Often on these PS boards...if the main run voltages fall to 0 (the VS and VA lines) the power WILL just "click on and off continuously". No VS or VA supply means that one of the SMPS ckts is not working--either due to a bad load on the clod side--or not running on the primary side.
Have you checked to see if the FET'S that drive that upper transformer are not shorted...and a fuse or resistor feeding them open? If not...perhaps a diode on the secondary of those supplies is shorted.
often...there are "kits" on ebay or shop jimmy--with the parts that fail on these PS baords... they work good for someone who is not used to troubleshooting down to the "nitty gritty".. FInd the boars and order by that... looks like BN44-00274A
THIS..likely will fix your PS board::
http://www.ebay.com/itm/Samsung-BN44...4AAOSw-7RVHtP-