your problem is most likely caused by four capacitors in the power supply. Usual values 1000uf 25v. It is common and would require the power supply to be replaced or the capacitors themselves to be replaced.
The tops of the four failed capacitors bulge when they have failed. Always replace them with the 105c high temperature type. Samsung do supply power supplies but they are sometimes out of stock for some models. Sometimes just easier to replace the caps and be done with it. Usual warning of "dont do this if you dont have a clue" applies.
I would advise not to leave this too long or use it when this fault is occurring as if left long enough it can damage the main board as well
I am dead
December 2009