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In this lesson, let's learn the analysis and maintenance about the power line infinity ground value

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After finding the touch connector, we find out where the power supply of the touch is

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The touch power supply is VREG_L2C_1P8, TP_3P3,

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1.8V and 3.3V power supply

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Pin 59 is the 3.3 V power supply, Pin 57 is the 1.8 V power supply

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We switch to the bitmap

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Right-click the mouse, click to find the bitmap component

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In this way, you can find the specific pins on the corresponding object

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Let's see where the power is

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Pin 57 is the 1.8 V power supply for touch

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Through this line, you can know which chip the 1.8V power supply comes from

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After we click on the 1.8V power supply, the yellow color here is highlighted

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It goes to the chip U4700

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In other words, this power supply comes from the chip U4700

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According to the appearance features of the chip,

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it is surrounded by many large inductors

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It is a power chip

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The 1.8V power supply of the touch comes from pin 80 of the power chip,

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which is directly supplied to pin 57 of the connector J6503

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When there is an abnormal ground value on this line, how should we analyze it?

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There are usually several situations where the ground value is abnormal

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Infinity appears in the ground value, how should we analyze it?

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Take this mobile phone as an example

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The red marker of the multimeter is grounded, and the black marker is placed on this pin

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The measured value is OL, indicating that this line has an open circuit

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The reference value given on the drawing is 528

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Because this line is only connected to the power chip,

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so when the value is OL, we must first look at the appearance

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Has this connector been moved by others, resulting in false soldering of the pins?

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this is the first case

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If the pin is soldered falsely, it is necessary to re-solder the connector

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If the pins are not soldered falsely, the connector is complete and untouched,

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but the value is infinite

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Because this line is directly connected to the power chip U4700,

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so we need to re-solder the power chip

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If the value is still infinite after re-soldering, we need to remove the power chip

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After removing the power chip, place one of the marker of the multimeter in this position

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and the other in this position to measure the continuity and see if the lines are connected.

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If the circuit is connected, it will display a value of 0,

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then directly replace the U4700 power chip

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Measure the value from pin 80 of the power chip to the pin 57 of the connector

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If OL appears, it means that the line is broken

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We need to fly a wire to connect these two pins

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Well, this is how to analyze the ground value infinity

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That's all for this lesson