How Bally controlled lamps are powered and switched
The rectifier board feeds controlled-lamp power via its fuse F1. Before Xenon (transformer in the backbox) about 7 V AC goes through a 10 A fuse and an 8 A bridge to give about 6 V DC; Xenon and later use a larger bridge and a 20 A F1. A bare bus wire under the playfield carries this to every controlled lamp, and the lamp driver board turns each lamp on by grounding its own wire through an SCR (page 25).
Systems
Related tips
- LEDs flicker in controlled lamps on Bally and Stern SCR lamp boards
- None of the controlled lamps light
- One controlled lamp does not light
- A controlled lamp that is always on means a shorted SCR
- No feature lamp voltage at TP1 (-18 board)
- Many controlled lamps dead in a pattern
- AS-2518-14 vs AS-2518-23 lamp driver boards
- Test lamp SCRs with the power off
Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part Three, Clay Harrell (pinrepair.com)