My Sylvania 6626LCT has blacked out, no picture, yet has sound.

Most likely your set is experiencing a panel backlighting problem or powersupply problem.

Simple checks:

When you first turn on your set, look closely at the panel. If it lights up momentarally then darkens instantly, you need a new panel. If it does not light up for even a fraction of a second, then it's most likely you need a new powersupply board. There have been cases of which a new panel and power supply boards both needs replacement, however this is rare.

Goto this website for model search and parts availability. http://www.encompassparts.com/

If they don't list your model number, gotto CONTACT INFO and try calling numbers they have listed. They are good about finding parts you need, even if your not a qualified technician.

One good thing about these Flat panel LCD, is that it doesn't take a rocket sientist to replace panels or boards. Some models however maybe a bit difficult on doing full panel replacements, but small models as yours is a peice of cake. Just remember where all framework and screws belong so you can get your set back together without any problems.