User:Scott Hively/pinball/black knight/bk electronics
First thing to note is this machine was manufactured in 1981. With age, electrolytic capacitors dry out, plastic connector housings become brittle due to heat / UV / age and electrical contacts oxidize.
And while Williams was innovative in pinball game design, their electrical designs are a bit suspect in a few areas.
This is the original power supply.
Notice the darkened connectors. If Williams needed more current than a connector could handle, they would use multiple pins. This works great for a while until one of the pins has a bad connection, then the others heat up and they begin to fail. Vicious cycle.
The fuse holder in the lower-right corner was badly corroded. The fuse holder would make bad contact, get hot, and de-solder itself from the board. I installed an off-board fuse holder. That's the grey wire you see coming off the board.