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In this class, we will talk about the direct circuits that cause the OLED screen not to display

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This is a display connector, we can think it as a screen,

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because the screen is connected to the mainboard through a cable

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After the phone is turned on,

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the power chip provides power and outputs a 1.8 volts to the screen

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It outputs a power supply to the LDO,

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which is stepped down by the LDO and converted to output a 3V

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The CPU detects the screen, resets the screen,

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and then feeds back data through the DSI bus

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After the screen is detected,

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it will output a turn-on signal to the display chip

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The display chip will output 3 channels of power supply to the display,

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AVDD, ELVDD, ELVSS

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At this time,

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the CPU transmits the image data to the display screen through the DSI bus,

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and the display screen displays the image

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This is the general process of OLED screen work

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OLED screen does not display and which lines are directly related?

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First, the power chip

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For example, there is a problem with it itself,

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and it cannot provide a 1.8 volts of power

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Second, the display chip

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This display chip refers to a display power supply chip

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There is a problem with the display power supply chip itself,

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it does not work, it will not output the 3-way power supplies,

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then the display screen can not be displayed

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This is the possibility of the power supply chip

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Another possibility is the LDO

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The LDO chip steps down the power supply of 3.5 to 4 volts,

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converts the output to the screen,

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and the output is smaller than the input

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It is a step-down module

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If this LDO module is damaged,

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it will also cause the screen not to display

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Another possibility is the CPU

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In general, we don't consider the CPU,

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so, when will we consider it?

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For example, this mobile phone has been repaired many times,

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and the CPU of this mobile phone is often soldered

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We can know by measuring these signals and lines

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The mobile phone has not been repaired,

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but it has been seriously dropped,

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and the position of the heavy drop is within the welding range of the CPU,

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we must consider the CPU

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If the position of the heavy fall is not within the welding range of the CPU,

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The mainboard is not deformed or crushed

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We do not consider it

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Xiaomi Black Shark, Xiaomi 11 series mobile phones have common problems,

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and there are many CPU false welding

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When the mobile phone with 888 CPU is not turned on,

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we only consider the CPU,

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otherwise we generally do not consider it

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Display connector, when should we consider it?

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When this seat is corroded by water and has poor contact,

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we only need to consider it

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Because this connector has only one function,

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it only conducts power or signals, it is not a chip

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If it is not corroded by water, has not been repaired,

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and has not been deformed,

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it means that it is absolutely no problem,

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then we should not move this connector

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This is the direct circuit that related to the no dislay fault of the OLED screen

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Okay, that's it for this lesson