there are 3 test points near the cabinet power switch, next to the power leds. You can check for the 5, 12 and 24 voltages there. This is only for the two power supplies on the left wall. As stated already, the mpu has it's own.
When you boot up, power on from left to right, main power, cabinet power, then mpu power(small switch on the mpu. you should see the red light and hear a short beep {as mentioned in previous post). without the beep, Rick is on the right track of course.
Always check the simple things first of course, e.g. power plug into mpu pushed in completely, cf cards inserted fully, and mpu pushed in completely. be sure to have main power off before inserting or removing any boards or cards. I know this is obvious, but I've seen it happen before.
it's cold here, in Canada, so when machines are moved in pickup trucks etc, they get cold. bringing them into a warm house, and turning them on before they warm up and dry out any condensation ruins many components. I always tell people to wait a day, but anxiety gets the better of some poeple.
Thanks,
Wayne