The CPU LED stops one or two flashes short (6 or 7 on an 8-flash game, 7 or 8 on a 9-flash game) and the game will not run.

CPU LED stops just short of the full count

Cause: The lamp phase test failed: usually a blown FU4 or FU5 on the power supply, otherwise U12 (4584), U11 (4011), U8 (6821) or the zero-cross circuit.

Checks

• Check FU4 and FU5 and measure 11 VAC at TP6 and TP7 on the power supply.
• Check that the 2x12 VAC signal reaches the CPU board (J1 pins 3 and 4).
• Look for about 2 V at U12 pins 2 and 6.

Fix

• Replace the blown fuse; if the phases are present, replace U12, then U11 or U8.

Systems

• Bally 6803

Related tips

• Expected CPU LED flashes by game
• Eight-flash LED code meanings
• Missing lamp fuse changes the flash count
• CPU never starts: check the reset line at U1 pin 6
• How to read the flashes on pre-1988 6803 games
• How to read the flashes on the last four 6803 games
• Game boots but will not take credits or start
• Random resets and lock-ups from the +5 V filter cap

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