Both halves of the power supply limit their current

In the 60 V section, R4 and Q2 cut back pass transistor Q1 if too much current flows. In the 5 V section, R12 (0.33 ohm) senses current into the regulator's pins 2 and 3 and lowers its output. A shorted load therefore shows up as a low output voltage rather than a blown part.

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

• Gottlieb System 80
• Gottlieb System 80A

Related tips

• 80/80A power supply semiconductors
• 80/80A power supply capacitors
• Check power supply outputs with the output cables unplugged
• Power supply ripple and regulation checks
• 80/80A power supply test points and connector pins
• Typical voltages inside the 80/80A power supply
• Power supply output wrong
• Game does not power up properly

Source: System 80 Service Manual, Gottlieb