After fitting a replacement CPU board the game boots and plays only with the coin door diagnostic button connector (CN14) unplugged; with it plugged in the game stops shortly after power-up.

New CPU board locks up when the coin door buttons are plugged in: reseat the PIA

Cause: A PIA on the CPU board was not making good contact in its socket. A PIA test chip flagged the PIA at 11B; a bent CPU pin was also found but straightening it made no difference.

Checks

• Unplug every connector except power and plug them back one at a time to find which one stops the boot.
• Check that CN13 (grounds) and CN14 (diagnostic buttons) are not swapped.
• Look for bent pins on the socketed chips, then run a PIA test ROM or chip if you have one.

Fix

• Remove and reseat the PIA (11B here) firmly in its socket, then retest with the coin door buttons connected.

Systems

• Data East CPU Version 3

Games

• Adventures of Rocky and Bullwinkle and Friends

Related tips

• All lamps come on, flipper fuse blows and the game won't boot: failed replacement NVRAM
• Replacement CPU board won't boot with the old processor: socket contact
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• Data East CPU diagnostic test EPROM
• CPU still will not boot after the basics
• Logic probe readings on the matrix connectors of a booted CPU
• Program runs but the PIAs never respond
• Wrong speech and sounds play for callouts: battery-corroded CPU board

Source: Pinball Repair help group!! (Facebook group)