Master display board versions

The common six-digit master display board is the D-8000, with UDN6184A and UDN7180A driver chips and card-edge display connectors. The D-8168, used now and then from Flash to the Firepower era, swaps the UDN chips for individual MPS-A42/MPS-A92 transistors and is easy to test. Some six-digit boards used 22-pin NE584/NE585 drivers, which are obsolete and practically unrepairable. Seven-digit games use a master board with ribbon cables to the displays.

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A
• Williams System 7

Related tips

• Which UDN6184 drives which display
• UDN display driver chips
• Using a logic probe on the display board safely
• One score display dead
• Test MPS-A42 and MPS-A92 display transistors
• Find a shorted display glass that blows F1
• Four digits missing on the player 2 and 3 displays: bad driver IC12 on the master display
• Bottom segments missing and master display resistors burning: shorted display glass

Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)