What fails on a WPC CPU board

The ASIC at U9 rarely fails, though battery leakage or prying it out without the right tool often damages its socket. The switch matrix parts on the lower third of the board seldom stop it booting. The game EPROM rarely fails. The U8 6264 RAM is very static sensitive and fails easily, causing all sorts of odd behaviour. The TTL chips U1, U2 and U3 across the top can fail. The U10 reset chip (34064) and U5 clock chip (74LS14) rarely fail. Broken traces from earlier repairs are common.

Systems

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

Related tips

• What is on the WPC CPU board
• Running a WPC CPU board on the bench
• WPC CPU board versions and where they fit
• Bench-check the WPC CPU switch matrix circuit
• WPC-S and WPC-95 CPU boards need the matching security PIC
• Pre-WPC-S CPU EPROM size jumpers W1 and W2
• Country DIP switch settings on WPC-S and WPC-95 CPU boards
• Country jumpers W13 to W18 on pre-WPC-S CPU boards

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