Coil, CPU lamp and GI supplies

Coil power is 25 V AC through a 5 A slow-blow fuse and a bottom panel bridge, giving about 25 V DC unregulated. CPU lamps get 8 V AC through a 5 A slow-blow fuse and a bridge, about 6 V DC under load (it falls as more lamps light). GI is 6.3 V AC straight from the transformer through a 10 A normal-blow fuse.

The bottom panel carries 120 volt line power; unplug the game before touching the transformers, line filter or fuse block.

Systems

• Gottlieb System 1

Related tips

• Spare diodes, capacitors and other parts for System 1
• What is on the System 1 bottom panel
• How power reaches a System 1 game
• Testing a bottom panel bridge rectifier
• Replacement bridge rectifiers
• The two System 1 transformers
• All CPU controlled lamps are dim
• None of the CPU controlled lamps light

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