If you read the Cnet Samsung forums many are reporting one time free fixes for the bad cap plague.
PLEASE UNPLUG THIS SET TO AVOID any further damage.
The TV was about 1.5 years old, started screen would blank after 20 minutes or so, sometimes not until several hours of viewing. Only way to regain picture was to power off and back on and then usually it would be okay for another twenty min or more. Sometimes it would take several power cycles to get picture to stay on (you would see the input mode flash briefly in the upper left of screen). If the room was dark you could see that the fluorescent backlight was shutting off. Audio was always okay and acted same for any input. I had ordered a service manual and when I received it, the TV mysteriously started working fine and had for a couple months. Now it won't even power on normally. Just get audio and sometimes a brief flash of the picture and then black.