How the A2 +5 V supply works
A2 takes the raw 12 V DC and regulates it to +5 V with an LM338 on the big heat sink, set by a 500 ohm trimmer at R3. The unregulated 12 V just passes through the board and back out.
Systems
Related tips
- Swapping A2 for a switching 5 V supply
- Set the 80B +5 V after replacing the trim pot
- +5 V wrong or drifting; resets after a few minutes
- 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)