System 11 lamp matrix basics
CPU-controlled lamps (not GI) form an 8 x 8 matrix of 64 lamps on +18 V DC, strobed so each lamp sees about 6 V. TIP42 transistors switch +18 V to the columns; TIP122/102 transistors switch ground to the rows. The TIP42s fail more often because they source current.
Systems
Related tips
- Testing lamp matrix columns with a test socket
- Testing lamp matrix rows with a test socket
- System 11 lamp matrix
- Lamp matrix fault with good transistors: 0.4 ohm resistors
- Lamp matrix still wrong after replacing transistors: upstream parts
- Quick lamp row test: ground the row driver tab
- Whole lamp column works only intermittently: reflow the board header
- A row or column of lamps stuck on and very bright
Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Two, Clay Harrell (pinrepair.com)