New toy: VAX with DECVoice - test-drb@ccmp.vtda.org

22 Jul 2001

On July 22, R. D. Davis wrote:
...
  Anyway, it's now counting down to 3, so,
something's working! :-)
 ...will know more when I can get a terminal attached.  Do all
 VAX-4000/200 machines make a loud fan noise when first powered on, and
 then get much quieter?  Are variable-speed fans being used, and is
 that noise a test of high-speed operation? 
  They are variable-speed fans.  I'm not sure why they do that on
powerup in these machines, but I have seen situations in which
variable-speed fans were in use and, due to the control circuitry,
they didn't have enough power applied to them when the system was
powered up to overcome static friction and get the rotor going.  I'm
guessing that DEC knew about this and designed the control circuitry
to give them a little "kick" at powerup to make sure they're all
running, then spin them down to the speed required by the temperature
of the machine.

          -Dave McGuire