Opto receiver and transmitter voltages
With the beam unblocked the receiver shows about 1 to 1.5 V DC across its leads (no switch closure). Blocked, it shows about 11 V DC. The transmitter LED should always have 1 to 3 V across it, dropped through a resistor from the 12 V supply.
Systems
Related tips
- Millionaire was the first Williams game with opto switches
- Fitting replacement optos the right way round
- Opto switches dead all at once
- System 11B opto board fails with good optos
Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Three, Clay Harrell