Reset and clock are good but the board does not boot.

CPU address and data line check

Cause: Failed spider chips.

Checks

• Probe TC1 pins 1-13 for pulsing.

Fix

• If they pulse and the bench LED still never lights, or if they do not pulse, the spiders are bad and a replacement CPU board is needed.

Systems

• Gottlieb System 1

Related tips

• Using an LED to see a bench CPU boot
• Dead CPU board: first checks
• Aftermarket System 1 CPU boards
• Check the TC3 jumper plug on the CPU board
• Powering a System 1 CPU board on the bench
• The six Rockwell "spider" chips on the CPU board
• Swapped U4 or U5 spider still does not work
• Spare chips for System 1 boards

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