Spare diodes to stock
High-voltage section: a 140 V zener, 1N5275A or 2EZ140. General use: 1N4004 and 1N4148 (or 1N914). The MPU reset zener at VR1 is a 1N959B (8.2 V, 1/2 W), which is no longer made; fit a 1N4738A (8.2 V, 1 W) or a 1N4739A (9.1 V), which holds reset low slightly longer.
Systems
Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part One, Clay Harrell (pinrepair.com)