None of the CPU controlled lamps work.

No CPU controlled lamps light

Cause: No DC lamp supply: fuse, bridge, an open T relay contact, or a shorted driver Q2 holding the T relay in.

Checks

• With the game on, look for 6-8 V DC at the lamp sockets, on both lugs; power on only one lug means a bad bulb.
• Check the bottom cabinet 5 A slow-blow lamp fuse and the bridge nearest the copper ground strap.
• Check that the T relay is not energized and its actuator plate is still on its frame.
• Test driver Q2.

Fix

• Replace the fuse, bridge, Q2, or refit the relay plate.

Systems

• Gottlieb System 1

Related tips

• None of the CPU controlled lamps light
• How CPU-controlled lamps are driven
• Testing a CPU lamp circuit by grounding its driver
• Finding which transistor drives a lamp
• Shorted lamp sockets kill MPS-A13 drivers
• Backbox or playfield GI always off
• Groups of four lamps or single lamps misbehaving
• Coil, CPU lamp and GI supplies

Source: Gottlieb System 1 Pinball Repair from 1977 to 1980, Clay Harrell (pinrepair.com)