The test stops before the burst of three flashes (U5) or four flashes (U6).

Test EPROM stalls at the display or lamp/solenoid RIOT

Cause: The RIOT itself or its select logic. A stuck select line can make the wrong RIOT answer; the test catches this by writing an ID to each.

Checks

• Swap in a known good 6532.
• Check the RIOT select circuitry.

Fix

• Replace the failed RIOT or select chip.

Systems

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

Related tips

• Test EPROM stalls before the RAM pass flash
• System 80 test EPROM LED flash codes
• Swap the three 6532 RIOT chips when a CPU board dies
• Test EPROM: no long flash, or LED stuck on
• Replacing U2 and U3 with one 2764 EPROM
• Ways to fit EPROMs at U2/U3
• Which System 80 test EPROM image to use
• Bench setup for the System 80 test EPROM

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