Please check whether the power cord, transformer, extension cord and wall plug connected to the computer are connected correctly, as shown in the figure below. If the extension cord is equipped with a switch, make sure that the switch is on.
Be sure to use the power cord and transformer with correct specifications and factory configuration to connect the power port of the computer.
Try replacing other extension cords and wall plugs to solve the problem.
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2. Confirm the connection mode between the monitor and the display adapter.
Please make sure that the signal line and power line of the external monitor are connected correctly, as shown in the figure below. Please make sure that the external monitor is powered on.
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If the computer is equipped with an independent display adapter, please connect the other end of the external display signal line to the display port corresponding to the independent display adapter on the computer side, as shown in the red box in the figure below.
If the display screen still can't be displayed normally, please output the display through the built-in display port of the motherboard instead (if the motherboard of this model has no built-in display function, please ignore this step). Please remove the independent display adapter first, and connect the signal line of the external display to the display port corresponding to the built-in display on the motherboard, as shown in the green box below. If the independent display adapter is not removed and the external display is connected to the corresponding display port of the built-in display, the display will not be normal. If the connected built-in display port can display normally, it means that the independent display adapter may be abnormal, so please send it for repair as soon as possible.
The above method is also applicable if the computer has an additional external display adapter.
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(Note: The display port of the display adapter changes randomly with different models. )
3.？ Remove external devices
If the problem still cannot be solved, please follow the instructions below to remove all external devices and repeat step 2.
Please remove all USB external devices, including keyboard, mouse, card reader, portable disk and external hard disk.
Please unplug all connected wires, including screen signal wires (HDMI/VGA/DVI) such as network cables and audio cables, and only connect an external monitor first to confirm that the computer can be turned on normally and display the screen.
If the computer's hardware has been upgraded or expanded, including hard disk (HDD), solid state disk (SSD), memory (RAM) or display adapter, please remove the hardware or restore the hardware to the original factory settings.
If the problem still persists, please contact the nearby customer service center to arrange maintenance.