Hi, this could be a problem with the power supply in the tv, it is common to samsungs and repair kits are available quite cheaply if you have good soldering skills.
Usually this is caused by capacitors that have dried up and split, you can normally tell as the capacitors are bulging on the pcb, you can get them in a kit as I said eBay sometimes do them or you can buy them indivually from a good electronics components supplier, make sure you get the correct values for each!! marked on the side of the capacitors in xx/v V, xxx/x uF and 105oC.
The picture below shows the type of theing that happens, the brown ones are bulging/split on the top whereas the black one is fine.
High Voltages can exist in these sets, never attempt anything while plugged in and
if in doubt do not attempt it yourself and seek the advice of a qualified TV Technician.