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we talk about how to repair the vote of No Display

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in this lesson

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if we measure the reset

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detection bus there is no problem

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at this time we need to test this

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volts power supply and 3V power supply

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under a power on stage to see if there is any voltage

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turn the multimeters DC voltage gear

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and the black test lead is grounded

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and the red test leads used

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to find the position of the 1.8V power supply

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and the 3V power supply on the Memeboard

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of course the Memeboard must be powered on

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let's Xiaomin 9 Pro as an example

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to see where

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the mailman position of its power supply 1.8

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and 3V are

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1.8V power supply is here pin 3rd one

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V R E G

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out 14 a one P 8

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this is the 1.8 power supply for the screen

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this is the 3V power supply for the screen

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let's test here in the booth states

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let's see where these 1.8V comes from

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it has 2 photographs connected to it

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it comes from the power trip you fall to 0 0

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if we can measure the 1.8V in this place

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then we have to restore the power trip

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or replace the power trip

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after resortering

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we still can't matter this voltage

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at this time we need to buy a new one

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or remove good power trip

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from the disassembly board and replace it

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let's look at 3V power supply

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I'm 35th pin of the display socket J 64 0 0

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VCI 3 P O is the power supply of 3V

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when we test we can test at this position

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there is a condition for this measurement

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the screen of the mobile

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phone should be buckled on the seat

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and then the power on should be triggered

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the 3V power supply comes from this U 64 0 2

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in 64 0 2 steps down the V R E G B O B power supply

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and outputs the 3V power supply to the screen

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at this time if this voltage cannot be married

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we can replace the trip use 64 0 2

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if we don't have this trip

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it's hard to find

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what do we do

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we can also remove the use 64 0 2

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after removing it

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short circuit

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input power supply and the output power supply

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that is connect a wire

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and then test again

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if the display is normal at this time

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it means that there is a problem with the chip

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and it does not work

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causing the 3V power supply to normal output

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well let's summarize

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what if we can't matter the voltage

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when the power is turned down

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first of all make sure

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that there is no problem with measured ground value

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but this voltage cannot be measured

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we can resort the partnership

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after resortering

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if there is still no voltage

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it is time to replace the parkship

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this is the case where 1.8V cannot be measured

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so what about 3V

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it comes from LDO module

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if the ground value is normal

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and the 3V power supply cannot be measured

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we directly replace the chip use 64 0 2

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which is a step down trip

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and the food is usually repaired

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we go to test the game

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the voltage can basically be measured

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okay that's it for this lesson