Testing lamp matrix columns with a test socket
Steps
- Remove the backglass and lower the display panel to reach the CPU board.
- Unplug 1J6 and 1J7 (lower right of the CPU board), turn the game on and enter the All Lamps test.
- Clip a lead from 1J6 pin 1 (rightmost pin facing the board) to one lug of a working #555 socket and bulb.
- Clip a second lead to the other socket lug, with a 1N4004 on its free end, non-banded end pointing out.
- Touch the diode end to each pin of 1J7 in turn: the bulb should flash on each.
- No light, or a steady bright light, means that column's TIP42 is bad (or the test diode is reversed). Test the transistor.
Systems
Related tips
- System 11 lamp matrix basics
- Lamp matrix fault with good transistors: 0.4 ohm resistors
- Lamp matrix still wrong after replacing transistors: upstream parts
- Whole lamp column works only intermittently: reflow the board header
- A row or column of lamps stuck on and very bright
- Lamps in two columns light together in single lamp test: failed lamp column transistor
- Quick lamp row test: ground the row driver tab
- System 11 lamp matrix
Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Two, Clay Harrell (pinrepair.com)