System 80B display board connector A4J1

Pins 1 and 2 are the 6.2 V AC filament feed and return. Pins 3 and 4 bring 32 V AC that the board rectifies into -45 V and -15 V DC. Pin 6 is reset (from CPU A1J2 pin 24, which also goes on to the sound board), pin 7 +5 V DC, pins 9 and 10 LD1 and LD2, pins 11 to 18 data 0 to 7, and pin 19 ground.

The 80B display board turns 32 V AC into -45 V and -15 V DC; switch off before touching it and probe carefully with the power on.

Systems

• Gottlieb System 80B

Related tips

• System 80B display driver chips 10939 and 10941
• System 80B displays stuck in reset
• System 80 schematics' 'offset' voltages are DC bias for the display filaments
• Score display boards by generation
• Alphanumeric display board MA-644 parts
• Two alphanumeric display boards: glasses do not swap between them
• Guarding the fill tip on the back of a score display

Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part Two, Clay Harrell (pinrepair.com)