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iPhone display circuit repairing

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This video mainly explains how to find the working conditions of the display power supply

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of the iPhone XR model and how to find the measurement points

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Step 1, find the position number of the display power supply in the XR component map

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

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Step 3, according to the schematic diagram,

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find the corresponding signal in the schematic diagram

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Step 4, jump to the bitmap according to the English logo in the schematic diagram

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In the bitmap, the yellow point position can measure the voltage and the diode value

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Open the component map, circuit diagram, and bitmap of the iPhone XR

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In the component map, find the position number of the display power supply,

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and search for it in the schematic diagram

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After searching, find the corresponding signal according to the circuit diagram

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First find the main power supply and boost inductor

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According to the logo in the schematic diagram,

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the D1 pin is the display power supply, and the L5500 is the boost inductor

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In actual maintenance, the main power supply will not cause problems

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

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and the display power supply cannot be repaired

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When L5500 is measuring, we can jump to the bitmap according to the position number

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We can see the inductor measurement point

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

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According to the logos in the schematic diagram,

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the C2 pin is the reset signal

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The reset signal is connected to the 1.8V power supply through the connection point XW5501

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Jump to the bitmap according to the name,

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you can see that the 1.8V power supply will be connected to the CPU, Wifi and other chips

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There will be no problem with this power supply

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If there is a problem, it will cause the machine to fail to boot

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During the actual maintenance, the board layer may be disconnected,

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resulting in no reset signal of the display power supply

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Let's find the I2C bus

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According to the logos, the D3 and D2 pins of the display power supply are the I2C buses,

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and the I2C buses are sent by the CPU

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Jump to the bitmap according to the name,

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

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The I2C bus data pin is connected to the CPU through the resistor R5500

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Jump to the bitmap according to the name,

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we can measure the voltage and diode value on the yellow points in the bitmap

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The I2C bus is shared with other chips, and there are fewer problems

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Let's find the 6V boost power supply of the display power supply

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According to the pin identification,

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the B3 and B4 pins are 6V boost pins

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Jump to the bitmap by the name

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The voltage and diode value of the boost power supply can be measured

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at the position of the yellow point in the bitmap

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Let's find the positive and negative 5.7V power supply conversion signals, CP and CN

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In the schematic diagram, the C4 pin of the power supply is CP,

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the positive 5.7V conversion signal

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E4 pin is CN, negative 5.7V conversion signal

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They are all converted by the coupling capacitor C5500,

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we can only measure the positive 5.7V voltage during measurement

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Jump to the bitmap by the name, and the positive 5.7V voltage can be measured

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at the second pin of the capacitor C5500

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Diode values can also be measured

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Jump to the bitmap by the name, we can measure the diode value of the negative 5.7V power supply

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on the first pin of the capacitor C5500,

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and the voltage cannot be measured

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Let's find the PWR_EN signal and the positive and negative 5.7V power supply

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These two signals do not need to be measured during actual maintenance

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Because when we overhaul the fault of no display,

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we have already measured the signals at the display connector

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In the schematic diagram, the C3 pin of the power supply is the PWR_EN signal

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Jump to the bitmap by the name, this signal is connected to the main power supply

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

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According to the logo,

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it shows that the E3 and E2 pins of the power supply are negative 5.7V power supply

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A3 pin is positive 5.7V power supply

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Jump to the bitmap by the power supply name,

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and the negative 5.7V power supply can be measured at the position of capacitor C5504

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Jump to the bitmap by the name, and the positive 5.7V power supply can be measured

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at the first pin of the capacitor C5502

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When measuring the two power supplies,

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we need to buckle the screen cable to measure the voltage

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Let's find the ADCMUX monitoring signal

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According to the pin identification 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, the signal is sent from the display power supply to the main power supply

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We can measure the voltage and diode value of this signal at the position of the capacitor C2030

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

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Ok, that's all for this video