I purchased a new Sansung. Within 6 months a black bar showed up on the screen. Fortunately the TV was under warranty. They replaced the power supply. The tech said it was probably caused by a power spike and suggested we use a Backup Power Supply, like the type you use for a computer. We bought one large enough for our TV and so far, it has been about 6 years without any problem. Obviously I can't say for sure this is the problem with your TV.