Old black masked ROMs fail from tarnished legs

The silver-plated legs of the original masked ROMs blacken with silver oxide against the tin sockets, conduct poorly and snap easily. These ROMs are no longer made; replace them with burned EPROMs and cover the EPROM window with a label.

Systems

• Bally MPU AS-2518-17
• Bally MPU AS-2518-35

Related tips

• Masked ROM numbers: keep the set matched
• 9332 masked ROMs can be replaced by 2532 EPROMs as-is
• Why the MPU has ROM jumpers
• How the first-flash ROM test works
• After the test EPROM: refit the game ROM and count flashes
• Get the MPU booting before you change any ROM jumpers
• Bally -35 MPU jumper settings by ROM type
• Leave the ROM jumpers alone until the LED flickers

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