On Sun, 15 Apr 2001, Richard Erlacher wrote:
> Is anbody intimate enough with the VaxStation 2000 to provide a couple
> of details? Here's the deal:
Not really intimate with them, but I have used them to run NetBSD/vax and
Ultrix.
> I snagged a VaxStation 2000 box some time back, mainly for the PSU.
> It turns out that it has a couple of lines, on the 9-pin MOLEX main
> power output connector, the purpose of which is not clear. There's
> one that seems to float at around -6 Volts DC, and another that floats
> at high-impedance, yet, when the one at -6 is pulled to 0 (gnd)
> through a resistor, the previously floating one suddenly has 9 volts
> or so. Do these have a specific purpose that might serve some need
> I'm likely to encounter, or are they just for the DEC folks' features?
> Is there any way to capitalize on them, or should I just leave them
> alone? All I'm after is fairly normal power output, with the added
> benefit of a fan and switch. The +5 and bipolar 12's seem to work
> fine. Spec's would be handy too, e.g. how much current can be drawn
> from each of the supplies and, perhaps from all of them at once?
I think (I'm not positive) this may be related to the nature of the power
supply. I've not actually used them for anything but powering the
components which normally make up a VAXstation 2000. They do have some
interesting qualities, the main one being that they don't work right
unless they've got a load on them.
I've made the mistake of trying to run one diskless--which doesn't work.
As soon as you add a disk drive, then the system goes through it's power
up sequence without problem. DEC did make a diskless version of the
VS2000, but it had a big resistor board that plugged into the internal
drive power cable.
I'm sure someone here can address the actual reasons why the power supply
behaves like this. I think it's a trait of older switching PSUs. But
hopefully my "systems guy" observations provide some useful clues.
-brian.
--- Brian Chase | bdc_at_world.std.com |
http://world.std.com/~bdc/ -----
Being an open and honest guy, in the big "Occupation" box in the center
of the sheet, I had written the same thing that's on my business cards.
"Internet Legend". -- K.
Received on Sun Apr 15 2001 - 15:01:58 BST