It depends on what you mean by "power supply", and what kind of TV. An older "CRT" type TV has a Cathode Ray Tube in it (hence the name) and it requires an extremely high voltage power supply, built in where you're not supposed to get into it. It does have a fuse, and if the fuse is blown, only replacing the fuse will get your TV to work again IF you know WHY the fuse got blown.
If you don't, then your new fuse will blow too. A TV repairman is what you need, but those are hard to find these days. Good luck.