Opto wavelengths: 880 nm and 940 nm

Williams used 880 nm infrared optos almost everywhere, but that wavelength is now hard to buy and most current parts are 940 nm. 940 nm parts reject sunlight and lamp light better and reach further. Avoid pairing a 940 nm transmitter with an old 880 nm receiver, which can give trouble; replace both halves together.

Systems

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

Related tips

• 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
• Checking an under-playfield opto board for bad LM339s

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