One of the +60, +42, +5 or +8 V outputs is missing or incorrect.

Power supply output wrong

Cause: A failed part in the section that makes that voltage, or a short between the pass transistor or its hardware and the frame.

Checks

• Measure each output at the labelled test points and compare with the typical values on the schematic.
• Check that the frame-mounted transistor case and its screws are insulated from the frame.
• Make sure no component or connector lead touches the frame.

Fix

• Trace the bad section using the schematic and replace the failed part; restore any missing insulator.

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

• Check power supply outputs with the output cables unplugged
• 80/80A power supply semiconductors
• 80/80A power supply capacitors
• How the 80/80A power supply makes its four voltages
• Both halves of the power supply limit their current
• 80/80A power supply test points and connector pins
• Power supply LEDs show voltage present, not correct
• The 5 V output has a crowbar for overvoltage

Source: System 80 Service Manual, Gottlieb