Just reporting back in.
I replaced the power supply board on the Samsung 51" F8500, and it works like a charm. Easy do it yourself project.
I know it's been 2 months since I posted about fixing the unit, but summer is my busy season. Once I got around to it last week, took little time to remove back and board, ship, recieve and install > reinstall back panel.
Ive been using a Panasonic 50" ST60 in it's place. The Samsung is much better during the day and the Panasonic is noticeably better during night. But they are both great units. (Wish I had the 55" ST60)
$75 shipped, for the board. I got one off eBay from a guy in Haymarket, Virginia. Oleg was his name. Fast turnaround.
Epson 8350 / Panasonic AX-200u / Optoma Graywolf 92" / Draper Luma 92"
Samsung 51F8500 / Panasonic P50ST60 / Vizio P502ui-B1E / Sony 50W700B
Sony S790 / Panasonic BDT-220 / Roku 2 XS & Roku 2
Sony NT5 / Samsung F550 / Speakercraft CS3 / Yamaha YAS-105