What causes horizontal lines on a TV screen

It is always challenging to pinpoint the cause of horizontal lines on a TV screen. The cause might be the motherboard, loose panel and control board cables, or a software glitch.

If it is a software problem, the fix may include resetting your TV or updating the firmware. But if you have an issue with the hardware, this will require further diagnosing, including enlisting the service of a professional.

Here is a look at the possible causes of horizontal lines on a TV screen and how to fix them.

1. Memory leaks

Your Smart TV usually requests or allocates memory and then forgets to free it when it is no longer needed, resulting in a memory leak.

The leak can cause a program to consume more memory, leading to performance issues and crashes.

While there is no direct link between memory leaks and horizontal lines on a TV screen, it may be a possible cause. Therefore, try fixing this by restarting your TV.

Unplug your TV from the power supply, wait for 60 seconds, plug it back in, and see if it fixes the problem.

You may also have to update your TV firmware to fix glitches with your device.

2. Loose cables

HDMI ports on an LG TV
Check the HDMI ports on your TV to confirm they aren’t loose.

Loose cables can cause horizontal lines on a TV screen. Cables that connect to your TV, such as a cable box, Blu-Ray player, or gaming console, can become loose.

When this happens, it disrupts the transmission of the signal to the two devices. As a result, horizontal lines can appear on the screen. To fix this issue, try the following:

  • Unplug the cables from the TV and the device it is connected to.
  • Check the connections to make sure they are clean and undamaged.
  • Tightly plug them back in.

Once you power your TV, check if it has corrected the problem.

It is also worth checking your HDMI cables. HDMI cables transmit audio and video signals from a device to a TV.

Though reliable, they can sometimes cause horizontal lines on a TV screen if they are loose, faulty, or incompatible.

Therefore, secure the HDMI cables tightly to the TV and device, clean them if dirty, and check for physical damage to the cables. Also, check the HDMI port to ensure it is not damaged.

3. Interference from other electronic devices

Horizontal lines on a TV screen can also occur if there is interference from other electronic devices.

The problem is common when two devices with different electrical properties are placed close.

Try fixing this by moving the TV away from other electronic devices or turning off nearby devices.

Wireless routers and microwaves are examples of devices that can interfere with your TV by disrupting its signals, especially through electromagnetism.

4. Loose, dirty, or damaged ribbon cable

A sample ribbon cable
A sample ribbon cable

Ribbon cables are thin, flat cables that connect the driver board to the LCD panel of a Smart TV.

They transmit the image signal from the driver board to the LCD panel. Check to determine whether the cables are loose or damaged.

If the ribbon cables are loosely connected to the driver board or the LCD panel, they can cause horizontal lines on a TV screen.

They can become loose because of wear and tear over time, physical damage to the TV, or moving the TV to a new station.

Also, ribbon cables can become damaged because of physical stress or exposure to extreme temperatures. If the cables are damaged, they can cause horizontal lines on the TV screen.

It is worth checking whether the ribbon cables are dirty or corroded. Dirt or corrosion causes a poor connection between the driver board and the LCD panel, resulting in horizontal lines on a TV screen.

You can fix this issue by reseating the cables to ensure they are securely connected.

  • Please turn off the TV
  • Remove the back panel
  • Locate the ribbon cables
  • Gently push them back into place.
  • If the cables are dirty, clean them. But if damaged, replace them.

5. Faulty T-Con board

The T-Con board generates video signals sent to the LCD panel. You can find the board at the top or bottom of the TV panel.

A TV T-Con board
A sample T-Con board for a Samsung TV

A faulty T-Con board is usually associated with horizontal and vertical lines on TV screen. 

However, since the T-Con board controls the timing of the signals to the LCD panel, if it is damaged or faulty, the timing of the signals will be off, resulting in horizontal lines.

A T-Con board can fail because of manufacturing defects, power surges, overheating, physical damage to the TV, wear and tear, poor power quality or supply issues, and incompatible firmware.

The best fix for a faulty T-Con board is to replace it. However, if your TV has bonded the T-Con board with the panel, you cannot replace it. Instead, you will have to buy a new panel.

6. Faulty gate drivers

Gate drivers are electronic components that control the flow of electrical signals to the pixels on a TV screen.

Gate Drivers on an LED TV screen
How gate Drivers attach on an LED TV screen. Image: Facebook/@LCDLEDTVRepair

In other words, they send signals to the pixels to turn on and off. You can find gate drivers on the side of the TV panel.

When gate drivers are faulty, they can cause many issues with your TV. For example, if one driver fails, you will see a thin black horizontal line on your screen. But if several drivers fail, you will see many thin black horizontal lines.

Gate drivers can fail for various reasons, including a manufacturing defect or wear and tear. Also, any physical damage to your TV can cause the gate drivers to malfunction.

A faulty gate driver will not send a signal to the pixels on your TV screen, causing the screen to display incorrectly or the horizontal lines.

Unfortunately, you cannot easily fix gate drivers. Instead, you will have to replace the entire panel.

How much does it cost to fix horizontal lines on a TV?

Fixing horizontal lines on your TV can start from $150. The cost varies significantly depending on the cause of the problem and your TV.

For example, if damaged cables cause horizontal lines, the cost to replace them will be between $70 and $200. If you have a cracked screen that requires replacing, you must pay between $400 and $1,000.   

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