I've got some issues with Black Knight.
It boots up into attract mode and I can add credits but it won't start a game. Nothing happens when I press the diagnostic switches.
There is continuity from the blue and green wires on the coin door diagnostic switches to the connector in the head.
With 1J4 disconnected, I have tried momentarily grounding 1J4 Pin 3 to 1J4 Pin 2 which gets the machine into the display test, I can then cycle through the display numbers by repeating this. I also have tried momentarily connecting 1J4 Pin 3 to 1J4 Pin 4 but nothing happens. Does this mean there is a cold solder joint at 1J4 pin 4?
Are there any other tests I could try to narrow it down?