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How to use the schematic diagram

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In this lesson, we mainly study the meanings of the symbols in the schematic diagram

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The first page of the schematic diagram is generally a catalog page,

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just like a book, there will be a catalog after opening

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This catalog page introduces the circuits covered by the different page numbers

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In the schematic diagram of Apple models, BS represents the screw column,

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and PP, TP, and FD in the schematic diagram refer to the test points

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For example, in the schematic diagram of Xiaomi,

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the test point marks TP1606, TP1607, etc.

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In the schematic diagram of Android machine,

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the power supply line and the signal line are the same thickness

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But in Apple's drawings, thick lines are generally for power supply,

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and thin lines are generally for signals

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But some lines have the same thickness

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At this time, we need to judge whether it is power supply or signal according to the power supply name

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In the schematic diagram, the box represents the chip,

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and the more chip pins, the more boxes there will be

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The position number inside the box is the same, it means the same chip

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Near or below the position number in the schematic diagram refers to the chip model

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For example, CG8889ATT is marked at the bottom of U6200,

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which is the model of this chip

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If the line marks NC or a cross in the schematic diagram,

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it means that the line is not used

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For example, in the drawing, there are several pins marked with NC,

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which means that the pins are empty and unused

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The English logo outside the box in the schematic diagram is the logo of the mobile phone manufacturer

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The internal English logos belong to the chip manufacturer's logos

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In the schematic diagram,

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the numbers and letters at the junction of lines and boxes represent the coordinates of the chip

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Because mobile phone chips are all BGA chips,

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when marking pins, numbers are generally used for horizontal rows,

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and letters are generally used for vertical rows

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Numbers and letters represent the pin coordinates of the chip

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The pin coordinates of the chip in the drawing correspond to the coordinates of the chip in the bitmap

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The arrow at the end of the line in the schematic diagram faces outward,

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or the one marked OUT means that the signal is an output

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For example PM_CLK_IN,

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the arrow pointing outward represents the signal output

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Arrows pointing inward or marked IN represent input,

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such as AUTO_ON, arrows pointing inward

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Then this signal represents the input

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There are arrows or logos on both sides,

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and the representative signal of BI can be input or output

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For example, PM_FAULT,

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there are arrows on both sides of this signal,

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which means that the signal can be input or output

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In the schematic diagram,

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the number at the end of the line means that the signal will reach the page number of the drawing

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The more numbers, the more pages the signal reaches

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Generally, Apple and Vivo models are mostly

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Like in the drawing of this Xiaomi model,

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it has no identification number

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A dot will be marked on the cross-connected lines in the schematic diagram,

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and no dot will be marked on the lines that are not connected

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For example, if there is no dot after the line crosses,

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it means that the two lines are not connected

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If there is a dot, it means that the lines are connected

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Some components in the actual products may not be installed

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It is not to save material, it has a variety of design versions,

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such as high configuration, medium configuration, low configuration

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There are maybe many components that are not installed in the low-end version

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Different manufacturers have different logos

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Apple uses NOSTUFF to identify,

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Huawei uses DNI to identify,

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and Xiaomi uses NM to identify

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If NM is marked next to the component,

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it means that the component is not installed

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OPPO, Meizu and Samsung use NC to identify

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If the component is marked NC,

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it means that the component is not installed

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In the schematic diagram, the English name marks are completely consistent,

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and in the real object it means that they are connected

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Ok, that's it for this lesson