Bench-test an 80/80A power supply in the game, part 2

Steps

• Power off and connect the cable from power supply J2 to the CPU board's A1-J1.
• Switch on and read TP4 against TP3.
• If +5 V falls, try the trim pot; if it stays below 4.8 V, the load or supply needs fixing.
• Power off, plug in power supply J3 (displays and playfield) and, if you like, CPU A1-J2/J3 (displays) and A1-J5 (slam and test switches; not needed after the slam mod).
• Switch on and recheck TP4, TP1, TP2 and TP5.

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)