A thin green, yellow, or black line sometimes appears along the edge of a TV screen. This is known as an overscan line. It usually shows up when the TV is set to modes like “Screen Fit” or “Just Scan,” which are designed to show the entire image without cropping. These modes aim to display all available pixels, but if the incoming video lacks data for some edge areas, a colored line may become visible where information is missing.
Main Causes of Overscan Lines
The most common reason for overscan lines is incomplete image data, which is typical when viewing content recorded from live TV broadcasts. Not all channels transmit full pixel information, and the edges may be missing data, causing these lines to appear. Another common reason is a malfunctioning T-Con board, the component that controls how the screen displays pixels. If this board starts failing, irregular colored lines may be seen on the screen.
How to Fix or Minimize the Overscan Line
The simplest solution is to switch the TV’s aspect ratio to 16:9. This setting slightly zooms the image, cropping out the edges and hiding the overscan line. While this may cut off a small portion of the picture—especially when using a laptop via HDMI—it usually does not interfere with normal viewing. If changing the aspect ratio doesn’t help, it’s important to check the resolution and output settings of the connected device. Sometimes the mismatch between the device and TV causes the issue. If the problem still persists, and especially if the line appears consistently across all inputs, it could indicate a faulty T-Con board that may need repair or replacement.
Overscan lines are generally not a serious issue and don’t harm your TV. If the line is minor and doesn’t affect your viewing experience, you can continue using the TV normally. However, if the line becomes distracting and software settings don’t help, seeking a hardware repair may be the best option.
