Hmmm, door closed switch, on a quick inspection, perhaps not present....oooh...![]()
Thanks @Jay Walker some great info there, very much appreciated. Some food for thought there. An expensive check under the hood the other nightIt probably went missing with the machines' original door, which would've had a flange holding it, in the top left corner of the frame. I see now that a 'Mars' door is fitted, but the factory fitted Coin Controls door didn't have that provided either. Williams reverted to using the separate holding bracket introduced with the 'Memory Protect' Interlock for Lev. 6 games onwards, in 1979. At least this isn't a Dr. Who, that would object loudly to not seeing the door closed.
Your picture of the Interface circuit board shows the additional jumper wire at W2, also required for an electronic acceptor. The serial number label doesn't have an upper-case 'I' in front of the individual number, so it may have been a domestic spec game.
The door shown by PH is what Williams called a 'DBV' (Dollar Bill Validator) door. The two inset panels can be removed to fit a note acceptor. A Dutch-spec Indy that I converted had one. I've not seen one fitted to anything earlier than a Fish Tales, and it may not have been the factory fitment in any case. A u.s. spec Getaway would probably have had a 2-slot version of the door on your Black Knight 2000, as seen in Ant-H's thread about doors.
Another difference is the mounting for the door switch(es), low down on the left side, with that flange on the door to push it/them closed. I think that placement began with the final examples of Dracula, and seems to have been done with the intention of having two switches, the extra one cutting off the 50 and 20V power rails with the door open. You'd need a switch bracket, placing the switch pointing sideways, to meet the flange on the door.