System 11 switch matrix: connectors and chips
The matrix is 8 columns by 8 rows (64 switches). Columns leave the CPU board on 1J8 through 2N3904 drivers Q42-Q49, then a 74LS244 at U40, to the 6821 PIA at U38. Rows come in on 1J10 to 4011 chips U30 (rows 1-4) and U39 (rows 5-8), which feed the same PIA; on System 9 these row chips are U51 and U52.
Systems
Related tips
- Switch matrix dead after an under-playfield adjustment with power on
- Fixing a dead switch column on the CPU board
- Fixing a dead switch row on the CPU board
- Switch column (drive) circuit on the CPU board
- One switch column dead: parts to check in order
- One switch row dead: parts to check in order
- Whole switch column dead after working under the playfield
- Whole switch column dead and board fails the jumper test: column transistor
Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Three, Clay Harrell