How Sega optical switches behave
A Sega opto acts like an ordinary normally open switch: breaking the beam closes the switch. The emitters are very bright visible red LEDs, so you can see whether one is lit, and they are little affected by room light. Williams optos, by contrast, are normally closed and infrared.
Systems
Related tips
- Cleaning optical switches
- How the Sega opto receiver works
- Specification for replacement Sega opto LEDs
- An opto shows closed all the time
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)