After fitting a CPU board from another game, none of the switches in one column (strobe 5) work.

Switch column 5 dead after swapping in a CPU board

Cause: The board is jumpered for a game that does not use strobe 5 (JW8 in instead of JW9).

Checks

• Compare the board's JW8-JW11 jumpers with the manual or jumper table for this game.

Fix

• Fit JW9 and remove JW8 when the game needs strobe 5. Blackwater 100 for example lists JW2, JW4, JW6, JW9, JW10 in and JW1, JW3, JW5, JW7, JW8, JW11 out.

Systems

• Bally 6803

Related tips

• Flipper switch shorting into the lane change switch
• Switch matrix connector voltages under the test EPROM
• What is on the 6803 CPU board
• CPU board test points
• How the CPU keeps lamp phases in step
• Expected CPU LED flashes by game
• Bench-test a CPU board with the 6803 test EPROM
• Lamp driver SCRs on the CPU board

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