A single feature lamp stays dark in the lamp test.
One controlled lamp does not light
Cause: Most often the lamp socket; otherwise the bulb, a broken .100" connector pin, a cracked header joint on the lamp driver board, or the SCR.
Checks
- Run the first self test so all controlled lamps flash.
- Try the bulb in a known-good socket. If it works, refit it and twist it in its socket a few times.
- With a logic probe, compare the pulses on the tip of a working socket with the dead one; matching pulses mean a socket fault (page 26).
- Trace the lamp's wire colour to its lamp driver pin; check the female pin in the housing and the header solder joint.
- Find the SCR for that pin and compare it on diode test with a neighbouring good one.
Fix
- Replace the socket, or solder it so it cannot turn and run the tip wire straight to the socket tip.
- Repin the connector, reflow the header joint (avoid bridges between the close .100" pins), or replace the SCR.
Systems
Related tips
- How Bally controlled lamps are powered and switched
- Controlled lamps flicker or stay out after fitting a replacement lamp driver with LEDs
- A controlled lamp that is always on means a shorted SCR
- A playfield target lamp never turns off
- Some controlled lamps out: cold solder joint on the lamp driver board connector
- LEDs flicker in controlled lamps on Bally and Stern SCR lamp boards
- One controlled lamp dead even after a new SCR: lamp driver board fault
- One drop target lamp won't light after board work: broken wire in the harness
Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part Three, Clay Harrell (pinrepair.com)