NTE replacement emitters fit the opposite way round

The trough uses metal-can TO-18 optos: emitters MLED930 (NTE3028) and detectors MRD370 (NTE3036). The NTE emitters are polarized opposite to the originals, so install them with the tab turned away from the position on the silkscreen.

Systems

• Bally 6803

Games

• Blackwater 100
• Dungeons & Dragons

Related tips

• Test trough emitters and receivers
• Stop trough optos from breaking with vibration
• Dungeons & Dragons and Blackwater 100 use trough optos
• Get at the trough opto boards for testing
• "Ball missing" with all balls in the trough
• Fitting new trough optos on D&D and Blackwater 100
• Build a replacement keypad

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