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This lesson is about finding the circuit of the trigger protection in the circuit diagram

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As we learned earlier,

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the trigger protection is caused by the short circuit of the power output to the CPU,

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temporary storage, and hard disk

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Let's open Xinzhizao maintenance system,

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

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How can we quickly find the power supply of CPU,

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temporary storage, and hard disk?

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Let's find the CPU first

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The fastest way is to find the component map first

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There are labels on the component map

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For example, in this position, the U3100 chip is the CPU

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We open the circuit diagram and enter U3100 in the search bar

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to find the description of the CPU in the circuit diagram

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Here is the U3100-2, this is the description of some signals,

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it is not the power supply we are looking for

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We click to find the next one,

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this is not the power supply description

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We continued to find it,

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and when we find U3100-1,

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the label begins with VREG refers to the power supply

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Let's take a look, which pin of the CPU it goes to,

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and who supplies power to the CPU

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Of course, it is generally a power chip

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We can find which power chip supplies power to the CPU

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U3100-1, U3100-7

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These are the descriptions of the power supply of the CPU

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Let's see if it has any other power supply descriptions in other locations

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U3100-8 is the CPU power supply,

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and U3100-9 is also the CPU power supply

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Let's go back to the location U3100-7 we just found,

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let's take a look at the power supply of the CPU

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What is the purpose of finding the power supply?

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First, how many power supplies are there,

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and second, which power chip is the power supply of the CPU from?

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Because the power supply of the CPU is provided by the power chip

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In a mobile phone mainboard, there is more than one power chip,

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and there may be multiple power chips

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Let's take a look

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For example, this VREG_0P75,

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it is a 0.75 volts power supply

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Let's see which power chip it comes from

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Let's first look at how many power supplies the CPU has

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We want to find the ones that are not repeated

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For example, here, U3100-1,

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we can see that there are 6 power supply descriptions here

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The power supply of the CPU in this page is the 11th description

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Here are S6A, S6C, 13 lines

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We see S7C, line 14, and here, 15, 16, 17, 18

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In the process of looking up its power supply,

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we will find that it is on the description of the power supply

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Maybe what we looked for in the front and what we looked for in the back will be repeated,

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because it is divided into pages to describe the power supply of the CPU

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For the power supply here,

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we don't need to know how many channels it has

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When we are repairing, as long as we measure every power supply,

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don't miss any power supply

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That is, when we search the circuit diagram,

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we find that it is very troublesome and repeated

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It has the same power supply in different page numbers

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In this case, we can check the drawings

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We need to find out how many channels of power supply this CPU has

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We first find the CPU,

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and then see which ones on the CPU are power supplies

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The labels that begin with V or VREG are the power supplies

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Ok, that's it for this lesson