WPC CPU board LED meanings

Normally the top LED (blanking) is off, the centre LED (diagnostic) flashes and the bottom LED (+5 V) is lit. If the centre LED blinks once at power-on the ROM U6 is bad, twice the RAM U8, and three times the custom chip U9.

Systems

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

Related tips

• WPC CPU board LEDs at power-on
• Reading the CPU board LEDs at power-on
• What a WPC game reset is
• CPU diagnostic LED blinks a code instead of flashing steadily
• What is on the WPC CPU board
• Won't boot after a ribbon cable was fitted one row off: unplug boards to find the damage
• What fails on a WPC CPU board
• Resets: +5 V at the driver board test point is low

Source: Pinball Machines: How They Work & Troubleshooting, Norbert Snicer