Techno Stuff
How They Work - Search Disc

The search disk is usually the big contact plate in the head at the end of the control unit shaft. On some games, especially six-card machines, there may be two search discs. The search wipers are clutch driven, so you can stop them from turning by holding them in place. You'll want to insulate yourself - or better yet, get a neighbor to hold the thing - at least you won't get zapped.

The function of the search disc is twofold:

  • operate the search relays to step through possible winning combinations of balls in the playfield holes
  • in some machines, adjust payout level for bonus wins (e.g. 3-in-line on a supercard scores as 4-in-line
search disc
surf club
search disc diagram - without contact identification

On older games, the actual wiring of the search disc may not be shown. Usually this isn't a problem, as there was no real incentive to messing with the wiring on the contact plate. If, however, you happen to have a machine that someone has modified to remove features, then it is possible that you need more info than this picture provides. Fortunately, even in those cases, you can eventually figure out what goes where.

The search wipers rotate clockwise, and in this game, the search wipers are always turning while the motors are on. Later games have an R-button on the foot rail to release this wiper unit when it is okay to look for winners. Besides preventing replay scoring when it wasn't wanted, the R-Button also significantly reduced wear on the wiper finger contacts.

The circle in the center of the wipers represents the slip rings. It is good to check that you have continuity from the slip ring wiper to the associated search wiper finger. In this case, there are five slip ring wipers, and they connect to search wipers on rows 5-9.