A pair of flashlamps on one driver stays dark.
Two flashlamps out together
Cause: Flashlamps that share a driver are wired two in series so the 28 V supply suits the bulbs; when one bulb burns out the other goes dark too.
Checks
- Check both bulbs in the pair.
Fix
- Replace the burnt bulb.
Systems
Related tips
- Flashlamps never flash
- Check for power at a coil or flashlamp
- Check the coil diode after replacing a driver
- Fire a coil or flashlamp by grounding it
- Check the wire from the coil to its driver transistor
- Solenoid driver test at 2J9 and 2J11 with Leon's code
- Coil overheated: check its resistance
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)