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iPhone display circuit repairing

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This lesson mainly explains how to check the iPhone 11 display circuit diagram,

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and how to find the measurement point in the real object

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After learning the working principle of the display circuit, we know that

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if there is an abnormal working condition,

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it will cause the display power supply to fail to output plus or minus 5.7V power supply

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Let's find the working conditions of the display power supply

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Step 1, open the component map and bitmap of iPhone 11

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Step 2, determine the position number of the display power supply in the bitmap

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Step 3, go to the schematic diagram to search for the position number,

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and then find the relevant pins according to the signal identification in the schematic diagram

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Step 4, jump to the bitmap according to the signal name in the schematic diagram,

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and the yellow points in the bitmap can be measured

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First open the component map,

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schematic diagram and bitmap of iPhone 11

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Find the display power supply in the component map,

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and determine the position number of the display power supply in the bitmap, U5500

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Then search for the position number in the schematic diagram

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After finding the display power supply, find the working conditions

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of the display power supply according to the functional circuit diagram

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In actual maintenance, the power supply of the display power supply is generally not a problem,

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and sometimes there is a problem with the boost inductor

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Let's first find the boost inductor

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As can be seen in the schematic diagram,

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the D1 pin of the display power supply is the main power supply

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The main power supply is connected to the inductor L5500,

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which is the boost inductor

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We can jump to the bitmap according to the position number of the inductor or the name of the power supply

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

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Let's find the reset signal

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According to the logo in the schematic diagram,

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it shows that C2 pin of the power supply is the reset signal

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The reset signal of the iPhone 11 is connected to the 1.8V power supply after passing through the node

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Jump to the bitmap according to the name,

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we can see that the power supply of this road will be connected with the CPU power supply

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If there is a problem with this power supply,

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it will cause the machine to fail to boot

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Let's find the I2C bus

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According to the English logo in the schematic diagram,

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the D3 and D2 pins of the chip are the I2C buses

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Jump to the bitmap according to the name,

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we can see that the bus is also used by other chips

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D2 is bus data

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The data bus will be connected to the CPU through the fuse resistor R5500

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Jump to the bitmap according to the name,

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the yellow points in the bitmap can measure the voltage and the resistance of I2C data

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Let's find the 6V boost power supply

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According to the English logo,

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the B3 and B4 pins of the display power supply are 6V boost power supply

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Jump to the bitmap according to the name,

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the capacitor position in the bitmap can measure the boost power supply

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Let's find the display power supply CP and CN conversion voltage

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According to the English logo, it shows that the C4 pin is CP,

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the positive 5.7V conversion pin,

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E4 is CN, the negative 5.7V conversion pin

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Jump to the bitmap according to the name,

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the yellow point can measure the positive 5.7V power supply

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C5500 is a coupling capacitor

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We don't need to measure the negative voltage

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The diode value can be measured at the yellow point position

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Let's find the PWR_EN signal and plus and minus 5.7 pins

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When repairing the display power supply circuit,

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these two signals do not need to be measured

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Because when we measure the display connector, we have already measured the signals

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According to the English logo,

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it shows that the C3 pin of the power supply is the PWR_EN signal

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

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the signal is connected to the display power supply

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and the main power supply by the display screen through the fuse resistor

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Positive and negative 5.7V power supply of the display

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According to the English logo, at the far right of the display power supply

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Jump to the bitmap according to the power supply name,

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the yellow point position can measure the negative 5.7V power supply

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Jump to the bitmap according to the power supply name,

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the yellow point position can measure the positive 5.7V power supply

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When measuring the two power supplies,

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you need to buckle the screen cable to measure the voltage

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Let's find the ADCMUX signal

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According to the English logo in the schematic diagram,

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it shows that the E1 pin of the power supply is the ADCMUX signal

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Jump to the bitmap by the name

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In the bitmap, the signal can be measured at the position of the capacitor C3074

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In this way, we have searched all the working conditions of the display power supply

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Ok, that's it for this lesson