Opto styles used in WPC games

WPC games use one-piece U-shaped slot optos (Fliptronics flipper buttons, the Twilight Zone clock and similar) and two-piece stand-up optos where a green-board transmitter faces a blue-board receiver. The transmitter LED is the larger one and sticks out further from its case. The same single infrared LED replaces stand-up transmitters and the LEDs on trough opto boards.

Systems

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

Related tips

• Where WPC games use opto switches
• Some WPC-95 optos can fail even when they test good
• Original-style U optos are now scarce
• WPC-95 five-leg Schmitt trigger U optos
• Replacement five-leg U slot opto (WPC-95)
• Testing an opto receiver
• Opto parts to keep on hand
• Cleaning dusty optos

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