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We continue the lesson with the search of the power supply of the CPU that caused the trigger protection

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After finding the CPU, see which is the power supply of the CPU

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Those begin with V or VREG are all the power supplies

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Let's take a look

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Generally, Xiaomi and Huawei use more than 24 lines,

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and up to 35 lines of power supply

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This is the power supply of the CPU, temporary storage and hard disk together

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I will analyze one of the power supplies for you

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Such as U3100_9, this is the power supply for the CPU, why?

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Because this is a power supply,

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and at the same time it goes to the CPU,

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the CPU itself cannot generate electricity,

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then the power needs to be provided by other chips,

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so we say that this is the power supply of the CPU

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This is the power supply connected to the CPU chip,

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we call it the power supply of the CPU

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Another question is, where does this power come from?

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We double click on it,

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here we go to another part of the CPU, to another chip

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Of course, there is no CPU here, let's ignore it

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This is to U4200, let's see what chip it is

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We found that it was connected to a chip U4200

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The model of the U4200 chip is PM8250,

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and PM8250 is the power chip

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This power supply, VREG_S4A_1P8,

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it is output by the 119 pin of the chip U4200, and then to the CPU

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This is to draw a conclusion that this power supply comes from the power chip

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In the process of supplying this power from the power supply to the CPU,

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it will also be supplied to other circuits, or chips on other circuits

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So, now we just look at the line it supplies to the CPU

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For example, it comes from the chip U5800 again

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That is to say,

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this power supply actually has many functions,

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and it needs to supply a lot of chips

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When we fix the trigger protection fault now,

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we can see the line to the CPU

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It leads to a lot of chips, let's not pay attention to it here

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We only find it to go to CPU U3100

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We just found it, it went to CPU U3100

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Then the search method of other power supply is the same, it is the same method

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Let me summarize the search for CPU power supply

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There are many power supplies for the CPU,

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which mainly come from the power supply chip

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There is a problem with the CPU powered lookup

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Second, it has a lot of ways and a lot of groups

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Third, it comes from the power chip

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So how to quickly determine the power supply of the CPU,

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we must pay attention to this

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First, it is a power supply,

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how to see that it is a power supply?

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The labels begin with VREG or V, or begin with VBUCK or VOUT,

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these are the signs of power supply

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Second, the CPU can only accept power

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Third, the power supply connected to the CPU chip,

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which is given to it by the power supply chip,

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which means that this power supply is given to it by other chips

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The power supply is given to it by the power chip,

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and it is regarded as the power supply of the CPU

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Well, this is the introduction to the power supply of the CPU

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Ok, that's it for this lesson