Installed the new SU board and everything fired up just fine. The TV Worked for a day and then turned off with 7 blinking lights again. Maybe it is the two Caps people are talking about? They could not be regulating the voltage properly and damaging parts. I felt I was so close...
I have a TH-50PX75U with the exact same symptoms as your set. With the help of this board I was able to diagnose the problem to the SU board. Very hard to find this part for this model, but someone in Canada had disassembled one of these and was selling the parts on eBay. I bought the SU and SD cards (sold as a pair) and they are on their way.
I thought I had this nailed but you have now made me very nervous. I'll let you know how it goes.