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In this class, we talk about the description of the working conditions

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of the display circuit of the OLED screen in the drawings

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According to its working conditions, let's look at its power supply first

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Here is AVDD_7P6, 7.6V power supply

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There is also a 3 volts power supply and a 1.8 volts power supply

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And the ELVSS here, the -4 volts power supply,

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and the other one is 4.6 volts power supply

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Let's not look at these two, they are touch

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What are we looking for?

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These are all display circuits except the blue ones

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Here, ELVDD is the 4.6 volts power supply

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We see its power going to the socket J6400

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This connector, we can think of it as a display

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Because the connection of the screen is through this connector

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These power supplies or signals are to be given to the display screen

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All of these power supplies are supplied from other chips,

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and the arrows here indicate the direction

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During the power transmission process, there is a 0 ohm resistor

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This 0R means 0 ohm resistance

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In the actual maintenance,

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pay attention to whether it has false welding,

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or corrosion, open circuit

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This 0 ohm resistor can be regarded as a wire

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If there is a problem, we can short it

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When is it shorted?

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It's all chips on this end

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For example, in the pin 31,

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when using the diode gear to measure the ground value,

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if there is an infinity

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we first need to measure this foot to see if it is infinite

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If there is no infinity,

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it means that there is a problem with this 0 ohm resistor

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We can take it off, connect it directly with a wire,

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and connect its two pins together

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ok, this is its power supply

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Next we look at the signal

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This is the reset signal

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The following VDDP_EN is an enable signal

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EL_ON2 is also an enable signal

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We should note that the turn-on signals are all sent by the screen,

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and only when the power supply chip is supplied to the screen

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can it output these power supplies

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There is also an interrupt signal below, ERR_INT_N

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There is also a sync signal, MDP_VSYNC

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There is a detection signal below, LCD_ID_DET

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OK, then to the left,

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here is the bus, which usually starts with DSI on Android phones,

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and D means display

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Then here, LANE refers to the data channel

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The MIPI bus has a characteristic, it all leads to the CPU

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When we fix the no display fault,

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we can find its specific pin and open the bitmap

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For example, we can find the 27 pin line

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We can find this pin with the black test lead of the multimeter

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Measure the ground value from the pin of the socket to see

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if there is any problem with the channel from it to the CPU

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Whether there are components connected in series on the channel,

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whether the components in series have false welding,

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whether there is an open circuit,

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and whether there is a short circuit

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We will talk about these later in the maintenance

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This is the description of the working conditions

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of the OLED screen in the circuit diagram

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Okay, that's all for this lesson