I consider you must check the capacitors. Call customer service in your TV book that came with the TV. They will find you a repair shop near you to get the part you need to replace. I recommend you www.tvrepairjacksonvillefl.com I hope this helps, I had similar trouble with mine, had to replace the part. It eventually went out again so I just tossed the TV and bought another. I got 5 more years of use out of the first replacement part.
evan
July 2012