Why does my TV have sound but no picture? - RCA Televison & Video

Hello
Flat-panel LCD TVs have a lifespan newly approaching 100,000 hours on average. The lifespan of an LCD TV is generally longer than that of similar-sized plasma televisions. Some manufacturers even claim that their LCDs can last upwards of 100,000 hours when used continuously under controlled conditions (e.g., in a room with "standard" lighting conditions and 77° temperatures throughout). Just how realistic such claims are is debatable. After all, whose living room has no windows and remains at a perfectly comfortable 77 degrees year-round?
In any case, the pictures on fluorescent backlit LCD TVs will show some "wear" because they are generated by powerful lamps, which, like any lighting appliance, will dim over time and with use. The picture you see will dim ever so slightly as the backlighting bulbs dim. One other consideration is that CFL fluorescent backlighting will change colors over time. This will change the white balance on your TV and cause color calibrations to be thrown off.
Therefore, the most important thing to consider when it comes to the lifespan of your LCD TV is the actual lifespan of the light source in your LCD. LCD TVs last as long as their lightsources do. So, the lightsource in your LCD TV is the critical component of your LCD display unit. Newly introduced LED backlit LCD TVs will have the best long term performance. LED backlighting is superior in that the white balance of the TV will not be affected by changing bulb color over time. It's a more consistent bulb technology and will also maintain its brightness longer.
The edge lit version of LED TVs will use far less energy while local dimming LED backlighting will be more accurate and present a better picture while using more power. We believe that local dimming LED backlighting will be slightly less stable from a life span standpoint.
To ensure the integrity of your lightsource for the duration of your LCD display's lifespan, you will definitely want to adjust the CONTRAST setting of your LCD TV. Too high of a CONTRAST level will prematurely age your lightsource because it will have to work harder to maintain such light intensities. Your best bet is to keep your CONTRAST set appropriately for the conditions under which your view your LCD display. Brighter ambient light levels require slightly higher CONTRAST levels, while lower ambient light levels demand less CONTRAST.
Hope this helps

Please try this:
First, look at the screen in darkened room to see if you can see any slight glow from the screen, if it does, then the problem can be the T-CON (not getting the 12vdc) or the main logic board not feeding the signals to the T-CON board.
if not, next place to check will be the power supply module, make sure it has 24vdc which is required by the backlight inverter to work, the reason for not having 24vdc can be from bad DC filter caps (leaking/bulging top, high ESR) or short circuits in the inverter board which will cause the 24vdc supply to go into shutdown mode, so you may have to disconnect the power cable that feed the inverter board to see if the 24vdc will work without the inverter board hookup, you will need to apply about 3~4 amp of load to the 24vdc to make sure it can handle that. There are fuses on the backlight inverter boards also. So there is some troubleshooting you will have to do to find out the causes of the problem you are having.

If you are going to DIY and have proper tools, electronics knowledge, and know safety precaution then please read on:

Basic LCD monitor and TV troubleshooting guide:
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r7406380-tv_training_manuals
Failed TV and Monitors pictures: http://s807.photobucket.com/albums/yy352/budm
Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague
Parts: www.shopjimmy.com
Parts: http://interliquidparts.com/

Capacitors kit: http://lcdalternatives.auctivacommerce.com/Default.aspx he can make you a set of caps.
Or www.digikey.com, just make sure to use caps with low ESR, 105c, high ripple current and long life rating such as PANASONIC FM or FC series.