Any ideas what an NT407F is?
My best guess is it's a MOSFET, TO-220 insulated package, probably 400 to
800V, a few amperes Id, and enhancement mode. The only thing I can find on the internet is a specious link between the acronym "MOSFET" and the part number, everything else I gathered from the board. Beyond this, I have no clue...
Although, the drive transformer looks to have thick secondary wire, they may be BJT's after all.
Tim