Reusing an original U opto case with new internals

Steps

• Before opening the old opto, note which side is the transmitter.
• Pry the black case apart from the bottom with a small screwdriver.
• Fit the new transmitter into the spots marked A and K and the receiver into the spots marked C and E.
• Snap the case back on with its dot in the correct place. Where no ball can hit it and no stray light falls on it, the case can be left off.

Systems

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

Related tips

• Original-style U optos are now scarce
• Testing an opto receiver
• Opto parts to keep on hand
• Opto styles used in WPC games
• Cleaning dusty optos
• Testing optos in switch edge test
• Checking LM339 comparators on opto boards
• Flipper cabinet opto switch boards

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