Missing lamp fuse changes the flash count

The last two power-on tests need the lamp phase signals from the power supply. On an 8-flash game such as Eight Ball Champ, pulling FU5 stops it at 6 flashes and pulling FU4 stops it at 7, so a short flash count can be a blown lamp fuse rather than a bad CPU board.

Systems

• Bally 6803

Games

• Beat the Clock
• Eight Ball Champ
• Lady Luck

Related tips

• How to read the flashes on pre-1988 6803 games
• CPU LED stops just short of the full count
• Expected CPU LED flashes by game
• Nine-flash LED code meanings
• Game boots but will not take credits or start
• Nonsense adjustment values after a battery failure
• Factory CPU jumpers by game
• CPU never starts: check the reset line at U1 pin 6

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