Solenoids lock on and burn.

Coils lock on when the switch matrix connector is loose

Cause: The playfield switch matrix plug on the CPU board, A1-J6, is unplugged or making poor contact. Because of the way some games tie coil firing to the switch matrix, the CPU then holds coils on.

Checks

• Check A1-J6 is fully seated and its pins are not burnt or loose.

Fix

• Repin or repair the connector before running the game.

Systems

• Gottlieb System 80

Related tips

• CPU board connector A1J6 (playfield switch matrix)
• System 80 CPU board connectors and what they carry
• Which CPU connector housings can be reused
• CPU board connector A1J4 (to the driver board)
• CPU board connector A1J5 (coin door)
• Card-edge connectors are System 80's weak point
• Clean corroded card-edge fingers and connectors
• Molex housings and pins for the System 80 CPU connectors

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