Using the "T" test PROM

With the test PROM (or its 2716 image on an adaptor) the game boots to attract mode normally. Starting a game fires the three sounds, outhole, knocker, outhole and coils 6-8, pulls in the Q relay for two seconds and runs all 36 lamps in order. After that each playfield switch toggles a lamp or fires a coil; the slam or outhole switch ends test.

Systems

• Gottlieb System 1

Related tips

• The Z23 game PROM
• Diagnostics run without the game PROM
• Dragon: game PROM letter
• Genie: game PROM letter
• Torch: game PROM letter
• Spare chips for System 1 boards
• The six Rockwell "spider" chips on the CPU board
• Which spider chips fail and why

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