Driver board supply test points and normal readings

+5 V: TP2 (TP101 on WPC-95), 4.92-5.1 V. +18 V unregulated lamp supply: TP8 (TP102 on WPC-95), 16-20 V; if low check BR1 and C6/C7 (D11-D14 and C11/C12 on WPC-95). +12 V regulated: TP3 (TP100 on WPC-95), 11-13 V; it is made from the 18 V through a 7812 regulator at Q2, so good 18 V with low 12 V points to Q2. Readings taken in attract mode do not prove the supply holds up under load.

Systems

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

Related tips

• Random coil firing or slam tilt from weak 12 V (notably Theatre of Magic)
• WPC-89/WPC-S driver board LEDs and test points
• WPC-95 driver board LEDs and test points
• Driver board LED1 off: switch matrix 12 V missing (WPC-S and earlier)
• Driver board LED5 off (+20 V flashers)
• Driver board filter capacitors wear out
• Voltages made by the WPC power driver board
• Bridge rectifiers to use on WPC-S and earlier driver boards

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