OUR 40" SAMSUNG LCD TV IS THREE YEARS OLD AND NOW TAKES ABOUT 15 MINUTES TO SWITCH ON EITHER FROM STANDBY OR FROM THE MAINS.

Capactors are failing will not turn on at all soon and the light will flash
replace capactors on mains power board easy to do if got soildering iron look for raised tops on capactors ( they look like little battries with line down and numbers on (e.g 20000mf 25v) there is 3-4 that will need changing close together
replace with some value and make sure the line is on same side as ones that you take out TAKE PICTURE FIRST and replace one at once