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In this class, we will talk about how to repair the power supply of the screen if the voltage cannot be measured

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Let's take Xiaomi 11 as an example,

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if we can't measure the power supply voltage

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For example, this screen has 3 power supply channels,

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this is AVDD,

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this is ELVDD,

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this is ELVSS

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What should we do if we measure it with no problem with ground,

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but no voltage can be measured here?

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Generally, this is caused by chip damage,

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we can just replace the chip directly

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What is the premise for us to replace the chip?

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There is no problem with the ground value of the screen power supply

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Does this seat have any abnormality to the ground value?

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First find the position of these three power supplies on the drawing,

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AVDD, ELVDD, ELVSS

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Find these three points, use the diode gear to measure the ground value

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What is good and what is bad about the ground value?

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A reference value is given on the maintenance inquiry system

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For example, ELVDD, 553,

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if the value we measure is similar to this value, we think it is no problem

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AVDD is marked here with 678, if we measure 600 or 700,

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there is no problem

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ELVSS is marked with -492 here

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We need to pay attention to a problem,

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ELVSS is negative voltage,

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when negative voltage is actually measured, we must pay attention

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A value of 492 can only be measured by measuring with a red pen,

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that is, it must be measured with the red pen of a multimeter,

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so that it can display the normal diode value

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If measured with a black pen,

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it will be close to infinity

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OK, this is how to measure the negative voltage

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When measuring all negative voltages,

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use a red pen to measure

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This is the ground value of the 3 way display power supplies we want to measure

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before replacing the display chip

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Okay, that's it for this lesson