Testing lamp matrix rows with a test socket

Steps

• Remove the backglass and lower the display panel; turn the game on and enter the All Lamps test.
• Unplug 1J6 and 1J7.
• Clip a lead from 1J7 pin 1 (rightmost facing the board) to one lug of a working #555 socket and bulb.
• Clip a second lead to the other lug, with a 1N4004 on its free end, banded end pointing out.
• Touch the diode end to each pin of 1J6 in turn: the bulb should flash on each.
• No light, or a steady bright light, means that row's TIP122/102 is bad (or the diode is reversed).

Systems

• Williams System 11
• Williams System 11A
• Williams System 11B
• Williams System 11C

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
• A row or column of lamps stuck on and very bright
• Whole lamp column works only intermittently: reflow the board header
• Lamps in two columns light together in single lamp test: failed lamp column transistor
• System 11 lamp matrix
• Row or column error: CPU board or playfield?

Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Two, Clay Harrell (pinrepair.com)