Bench-test an 80/80A power supply in the game, part 1

Steps

• Check every bottom-panel fuse for correct rating and type.
• Unplug every connector from every backbox board, then plug in only power supply J1 and switch on.
• LEDs DS1 (unregulated 12 V in) and DS2 (+5 V out) should both light.
• Measure against TP3 (ground): TP4 +5 V, TP5 8 V, TP1 60 V, TP2 42 V.
• Readings somewhat high are fine (about 48 V at the 42 V point, 65 V at the 60 V point, 8.6 V at the 8 V point), but +5 V must sit between 4.8 and 5.2 V; the trim pot sets it.

The System 80/80A power supply makes about 60 V and 42 V DC for the displays; keep fingers off the board and connectors with the game on.

Systems

• Gottlieb System 80
• Gottlieb System 80A

Related tips

• Parts for the 80/80A power supply rebuild
• Reassemble and set up the 80/80A power supply
• Mandatory 80/80A power supply rebuild
• Recommended extras for the 80/80A power supply
• Test and remove the 80/80A power supply's big transistor
• Original 80/80A power supply design overheats CR7
• 80/80A power supply has 12 V but no +5 V
• Which System 80 power supply boards are interchangeable

Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part One, Clay Harrell (pinrepair.com)