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In this class, we talk about the maintenance for the power supply of the LCD backlight screen,

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that is, if there is a problem with the power supply, how can we repair it?

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This is the appearance of the screen power supply chip of an LCD backlight screen

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Here's the chip,

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here's a couple of inductors next to it

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Let's take a look at the structure of the power supply circuit of the LCD backlight screen

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First of all, we see that there is a charging chip, a CPU,

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a display chip, that is, a screen power supply chip,

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and a display connector

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The display connector should be regarded as a screen,

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because this power supply is given to the screen,

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and this connector only plays the role of conduction and connection

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The charging chip is the main power supply,

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and this main power supply is available in standby

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Then this is the turn-on signal that the CPU gives to the display chip, ENN and ENP

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EN is on, N is negative voltage,

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ENN is negative voltage enable,

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ENP is positive voltage enable

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Who do they turn on?

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Turn on this chip, let this chip output VSP, and VSN

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This enable has a correspondence, ENN is a negative enable signal

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The CPU must give the screen power supply chip a turn-on signal,

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and its negative voltage can be output

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For the same reason, ENP is also like this,

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it is a positive enable signal

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This EN signal has a voltage, usually 1.8 volts

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During startup, we can measure it

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That is, after we trigger the boot,

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both ENs can be measured 1.8 volts

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Use a multimeter to measure the voltage

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If there is a voltage of 1.8 volts,

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it proves that there is no problem with these two enable signals

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Well, this is the way to judge whether this EN has been issued

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or whether this EN is normal when we repair it

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Let's look at this display chip again

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We can also call it a boost chip,

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it adjusts the voltage of the main power supply,

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and finally outputs two power supplies to the screen,

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one is positive voltage and the other is negative voltage

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There are still some inductors that have not been drawn,

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and there are more than one energy storage inductors

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This is an overall structure of the display power supply of the LCD backlight screen

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Okay, that's it for this lesson