Old and new WPC ball trough designs

Up to 1993 WPC troughs used mechanical switches and two coils: an outhole kicker and a trough-to-shooter kicker. From Indiana Jones (1993) on, balls roll into the trough by gravity (no outhole coil) and are sensed by opto boards on each side, so one trough design holds one to six balls, most games using four to six.

Systems

• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• Opto ball troughs from Indiana Jones on
• Full ball trough opto test in switch edge test
• Bench testing a trough transmitter board
• Outhole kicker struggles when two or three balls drain together
• Replacing trough transmitter and receiver optos
• Balls hang in the trough and none is served: divots in the trough floor
• "Pinball Missing" message
• "Pinball Missing" message

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Three, Clay Harrell (pinrepair.com)