Also:


1960s & 1970s Gottlieb Start-Up Sequence.
Games with score reels.
Inserting a coin or pressing the coin door start button (Gottlieb calls this the "replay" button) activates the "S" (start) relay. The start relay will lock on from its own switch and a score motor switch.
The "S" relay will energize the main hold relay to illuminate the game (if this is the first game after power-on).
The "S" relay will start the score motor running.
The "S" relay and the score motor increment the total play meter.
The "SB" relay (the secondary start relay) is activated through the score motor. The "SB" relay energizes the reset relays ("Z1" and "Z2"). If a single or two player game, there may be only a "Z" relay.
The "Z2" relay will reset the player 3 and 4 score reels to zero through the score relays (4 player games only). The "Z1" or "Z" relay will reset the player 1 (and player 2 if present) score reels to zero through the score relays.
The "SB" relay resets the player unit through the score motor.
The "U" relay resets the reset bank (or Ax, Bx, relays on 1975 and later multi-player games and Ax on single players) through the score motor. It also resets the bonus unit or drop target banks (if the game has these).
On multi-player games, inserting more coins or pressing the coin door start button activates the "PBx" relay, through the score motor. The "x" represents the player number (from two to four).
If the ball is in the outhole, the "O" relay activates. The "O" relay, through the score motor and a switch on relay "XB", will kick the ball to the shooter lane. Note: the "O" relay will not activate unless the bonus unit (if the game has one) is reset to zero (there is a bonus unit zero position switch).
When the ball re-enters the outhole after game play, the "P" relay kicks the ball back to the shooter lane. Switches on the "XB", "ZB", "P" relays and some score motor switches advances the player unit (if present) and player relays ("PBx").