Player 1 shows odd values in attract mode, only some of its digits work in display test, digits flash during lamp test, and scoring and some coils misbehave.

Garbled player 1 display and strange play from a bad 5101 RAM

Cause: A failing or too-slow 5101 RAM at U8, even though the power-on test passes it.

Checks

• Replace U8 with a known-good, fast enough 5101.

Fix

• Fit a 5101 rated at least 650 ns or faster for a Bally board.

Systems

• Bally MPU AS-2518-35

Games

• Silverball Mania

Related tips

• Seven flashes but no attract mode
• Two flashes only: U8 5101 RAM
• Six flashes only: 43 V, U10 or U14
• Use a fast enough 5101 RAM
• One flash only: U7 6810 RAM
• Logic probe states in attract mode: U9 6800 and U12 555
• Logic probe states in attract mode: U16 9602 and U15 MC3459
• Game locks up entering bookkeeping after a battery change

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