I have a Samsung TV about 2-1/2 years and the main PC board needs to be replaced. Is that normal? That's all it's used for watching television. The picture started to get dark in the top right corner a few months ago and then seemed to get better until yesterday when I turned on the tv and saw a flash and there was no picture, just sound. I had an old Sharp CRT for 44 years that worked like a dream but the picture had turned cloudy so it was time for a new one.
Samsung being the top dog should be the better of the bunch, but in general the days of Sony Trinitrons lasting you 30 years is history. These days, cheap, fast (to market) is the norm, nobody bother to run through lengthy quality control.