The A8 dot matrix controller board

A8 has its own 65C02 and EPROM for animations and talks to the CPU over a ribbon cable. It also takes +5 V and +20 V DC, and rectifies 58 VAC and 95 VAC on board into the display voltages using MJE15030/MJE15031 and 2N5551/2N5401 transistors with 1N4759, 1N4758 and 1N4742 zeners.

The A8 controller makes roughly +62 V, -100 V and -112 V for the display; keep hands off it with power on.

Systems

• Gottlieb System 3

Related tips

• Dot matrix dark: +62 V missing
• DMD controller LED stays on
• Garbage on the dot matrix at power-on
• Never hot-plug the A8 board or the display
• Rebuilding the A8 high-voltage section
• A5, A6, A8 and A20 plug identification
• Nonsense message at boot, game stuck in a loop
• Display works in a Williams game but not in System 3

Source: Repairing Gottlieb System 3 Electronic Pinball Games from 1989 to 1996, Clay Harrell (pinrepair.com)