Reset works but the board still does not boot.

CPU board clock check

Cause: No clock from the crystal and U1 spider.

Checks

• TC2 pins 11 and 12 and both crystal legs should pulse on a logic probe or scope.
• With a meter: about 2.8 V at TC2-11, 2.9 V at TC2-12, 0.3 V on the top crystal leg and 0.9 V on the bottom.

Fix

• Try a new 3.579 MHz crystal Y1 (above J1), though it rarely fails.
• No clock with a good crystal means U1 has failed and the board must be replaced.

Systems

• Gottlieb System 1

Related tips

• Using an LED to see a bench CPU boot
• Swapped U4 or U5 spider still does not work
• 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
• Testing CPU input buffers Z29 and Z27

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