Installing a memory back-up capacitor

Steps

• Remove the battery and clean any corrosion first.
• Drill a small hole next to the negative battery pad for the cap's second lead.
• Fit the cap, the lead marked with the black stripe being negative, and bend the leads to hold it.
• Solder it, and run a short wire from the lead in the drilled hole to the other battery pad.

Systems

• Bally MPU AS-2518-17
• Bally MPU AS-2518-35
• Stern MPU-100
• Stern MPU-200

Related tips

• Knocker fires 'randomly' in play: no memory battery, so every game sets replays
• Cut the original MPU battery off right away
• Corrosion under MPU J4 can destroy every chip
• Reset section parts typically ruined by battery corrosion
• Repairing battery corrosion on the MPU
• Removing corroded chip sockets
• Fitting a remote AA battery pack
• Repair battery corrosion before chasing MPU flash codes

Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part One, Clay Harrell (pinrepair.com)