I've yet to see any TV tech estimate except on the very high side without seeing the set. Some folk want a guess and that I can do but you accept it's just a guess. I'd try a new power supply board first but if the TV had other signs such as power cycling then coming on, then the cycling could fry other boards. Figure a power and a main board plus the shop charges.
Bob
Bought this tv in 2011 no warranty - paid $1499 and sure did Not expect a Samsung TV to break so soon. The tv won't stay on or off. This seems to be a common problem. I called Samsung and they offered a phone number to their service number in Carrollton, TX and a transaction number. Waiting for service center to answer my voice mail. Basically I'm on my own to pay for this. I gave up my Panasonic Flat screen that had no problems for this. Oh dang! I hope this doesn't break the bank right after Christmas. So disappointed.
Anyone out there who can give me an idea how much this repair will cost?
I asked Samsung if they offered any repair discounts for this very common problem but the answer was ill gone you a transaction number to give the I service center. So the answer was basically no. Not sure how the Samsung trans # will help.

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