Some WPC-95 optos can fail even when they test good

Older WPC optos use plain photo receivers, but some WPC-95 games use receivers with a built-in transistor stage that can fail while the light sensing part is fine. If the transmitter shows light on a sensor card and everything else checks out, replacing the opto is the only fix. This fault is rare and hard to pin down.

Systems

• WPC-95

Related tips

• How WPC opto switches work and which half fails
• Opto styles used in WPC games
• Where WPC games use opto switches
• WPC-95 five-leg Schmitt trigger U optos
• Replacement five-leg U slot opto (WPC-95)
• Opto switches dead or intermittent: check the 12 volt supplies
• 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)