Dungeons & Dragons and Blackwater 100 use trough optos

These two games use infrared opto boards in the ball trough instead of switches, and the optos are often flaky. The game will not start unless it counts every ball, so trough optos matter.

Systems

• Bally 6803

Games

• Blackwater 100
• Dungeons & Dragons

Related tips

• Get at the trough opto boards for testing
• Trough opto numbering is backwards
• "Ball missing" with all balls in the trough
• Stop trough optos from breaking with vibration
• Test trough emitters and receivers
• Fitting new trough optos on D&D and Blackwater 100
• NTE replacement emitters fit the opposite way round
• Blackwater 100 has its transformer in the cabinet

Source: Repairing Bally 6803 Pinball Games from 1985 to 1989, Clay Harrell (pinrepair.com)