During the I/O test U5's slam-related line does not respond.

RIOT I/O test: U5 and the slam input

Cause: On U5 all of port B and PA0-PA5 are outputs that should pulse; PA6 follows the slam input on PA7. A bad slam input buffer Z26 stops it responding.

Checks

• With the slam input not grounded, PA6 should sit at 0 V.
• Ground the slam input; the line should now pulse like the others.

Fix

• If it does not, check and replace slam input buffer Z26.

Systems

• Gottlieb System 80
• Gottlieb System 80A
• Gottlieb System 80B

Related tips

• 6532 RIOT port pins on the System 80 CPU board
• Swap the three 6532 RIOT chips when a CPU board dies
• Test EPROM stalls at the switch matrix RIOT (U4)
• Test EPROM stalls at the display or lamp/solenoid RIOT
• Which System 80 CPU board goes with which games
• Later single-PROM CPU board won't boot in an early System 80 game
• System 80 and 80A CPU boards swap only with the matching U2/U3
• Making a System 80B CPU board run an earlier game (or the reverse)

Source: Gottlieb System 80 Test EPROM V3.2 (February 2015), Pinitech