What the Game Over (Q) and Tilt (T) relays do

Both relays are under the playfield. The Q relay pulls in for the whole game, powering the flippers, pop bumpers and slingshots and turning off the Game Over backglass lamp. The T relay pulls in on a tilt until the ball drains, cutting coil, flipper and CPU lamp power and lighting the Tilt lamp. Being exposed, they get knocked out of adjustment easily.

Systems

• Gottlieb System 1

Related tips

• How the Tilt and Game Over lamps are switched
• What happens when the T relay pulls in
• What the Q relay contacts switch
• Hold the Q relay in to test flippers and bumpers
• None of the CPU controlled lamps light
• Pop bumper or slingshot locked on or dead
• No CPU controlled lamps light
• Backbox or playfield GI always off

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