The top 6-pin .156" connector on the 80B power supply is browned or burnt, and boards lose +5 V.

Burnt +5 V output connector on the 80B power supply

Cause: 12 V comes in on the lower 6-pin connector and +5 V leaves on the top one, each pin feeding a backbox board, so the output connector carries heavy current and overheats.

Fix

• Replace the board's .156" header pins.
• Repin the housing with Molex Trifurcon crimp pins; the original housing can be reused.

Systems

• Gottlieb System 80B

Related tips

• Ground mod step 2: repin the power supply to CPU power cable
• Burnt GI connectors on the power supply (System 7, Hot Tip, Lucky Seven)
• Connector stock for burnt-connector repairs
• Replace the 3J6 logic power connector
• Replace CPU board power connector 1J2
• Use crimp-on pins, ideally trifurcon, when re-pinning connectors
• Molex crimp pin part numbers
• Card-edge connectors are System 80's weak point

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