VAX 780 on eBay

Paul Koning paulkoning at
Mon Jan 3 12:58:06 CST 2022

The discussion about 3-phase made me check some documentation.

The drive I remembered that uses 3-phase power is the RP04.  I remember a warning to the installer to verify the phase order; if that's wrong the drive will try to spin up in the wrong direction, which might partially unscrew the pack from the spindle -- that would be bad if the heads tried to load.

The RP07 is also 3-phase.  Other drives I looked at are 1 phase.

I also looked at some CDC 6000 series docs.  Those used 400 Hz 3 phase for supplying the CPU and peripheral logic.  The CPU cabinets also take 3 phase mains power for the  compressors (for the Freon cooling system).  Curiously, the 1964-era 6603 disk drive uses only 400 Hz power.  I wonder if that feeds the spindle motor, or if that was a DC motor?  And the 626 tape drive wants 3-phase mains power.


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