The easiest way to find out if the VGA port on your computer's graphic card supports television signal output is to check the graphics card user guide. If it's supported, the function will be listed in the product specifications. You can also check a computer's property settings.
Right-click the desktop. Select "Personalize" from the shortcut menu.
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Click "Display" in the left window panel.
Click "Change Display Settings." Click "Advanced Settings." Click on the tab designated for your computer's graphics card. Look at options available in the display settings. If you can change the VGA output to NTSC, ATSC or PAL, your graphics card supports TV output through the VGA port. If such options are not available, your graphics card likely does not. Refer to the graphics card user guide to definitively determine if the VGA port supports TV out.