15 Apr
2001
15 Apr
'01
4:17 a.m.
Opps, I made a typo on the URL... Please try this one.
http://www.ubanproductions.com/imlac.html
--tom
Well, I said that I would put up some more pictures of
one of my Imlacs
a couple of days ago, but I got delayed a bit, so here they are now:
http://www.ubanproductions.com/imlacs.html
--tom
15 Apr
15 Apr
9:03 a.m.
New subject: VaxStation 2000 PSU info needed
Is anbody intimate enough with the VaxStation 2000 to provide a couple of
details? Here's the deal:
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?
Thanx,
Dick
11:01 a.m.
New subject: VaxStation 2000 PSU info needed
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(a)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.
6:03 p.m.
New subject: VaxStation 2000 PSU info needed
Back in the early '80's it wasn't uncommon for switchers to malfunction, or,
if
designed somewhat better, to fail to function at all, if no load was present.
This is consistent with DEC's practice of putting out 10-year old technology in
its "current" products. Their rotating memory products were always at least
one, and often three, generations behind the "current" generation in other
makers' products. That ensured maximal profits for DEC shareholders and maximal
bonuses for their execs, though it also ensured last-generation performance or
less for their users.
Dick
----- Original Message -----
From: "Brian Chase" <bdc(a)world.std.com>
To: <classiccmp(a)classiccmp.org>
Sent: Sunday, April 15, 2001 2:01 PM
Subject: Re: VaxStation 2000 PSU info needed
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(a)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.
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