After all the backbox plugs were pulled, the game misbehaves or boards get damaged once it is plugged back in.

Backbox plugs swapped after a move

Cause: Many System 3 backbox connectors are the same size with poor keying, so a plug fits an adjacent header.

Checks

• Compare the wire colours at pins 1 and 2 of each plug with the board connector lists; colour is the only way to tell like-sized plugs apart.

Fix

• Label plugs before removal; put each back by its wire colours.

Wrong connections damage the boards. Never unplug or plug anything on the A8 controller or the display with power on.

Systems

• Gottlieb System 3

Related tips

• A2 and A3 plug wire colours
• A5, A6, A8 and A20 plug identification

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