Restoring brightness on 4, 6 and 7 digit display boards

Steps

• Treat every display at once so they match.
• Move the lower end of the 10k resistor that sits between both UDN6118s to the top leg of the .01 uF capacitor (some boards have a hole drilled for this), fitting a new 10k.
• Reflow all joints on the glass tube pins, on both UDN6118 chips and on the chip of the four-digit display.
• Replace both .01 uF 100 V capacitors.
• Replace the 1 uF 100 V electrolytic with 2.2 uF 100 V on a four-digit display, or 4.7 uF 100 V on a six- or seven-digit display.

System 80/80A displays run on about 60 V DC; switch the game off before unplugging or touching a display or its connector.

Systems

• Gottlieb System 80
• Gottlieb System 80A

Related tips

• Missing segment on one or more score displays
• Missing digit on one or more score displays
• Display fault: board or display?
• One six-digit display completely dead
• System 3 CPU board reset circuit modification
• Gottlieb System 80: bottom segment missing on one display that follows it: replace Z1
• Display chips on the CPU board fail after swapping displays
• Brightening a dim Futaba display with a 9 V battery

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