Repairing battery corrosion on the CPU board

Steps

• Remove the CPU board and desolder the four leads of the DataSentry battery; discard it.
• Cut off any part with green or grey leads, keeping the lead long, then heat each pad, pull the lead, add fresh solder and clear the hole with a solder sucker.
• Check the edge fingers; green fingers mean the mating connector pins must be replaced.
• Sand all green or grey areas, fingers included, with 220 grit until bright copper shows.
• Scrub with a 50/50 white vinegar and water mix, rinse with water, then rinse twice with 99% alcohol.
• Tin sanded fingers and traces with solder, wiping while hot.
• Fit new parts (sockets for any chips), but no on-board battery, and re-pin any corroded connectors.

Battery leakage is caustic potassium hydroxide; wear gloves and eye protection when cleaning a corroded board.

Systems

• Gottlieb System 1

Related tips

• Replacing the CPU battery with a remote AA pack
• Memory capacitor or battery does not hold settings
• Using a memory backup capacitor instead of batteries
• Judging battery corrosion damage
• System 1 CPU board connectors
• Aftermarket System 1 CPU boards
• CPU connectors that fail most
• The CPU to driver board harness

Source: Gottlieb System 1 Pinball Repair from 1977 to 1980, Clay Harrell (pinrepair.com)