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iPhone display circuit repairing

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This video mainly explains how to find the iPhone 8P display power lines and measurement points

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Line search method

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Step 1, open the component map of iPhone 8P,

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and find the position number of the display power supply

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

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Step 3, find the signal corresponding to the display power supply in the circuit diagram

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Step 4, jump to the bitmap by the logos,

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the yellow points in the bitmap can be measured for the voltage and diode value

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We first open the component map, circuit diagram, and bitmap of the iPhone 8P

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Find the position number of the display power supply in the component map,

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and search for it in the schematic diagram

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After searching, we look for the corresponding signal

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Find the PP_VDD_MAIN power supply and the boost inductor

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In the schematic diagram,

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it shows that the D1 pin of the power supply is the main power supply,

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and the L5600 is the boost inductor

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The main power supply will not cause problems in the actual maintenance

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If there is a problem that will cause a short circuit fault,

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it will not be able to repair the display circuit fault

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When measuring the inductors,

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we can jump to the bitmap according to the position number

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The inductors can be measured at the position of the yellow point in the bitmap

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Let's look for the reset signal of the display power supply

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According to the pin identification in the schematic diagram,

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the C2 pin is the reset signal of the display power supply

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Jump to the bitmap by the name, you can see that the signal is output by the main power supply,

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and reaches the CPU, USB and display power at the same time

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The power is sent through the resistor R3009

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We can measure the voltage and the resistance of the reset signal at the resistor R3009

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Let's look for the I2C bus

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The I2C bus is sent from the CPU to the display power supply

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In the schematic diagram, the D3 and D2 pins are the I2C bus

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Jump to the bitmap by the names

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We can see that this I2C bus and the I2C bus of other chips are connected together

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We can measure the voltage and diode value of the I2C bus at the resistor R4100

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The bus data pin is connected to the CPU through the resistor R5600

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Jump to the bitmap by the name

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We can measure the voltage and diode value of the first pin of the resistor R1401

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Let's look for the 6V boost power supply of the display power supply

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In the schematic diagram, the B3 and B4 pins of the display power supply

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belong to the 6V boost power supply

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Jump to the bitmap by the name,

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we can measure the voltage and the diode value of the 6V boost power supply on the yellow point in the bitmap

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Let's look for the signal of the display power conversion positive and negative 5.7V

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Among them, CP is a positive 5.7V conversion signal,

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and CN is a negative 5.7V conversion signal

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According to the logos, C4 and E4 pins are the positive

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and negative 5.7V conversion pins of the display power supply

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C5600 is a coupling capacitor,

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and the CP pin is a positive 5.7V power supply

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Jump to the bitmap by the name,

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we can measure the positive 5.7V power supply on the yellow points in the bitmap

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Jump to the bitmap according to the name,

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we can measure the negative 5.7V diode value of the display on the yellow points in the bitmap

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we cannot measure the negative 5.7V voltage at this place

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Let's look for PWR_EN signal and the positive and negative 5.7V of the power output

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These two signals do not need to be measured again in actual maintenance

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Because we repair the no display circuit,

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these two signals have been measured when measuring the display connector

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According to the identification in the schematic diagram,

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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 by the name, we can see that the signal is connected to the display power supply

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and the main power supply by the display through the resistor FL5750

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The E3 and E2 pins of the display power supply supply power to the negative 5.7V of the display,

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and the A3 pin supplies power to the positive 5.7V of the display

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Jump to the bitmap according to the name, in the bitmap,

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the negative 5.7V voltage can be measured at the position of capacitor C5604

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Then jump to the bitmap according to the name,

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the positive 5.7V power supply can be measured at the capacitors C5602 and C5703

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When measuring the positive and negative 5.7V power supply voltage,

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we need to buckle the screen cable to measure it

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Let's find the ADCMUX signal

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

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In the schematic diagram, the E1 pin of the display power supply is ADCMUX signal

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Jump to the bitmap according to the name,

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the position of the capacitor C3070 in the bitmap can measure the voltage and diode value of the signal

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In this way, we complete the search for the signals of the display power supply

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Ok, that's it for this lesson