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TV has sound but no picture
If your TV has sound but no picture, the problem is generally a backlight issue with a straightforward solution. Schedule TV repair service to either replace your TV’s backlight lamp, ballast or the inverter, depending on whether it is DLP or LCD.
DLP (Digital Light Processing) TVs are rear-projecting and create pictures by using a complex system of microscopic mirrors (the digital micromirror device or DMD) to reflect or deflect light onto the screen that we face.
DLPs produce realistic pictures composed of colors that are brighter and blacks that are deeper.
If your DLP TV has sound but no picture, there are 3 likely points of failure:
- The backlight lamp
- The ballast
- The color wheel
1. Backlight lamp
The backlight lamp is responsible for sending a white light through color wheels to produce the amazing images we see. No lamp, no images—but sound is unaffected. The average life of a DLP lamp ranges from about 4,000 to 8,000 hours; that’s at least 2 years of use. If your TV is a few years old, it may be time for lamp replacement. This is a simple DIY task. See our step-by-step guide to DLP lamp replacement.
Tip: For fair warning that your DLP TV backlight lamp’s days are numbered, look for an LED indicator light above the lamp icon on your TV.
The ballast provides the lamp with a steady electrical current that is necessary for starting it up and keeping it powered. It can be tricky to determine whether your issue is with the lamp or ballast without professional help, but if you already or recently replaced the lamp and you are confident that it is good, you likely have a faulty TV backlight ballast. Schedule TV service to be sure. You may need to have it replaced.
3. Color wheel
When operating properly, the color wheel spins at high speed and makes a sound that is often mistaken for a fan. If the wheel machinery starts to wear out or malfunction, that sound can become much louder, or even devolve into a maddening grinding or squeaking. The picture may be lost or partially lost or take on a rainbow effect.
A malfunctioning color wheel may also start and then shut itself off after a few minutes, causing image problems only intermittently.
Replacing a color wheel is a delicate procedure, so leave the diagnosis and repair to a professional.
Note: Newer DLP technology using lasers is now available in some TV sets and eliminates the need for a backlight lamp and color wheel.
If you have an LCD (liquid-crystal display), you may suffer from a TV backlight lamp or backlight inverter failure.
1. Backlight lamp failure
A good way to tell is if you can just barely see images moving on the screen when you angle a flashlight at it in a darkened room. A failed TV backlight cannot light up the liquid crystals forming those images.
2. Backlight inverter failure
If the problem lies with the inverter, your backlight bulb may be fine, but it won’t receive power from the inverter and you have the same resulting problem—TV has sound but no picture.
You will need to reach out to a repair specialist to have the TV backlight or backlight inverter replaced before you can enjoy picture with your TV sound once again.
You should know, however, that backlights for most LCDs are generally unavailable. You may have to buy a new TV if that is the case for you.
Tip: Fluorescent bulbs will dim over time. So the next time you notice a dimming picture, take it as an indication that your LCD’s backlight is just about ready to quit.
Did you know? Overheating is a top cause for shortened lamp life. Keep your TV backlight system well ventilated and avoid overuse of the power button. Turning the TV on and off repeatedly without allowing it time to cool down in between overheats it.
✓ Reviewed and approved by Repair.com expert Greg Roth, general manager, Roth’s.