+5vdc regulated logic power.
+12vdc unregulated, often called "unregulated 5 volts" by Williams, because
on the CPU board the unregulated 12 volts gets knocked down to about 5
volts.
+18vdc lamp matrix power (for game controlled lamps).
+28vdc solenoid/flipper power.
+/- 100vdc score display power.
6.3vac General Illumination lamp power.
+50 volts DC (for flippers), Firepower2 and later, via an additional flipper

To check the +5 volts, use a DMM and measure the +5 volts DC at power supply
connector 3J6 pins 7 to 10 (remember J6 pins 11 to 15 are ground). The +5 volts
should measure between 4.9 and 5.2 volts DC.

Check the High Voltage +/-100 volts.Put the DMM's black lead on J5 pin 1 (ground). Put the red lead on J5 pin
3, and between -90 to -105 volts DC should be seen. Now move the red DMM lead
to J5 pin 4, and +90 to +105 volts DC should be seen.

Check the Solenoid Voltage.Put the DMM's black lead on J3 pin 3 (ground). Put the red lead on J3 pin
6 to pin 9, and between 28 to 38 volts DC should be seen