A whole switch row does not work, with the playfield ruled out.

One switch row dead: parts to check in order

Cause: A failed resistor network (RA16, RB5 or RB6), then the 4011 at 5J or 6J, then the PIA at 8H.

Checks

• Test RA16 (560 ohm x 8 bussed).
• Test RB5 and RB6: each resistor should read 1k.

Fix

• Replace any bad network.
• Then replace the 4011 that serves the dead row (5J for rows 1 to 4, 6J for rows 5 to 8).
• Replace the 6821 at 8H last.

Systems

• Data East CPU Version 1/2
• Data East CPU Version 3
• Data East/Sega CPU Version 3b

Related tips

• Whole switch column dead after working under the playfield
• One switch column dead: parts to check in order
• Switch matrix dead after an under-playfield adjustment with power on
• Fixing a dead switch row on the CPU board
• System 11 switch matrix: connectors and chips
• Switch row (return) circuit on the CPU board
• Switch column (drive) circuit on the CPU board
• One PIA output does not toggle under the test EPROM

Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)