WPC CPU board LEDs at power-on

WPC-S and earlier boards label the CPU LEDs D19 to D21; WPC-95 uses LED201 to LED203. D19/LED201 (blanking) lights at power-on for roughly 3 s (WPC-95: roughly 1 s), then goes out for good; while it is on, no coils can fire. D20/LED203 (diagnostic) then flashes steadily for as long as the CPU is running. D21/LED202 (+5 V) is always on. Only the CPU board LEDs give flash codes.

Systems

• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• WPC CPU board LED meanings
• Reading the CPU board LEDs at power-on
• What a WPC game reset is
• What is on the WPC CPU board
• Factory settings restored at every power-up after new batteries: do a factory reset
• Won't boot after a ribbon cable was fitted one row off: unplug boards to find the damage
• Reboots at start-up and when flipping: flaky power connector to the CPU
• Where the CPU board gets its power

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Three, Clay Harrell (pinrepair.com)