LG Electronics M4720C, M5520C Troubleshooting, No image is displayed, Key Lock On message appears

Models: M5520C M4720C

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No image is displayed

Is the power cord connected?

Is the power indicator light on?

Power is on, power indicator is Blue but the screen appears extremely dark.

Is the power indicator amber?

Does the 'Out of range' message appear?

Does the 'Check signal cable' message appear?

• See if the power cable is properly connected to the outlet.

• See if the power switch is turned on.

• May need service.

• Adjust brightness and contrast again.

• Backlight may need repair.

• If the set is in power saving mode, move the mouse or press any key.

• Turn both devices off and then back on.

• The signal from the PC (video card) is out of the vertical or horizontal frequency range of the set. Adjust the frequency range by referring to the specifications in this manual.

* Maximum Resolution

RGB : 1920 x 1080 @ 60 Hz

HDMI/DVI : 1920 x 1080 @ 60 Hz

The signal cable between PC and set is not connected. Check the signal cable.

Press INPUT on the remote control to check the input signal.


Did you install the driver?

Install the product driver, which is provided with the product, or download it from the web site. (http://www.lg.com)

See if the plug&play function is supported by referring to the video card user manual.

'Key Lock On' message appears.

The 'Key Lock On' message appears when pressing the Menu button.

The control locking function prevents unintentional OSD setting change due to careless usage. To unlock the controls, simultaneously press the Menu button and

►button for several seconds. (You cannot set this function using the remote control buttons. You can set this function in the product only.)


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LG Electronics M4720C Troubleshooting, No image is displayed, UnknownProductmessageappearswhentheproductisconnected