How the 80/80A power supply makes its four voltages
The supply has two independent halves on a common ground. The high-voltage half takes 60 V AC on A2-J1 pins 7 and 8, rectifies it with CR1-CR4, regulates it to +60 V DC through pass transistor Q1 with zener CR5, and drops +42 V DC from the 60 V with zener CR6 and R5. The low-voltage half takes about 12 V DC from the bottom board on A2-J1 pin 1 and regulates it to +5 V DC with a 723 regulator and pass transistor Q3, plus +8 V DC for the display offset from CR7 and R10.
The display supply carries 60 V DC (and 42 V DC); keep fingers off the power supply and display boards while the game is on.
Systems
Related tips
- Typical voltages inside the 80/80A power supply
- 80/80A power supply semiconductors
- 80/80A power supply capacitors
- 80/80A power supply test points and connector pins
- Power supply LEDs show voltage present, not correct
- Check power supply outputs with the output cables unplugged
- Power supply ripple and regulation checks
- Power supply output wrong
Source: System 80 Service Manual, Gottlieb