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In this class, we talk about the search of CPU and the temporary storage power supply in the bitmap

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Trigger protection is mainly caused by the short circuits of the power output to the CPU,

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temporary storage, and hard disk

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Let's take a look at the lookup of these power supplies in the bitmap

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We open Xinzhizao intelligent maintenance system,

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and open the bitmap, circuit schematic diagram, and component map of Xiaomi 10

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We can directly check the component map

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This is what people who are just getting started can do

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People with basic knowledge can know what the chip does by observing the appearance

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Let's take a look at the U4700,

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the power management written here

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This is on the side of the hard disk

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On the other side, we can see that the position number is U4200,

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which is also the main power chip

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That is, on this mobile phone, it has two power chips

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Ok, we found U4200,

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we first click to the schematic diagram and search for U4200

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But what are we going to find? the output part of its power supply

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Let's keep looking

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Here, we find the U4200-4,

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this is the power it outputs to the outside

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VREG refers to the power supply

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This is on Xiaomi phone, VREG is powered by 1.8 volts

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Right click,

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look for the bitmap signal, it will automatically switch to the bitmap

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Then on this bitmap we can quickly see a phenomenon

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The same line, it will clearly display yellow

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then this shows that the yellow ones are all on the same line

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For example, VREG_S1A_S2A_S3A_0P75 in the lower left corner,

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it is a 0.75 V power supply

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The power supply starts with VREG comes from the chip U4200

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We know that it is a power chip on the component map

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Its power supply goes to L4301, L4302,

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and also to these capacitors

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These yellow highlights are where it leads

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Here it leads to U3100, U3100 is the CPU

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It goes to these pins of the CPU and powers the CPU

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Here we see that there are inductors, capacitors and the CPU

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In actual maintenance,

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generally we can quickly find the power supply of the CPU with only a bitmap

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Let's see how to find

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The periphery of the power chip is generally designed

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to output power from the power supply to the outside

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For example, this is the power chip U4200,

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it has a large inductor around it

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We usually look for large inductors first

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Then one end of the large inductor is connected to the power chip,

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and the other end is connected to the CPU

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We can see at a glance that this is the CPU power supply

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Let's find another way

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Here, the 3 inductors are combined together to power the CPU

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Click on this inductor L4404,

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one end of it is to the power supply,

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this end is the feedback,

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this end is its power supply adjustment,

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here is the output, the output powers the CPU

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This is to supply power to the CPU of the U3100

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Let's take a look at the other way

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This is two inductors in parallel to output a power supply to the U3100

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This line is also the power supply of the CPU,

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it starts with VREG, it is the root output of the power supply,

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and finally leads to U3100

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Then let's take a look at other lines

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For example, in this way, we click on the right side of L4303

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Its power supply is VREG_S4A_1P8

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which is a 1.8 volts power supply

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It can be quickly seen that the power supply of this route comes from the power supply chip U4200,

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which directly leads to the U3100

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The U3100 is the CPU, and its upper layer is the temporary storage

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As long as the power supply to the CPU,

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we can also see it as the power supply to the temporary storage

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Then, let's look at the inductor around it

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This one is also from the power supply,

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and the end of it is not connected to the CPU

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This end of it leads to other chips,

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so this power supply is not the power supply of the CPU

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Let's look at this again

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This end comes from the power supply chip U4200,

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but the other end of it also goes to other chips

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If it doesn't go to U3100,

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it is not the power supply of this chip

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Ok, that's it for this lesson