Lamp tests: phases and single lamps

Test 90 flashes every matrix lamp together, phase A first and then phase B, which separates a dead phase from a dead SCR. Newer games add a single-lamp test that also shows the SCR number and connector for each lamp; A steps forward, B back and C cycles.

Systems

• Bally 6803

Related tips

• How the CPU keeps lamp phases in step
• Lamp driver SCRs on the CPU board
• Single lamp out, dim or flickering
• How 6803 feature lamps share SCR drivers
• The Solid State Relay board switches the backbox lamp
• Swap a hot incandescent backbox lamp for fluorescent
• None of the CPU-controlled lamps light
• Replacing a bad diode on a Bally 6803 wedge lamp socket

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