How to Diagnose & Repair Desktop LCD Backlight Problems

By Ty Arthur

Diagnose & Repair Desktop LCD Backlight Problems
i Samsung

The liquid crystal display (LCD) monitor that connects to your desktop computer is powered by an inverter board and a cold cathode backlight bulb that shines a light through a sheet of plastic to display images on the screen. If your LCD monitor is no longer displaying images the problem is most likely caused by the backlight bulb burning out. You can repair the monitor by manually removing its case and replacing the burned-out bulb.

Power on your computer and wait until there should be an image displaying on your LCD monitor. Look directly into the monitor from a distance of about 1 inch way. Cup your hands around your face to block out the light in the room and get a clearer view of the LCD screen. Check to see if there is a faint light visible in the screen, which will indicate that the cold cathode backlight has gone out, or no image at all, which will indicate a different problem.

Check the manual that came with your desktop LCD monitor or navigate to the manufacturer's website and find the model of cold cathode bulb that the monitor uses as a backlight. Purchase a corresponding replacement bulb.

Power off your computer and then remove the monitor cable from the port on the back of the computer case. Disconnect the monitor stand from the monitor either by pulling out the plastic latches or by removing the screws holding it to the monitor's casing.

Lay the monitor face down onto a stable work surface such as a desk or table. Take out the screws along the edges of the monitor's casing and set them aside. Lift the back side of the monitor case off of the monitor and set it aside. Check to see if your model of LCD monitor has the backlight directly exposed on the lower end of the monitor or if it is hidden behind another plastic or metal piece.

Remove the screws holding the plastic or metal piece over the bulb if there is one present and set the piece aside. Check to see if your model of monitor keeps the bulb in a plastic casing or if it is soldered directly to the metal. Use a soldering tool to remove the solder or instead use a rotary cutting tool to cut into the clear plastic casing around the bulb if it is inside a case.

Slide the new bulb into the open spot on the monitor and either solder it in place or use a piece of tape to cover over the opening you made on the plastic casing with the rotary cutting tool. Place the metal or plastic cover back on if there was one and reattach the screws. Set the casing back onto the monitor and place the screws back in.

Put the stand back on the monitor and then reconnect it to your desktop computer. Power the computer on and wait for an image to appear on the screen to make sure the backlight bulb was installed correctly.