch circuit signals and measurement points

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Search method step 1,

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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 signal 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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Before looking for the signal, we first open the iPhone 11 component map, schematic 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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First find the 1.8V power supply of the touch screen

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The pin 20 of the touch connector is the 1.8V power supply

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Jump to the bitmap according to the name,

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the 1.8V power supply is connected to the main power supply after passing through the fuse inductor L8100

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Let's find the I2C bus of the touch screen

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Pins 15 and 17 of the touch connector are the I2C buses,

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which are only connected to the measurement points and has no connected components

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In actual maintenance, we do not need to measure these buses

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We mainly look for the pins 12 and 14 I2C buses of the touch connector

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Pin 12 is the I2C bus clock

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Jump to the bitmap according to the name, the bus clock signal is directly connected to the CPU

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Pin 14 is the bus data pin

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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 R8156

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

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Because the screens and data storage chip of the iPhone XR and 11 series are all on the touch cables

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Therefore, when the CPU wants to read the screen data,

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it can only read it through the I2C bus of the touch cable

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

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Let's find the 32KHz clock signal of the touch screen

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The first pin of the touch connector is a 32KHz clock signal

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Jump to the bitmap according to the name,

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the clock signal is connected to the main power supply after passing through the fuse resistor R8103

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Let's find the reset signal of the touch screen

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The 13th pin of the touch connector is the reset signal

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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 inductor L8108

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Let's find the SPI bus of the touch screen

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The SPI bus has 4 lines, and the second pin 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 first passes through the fuse resistor R8172,

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connects to the fuse resistor R1402, and then connects to the CPU,

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the SPI bus clock will be connected to the CPU through two fuse resistors

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The 4th pin of the touch connector is the SPI bus data input

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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 R8174

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The 6th 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 is connected to the CPU after passing through the fuse inductor L8107

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The 8th pin of the touch connector is the 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 L8106

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Let's find the 5.1V power supply of the touch screen

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Pin 18 of the touch connector is the 5.1V power supply

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Jump to the bitmap according to the name,

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the 5.1V power supply passes through the fuse inductor L8101 and then connects to the display power supply

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Let's find the interrupt signal of the touch screen

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The 9th pin of the touch connector is an interrupt signal

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Jump to the bitmap according to the name,

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the interrupt signal is connected to the CPU after passing through the fuse inductor L8105

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In this way, we have searched all the main signals of the touch circuit

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Let's find other detection signals

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MANY_SCAN, forced synchronization signal

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The pin 11 of the touch connector is the forced synchronization signal

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Jump to the bitmap according to the name,

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the signal is connected to the main power supply, camera power supply,

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baseband power supply and other chips after passing through the fuse inductor L8104

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Let's find the data clear signal of the touch

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The 5th pin of the touch connector is the data clear signal

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Jump to the bitmap according to the name,

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the signal is connected to the CPU after passing through the fuse inductor L8103

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Let's find the clock detection signal from the CPU to the touch screen

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Pin 7 of the touch connector is the clock detection signal from the CPU to the touch screen

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Jump to the bitmap according to the name,

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the clock detection signal is connected to the CPU after passing through the inductor L8102

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Let's find the UART bus from the CPU to the touch screen

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Pin 19 of the touch connector is the UART bus emission

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Jump to the bitmap according to the name,

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the emission pin is connected to the CPU after passing through the fuse inductor L8111

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Pin 10 of the touch connector is the receiving pin of the UART bus

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Jump to the bitmap according to the name,

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and the receiving signal is connected to the CPU after passing through the fuse inductor L8110

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In this way, we have searched all the signals of the touch circuits

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Ok, that's all for this video