No picture - audio ok. Power cycled (unplugged for 30 seconds) but didn't resolve. Picture comes on when powered on, disappears after a second.

The first things to try are of course the simplest. If you have a picture on your TV but no sound, the problem might be as simple as having the “Mute” button the remote having been accidentally pressed. Grab your remote and unmute the TV by pressing the “Mute” button again.
Next, check what the input setting is on your Samsung TV by hitting “Source” on the remote and cycling through the available inputs. If your Samsung TV’s source is set to a component that you don’t have set up, then there won’t be any audio data coming in to be played.
Do you ever use a headset on your TV? Gamers, in particular, might be using a wired set of headphones plugged into an audio out jack, and if the headphones are plugged in, then any audio is being routed to that equipment, and you might not hear the sound playing if you aren’t wearing the headset. Assuming you never use a headset on your TV, check the headset port for any debris. Your TV may pick up something in the port which won’t allow the audio to route properly.
Finally if this does not work,you can try the old school way...unplug the your TV for about an minute.

You may have either failing 24vdc power supply or the backlight inverter board.
If you are going to DIY and have proper tools, electronics knowledge, and know safety precaution then please read on:

Please see my basic troubleshooting guide here:
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide

http://s807.photobucket.com/home/budm/allalbums

http://en.wikipedia.org/wiki/Capacitor_plague

Parts: www.shopjimmy.com
Capacitors kit: http://lcdalternatives.auctivacommerce.com/Default.aspx

This time Ur LCD inverter board is dead,must replaced that board to get picture back.The board is a long board.

Sounds like the digital board needs replaced.

http://www.avsforum.com/avs-vb/showthread.php?t=928945&page=19 <try this and good luck! let me know if it helps...

turn tv on picture comes up 2to3 seconds later tv blacks out then stand by red light flashes 4 times in a row repeatedly..can not turn on or off when stand by light starts flashing but before tv blacks out you can turn tv on and off repeatedly and picture and sound work.You have to unplug power cord for 30 seconds after stand by light comes on to get tv to turn on.

I had the same problem, green screen, no picture, audio OK. DVD player had a picture. Our other TVs were OK. Cable provider had me unplug my cable box for 30 seconds and plug it back in and now it works! I found this out by an online chat with my cable provider.

I've had the same issue although I don't unplug everything. I turn it off and then unplug it from the wall for 10 seconds then plug it back in. Seems ok after that. Has happened 4 or 5 times over the 10 years I've owned it.

AKB circuit (automatic kine bias), the timer/standby indicator blinks for about 30 seconds then goes to the self-diagnosis function. Something is wrong with the video. Check video out, Q705, 732, 761 and other components on the Cboard, also check Q218, 219, 220 on the A board. In addition, unit could be in IK blanking.

blown pico fuses and bad stk packs