iPhone touch circuit repairing

This video mainly explains how to find the touch circuit signals and measurement points of iPhone 12 and 12Pro

Search method step 1, find the position number of the touch connector in the component map

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

Step 3, find the corresponding signals in the circuit diagram

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

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

When searching for signals, open the iPhone 12 and 12 Pro component map, schematic diagram, and bitmap

Find the touch connector in the component map

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

After finding the touch connector, find the corresponding signals

First look for two 1.8V power supplies for the touch screen

The pin 15 of the touch connector is the 1.8V_IO power supply

Jump to the bitmap according to the name,

the 1.8V_IO power supply is directly connected to the main power supply,

and is the same as the power supply of CPU, camera power supply and other chips

The first pin of the touch connector is the 1.8V_TOUCH power supply

Jump to the bitmap according to the name,

this power supply is also directly connected to the main power supply, without fuse in the middle

Let's find the I2C bus from the CPU to the touch screen

This group of I2C buses is used by the CPU to read the data in the screen data storage chip on the touch cable

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

The 9th pin of the touch connector is the I2C data pin

Jump to the bitmap according to the name, and the data pin is directly connected to the CPU

Pin 11 is the I2C clock pin

Jump to the bitmap according to the name, the clock pin is also directly connected to the CPU,

without fuse in the middle

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

The pin 17 of the touch connector is a 32KHz clock signal

Jump to the bitmap according to the name,

the signal is connected to the main power supply after passing through the fuse resistor R1601

Let's find the reset signal of the touch screen

The 10th pin of the touch connector is the reset signal of the touch screen

Jump to the bitmap according to the name,

the reset signal is directly connected to the CPU, without fuse in the middle

Let's find the SPI data bus from the CPU to the touch screen

The SPI bus has 4 lines

The 6th pin of the touch connector is the data output of the SPI bus

Jump to the bitmap according to the name,

the data output pin is directly connected to the CPU, without fuse in the middle

The 14th pin of the touch screen is the data input

Jump to the bitmap according to the name,

the data input pin is also directly connected to the CPU, without fuse in the middle

The 16th pin of the touch connector is the SPI bus chip selection pin

Jump to the bitmap according to the name,

the chip selection signal is also directly connected to the CPU

The 18th pin of the touch connector is the clock pin of the SPI bus

Jump to the bitmap according to the name,

the clock signal is connected to the CPU after passing through the fuse resistor R1401

Ok, that's all for this video