Fitting a replacement U slot opto the right way round

Steps

• Note which leg of the neighbouring original opto is the transmitter before removing the old part.
• Line up the dot or notch on the new opto with the dot printed on the board. The old Radio Shack 276-142 U opto is the exception: its dot goes opposite the board dot.
• If the new opto has no dot or notch, put its legs marked S and + nearest the board dot.
• Power up and use an infrared card to find the transmitter leg; it should be in the same position as on the neighbouring original optos.
• A U opto fitted backwards usually isn't damaged, but the switch won't work.

Systems

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

Related tips

• Replacement five-leg U slot opto (WPC-95)
• Mounting a replacement opto receiver
• Replacement opto transmitter and receiver pinouts
• Replacement opto receiver dead or weak: try it with the notch the other way
• Bookcase opto still dead after a new receiver: the replacement part was bad
• Testing an opto receiver
• Opto parts to keep on hand
• Opto styles used in WPC games

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