Swapping A2 for a switching 5 V supply

Steps

• A switching supply (arcade or PC type) shuts itself off on a fault and protects the logic, unlike the stock A2.
• On the A2 harness, J1 pins 1, 4 and 5 are the raw 12 V: join them together and connect them to nothing else.
• J1 pins 2, 3 and 6 are ground; J2 pins 1 to 8 are +5 V out to the boards.
• Wire the new supply's 5 V and ground to those pins and set it to about 5 V at the CPU board.

Line voltage is present in the power box and transformer panel; unplug the game first.

Systems

• Gottlieb System 3

Related tips

• How the A2 +5 V supply works
• A2 has no overvoltage shutdown
• Checking and setting +5 V at the CPU board
• A2 and A3 plug wire colours

Source: Repairing Gottlieb System 3 Electronic Pinball Games from 1989 to 1996, Clay Harrell (pinrepair.com)