4-player Williams EM owners... I may have found a disturbance in the Pinball Force.
Maybe. Let me explain. This one comes from a '72 Fan-Tas-Tic.
The section at the upper left is a switch in the tilt relay. The score reels (and free credit for high score) get their power through this switch. It is normally closed (i.e. when game is not tilted).
Our culprit, pictured up close. Yellow common on one side, white-orange on the other.
The question to ponder: Why cut power to the score reels when the game is tilted? Tilting the game already cuts power to the score relays, so why worry about the reels?
The action to ponder: If this switch for whatever reason fails to stay closed (game not tilted), the reels won't move. However, the score relays can still be energized! And thus, the nightmare situation... cooked chimes, match coils, and relay coils. Possibly several all at once.
For safety's sake, why not eliminate this switch altogether? This will guarantee power to the reels at all times.
I don't know why Williams did this. Correct me if I'm missing something, but I don't see any benefit to cutting power to the reels during a tilt. The score relays get cut anyway, so what is the point? Seems better to eliminate this potential source of failure (and fire) and permanently jump it closed... just in case.
I looked at Space Mission/Odyssey and it has the same circuit design. Looks like many other Williams'ses share it as well.
Anyone see any reason why this switch should be preserved?