Never plug displays with the power on

Plugging or unplugging CPU J2/J3 or a score display with the game on will likely kill CPU display chips (Z16-Z17, Z13-Z15 or Z18-Z21) and sometimes the display's own driver chip.

The display supply runs at 60 to 69 volts; work on it with the game off and never plug or unplug display connectors with power on.

Systems

• Gottlieb System 1

Related tips

• Power supply bring-up, step 3: displays
• How the Gottlieb fluorescent displays work
• Reviving a faded Futaba display
• Displays are scanned, not lit steadily
• +60 V or +42 V display voltage missing
• System 1 and System 80 six-digit displays interchange
• Wrong-looking digits or bad "1"s
• Dead CPU board: first checks

Source: Gottlieb System 1 Pinball Repair from 1977 to 1980, Clay Harrell (pinrepair.com)