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'00 VF4 wont power up


Jul 22, 2010
Stillwater, MN
Looks like it is going to be one of those days...
Went to power up one of our '00 VF4's this morning, and when I pressed power on, the enclosure light turned on, but no "beep" was heard to indicate normal power up. The monitor isn't on, and the stack light is not flashing. No beeps are heard when pressing any keys on the keypad. I opened the control cabinet, and no breakers are tripped. Phasing LED is green, and the vector drive has power. What are the next steps in diagnosing? I do have an identical machine from which I can borrow parts to troubleshoot.

Are you good being that close to live, high voltage electronics? Insert standard warning here about lethal voltages inside that cabinet. This ain't no messin around neither. Not only do you have the incoming line but, that 320V DC bus going to the drive amps will bite and not let go like AC does. I blew the tip off an oscilloscope probe once on that bus. The grounding ring just tapped a screw and the probe exploded like a firecracker in my hand. I shut it down and walked away after that one.

Your next check and very likely culprit is going to be the DC power supply. It supplies 12V and 5V to all the boards. Same job as a computer power supply. You'll see the cables going to the logic boards. Black is ground. You should measure 12V, +5 and -5. If it's working, you should also be able to see some of the check and fault lights on the various boards in the triple stack.