First power-up, step 4: add the CPU board one connector at a time

Steps

• Remove every CPU connector except J1, switch on, and read 4.9 to 5.1 V DC across capacitor C1 beside J1.
• Power off, plug in display connectors J2 and J3 (80B has only J2), and switch on: displays should show zeros (80B may show "slam tilt open").
• If the displays stay blank the CPU board is dead and needs repair.
• Power off, check the J5 pins for gray or green corrosion and repin if needed, then plug in J5 (coin door and slam switches).
• On 80/80A the scores should appear after about five seconds; on 80B attract text appears at once. If not, look for a short in the coin door wiring.
• Press the red coin door test button and step to test 18; with all switches open it shows "99".
• Power off, inspect and plug in J6 (playfield switch matrix), and check in test 18 that closing playfield switches shows their numbers.

Systems

• Gottlieb System 80
• Gottlieb System 80A
• Gottlieb System 80B

Related tips

• Dead CPU board: check the reset line first
• Why a System 80 CPU stops running
• Niwumpf replacement CPU board takes about 10 seconds to show scores
• Reset section zener VR1 burnt on a System 80 CPU board
• Replace the System 80 reset circuit with a DS1811 chip
• What the System 80 reset (watchdog) board does
• Game won't boot, or keeps rebooting, because of the reset board
• Displays show 000000 at once and scroll; start does nothing

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