>2) What are the differences between the 4000VLC and the 4000-500? Are there
>likely to be some serious gotchas in there?
The VLC (as you know) is small, uses one low profile SCSI disk internally,
has an external SCSI connector, supports a max of 24MB or memory
and weighs in at 6 VUPs or so. There is no real expansion
available.
A VAX 4000-500 is bigger (coffee table size), usually comes with DSSI drives
(although it can use SCSI with the right additional h/w) can have many disks,
supports more memory (512MB max - 32MB min!) and runs at 24VUPs on
a bad day (more if it is really a -700A or 705A). DSSI is available for
storage and the box has a Q-bus.
Whether any of this matters or not depends on what the VAX is supposed
to do. If they wanted an OpenVMS compute engine, almost any cheap
Alpha would eat both of the above for breakfast, so I assume that there
is either a software constraint (e.g. VAX-only 3rd party s/w) or a hardware one
(must use this Q-bus interface card).
Antonio
Does anyone here have access to one the model 723 floppy drive testers with the analog/alignment attachment (option R)? If so can you send me the pin out of the I/O cable for analog attachment? I think there's only six or eight leads on it?
Joe
>From: "Peter C. Wallace" <pcw(a)mesanet.com>
>
>On Wed, 25 Sep 2002, Patrick Rigney wrote:
>
>> > Better still, if you are testing the cards one at a time with an
external
>> > supply, tack on a 5V (set to 5.5 or so) crowbar on the output side of
the
>> > local 5V regulator -- no cut traces, only tacking on 2 wires
>> > temporarily...
>> >
>> > Peter Wallace
>>
>> Peter, yeah, this seems like an easy approach. Question: could a simple
>> 6.2V Zener be installed reverse-biased from the 5V regulator output to
>> ground? Seems like you'd want inline fuses between the unregulated
supply
>> and the backplace as well for this kind of test...
>>
>> Patrick
>>
>>
>
> You would have to have a monster zener to be safe, probably 50 W or
>so. Those arent that common. A crowbar circuit stolen from another supply
or a
>home made one would be better than a zener.
>
> Instead of a crowbar (that usually use SCRs), You could also use a
>5.6v or so shunt regulator made with a big (20A) power transistor and a 5V
>10W zener...
>
>Peter Wallace
>
>
Hi
I think you are all a little paranoid. Regulators rarely
fail in storage. If it is blown, it most likely blew while
the power was on and any damage has already long since been done.
That being said, there is a failure that can happen in
storage that is related to the regulation. Many regulators,
especially the TO-3 types need the screw holding them to
the board to have a vary good connection. If this is
bad, the voltage will go unregulated and it will over
voltage. You should remove and check under these screws
to look for corrosion and clean the surfaces. I recommend
a star washer between the PCB and nut/washer. This should
be checked on any electronics that has been stored.
Often this is a good point to restore some fresh
heatsink compound as well. The old dry stuff is less
effective.
The most common failure is the old electrolytics and
the tantalums. I've seen flames from a blown tantalum.
If you connect a voltmeter to the output leads of any
regulators and watch the voltage as you bring the line up
with a variac ( adjustable auto-transformer ), you should
be able to catch any over voltage before it does any harm.
( note: don't use a variac on a switcher supply! )
Later
Dwight
> Dunno whether this is on-topic or not, apologies if not. Someone at
> my institute needs access to a VAX 4000-500 or similar series machine for a
> proposal for some project work. I intend to loan my Vax 4000 VLC to them,
> but:
>
> 1) Does anyone near San Antonio Texs, have a qualifying machine that they'd
> like to unload permanently, hopefully at a reasonably good price?
I have a VAX 4000-500 I'm looking to sell, but I'm in Plano,
Texas (northern suburb of Dallas).
--
Eric Dittman
dittman(a)dittman.net
Check out the DEC Enthusiasts Club at http://www.dittman.net/
Hi,
I recently accquired a really, really random assortment of RSTS manuals,
>from V06B up to like V9.6 or so, and I'm attempting to make sense of what
portions of docsets I have parts of.. If anyone has extra manuals, that'd
rock, but I also could really use copies/scans/etc. of the documentation
directories, since the only one I have is for V7.1 haha
Will J
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I picked up an ordinary Fujitso KB at a thrift shop that had an adapter on the
end of the cable. It's a small plug and the only markings on it were the
common I/O arrows on the business end. One side is the regular F 5-pin Din
but the male side is about halfway between a regular din and a PS/2 sub.
It is in a 6-pin configuration but the pins are much thinner than usual. It only
has 4 pins which would square with the 5v, grnd, clock, data requirements
but it could have a pin(s) broken off since they're fragile and protrude from the
shell about 3/8". Clockwise the 1 and 3 are missing. There's no center lock.
Anyone have any idea of what this might be for ?
Lawrence
lgwalker(a)mts.net
bigwalk_ca(a)yahoo.com
Hi
Chris Groessler and I have been working with the
CPM-8000 images that we found on the unofficial
CPM page, along with manuals and such found elsewhere.
Last night, I was able to get the CPM-8000 prompt
and execute both commands that I tried ( DIR and USER ).
There are still some minor issues but things should be
moving right along ( why can't programmers realize
that initializing variables is an important part of any
program? ).
I want to give thanks to Hans, without the hardware
manual he scanned, I wouldn't have been able to figure
out the address decoder PROM in my Olivetti M20 and
find out how to bring my machine up to 256K of RAM
( needed by CPM-8000 ).
We still have some work to do ( building up the
disk with all of the files ) but it looks like a
down hill trip from here.
Later
Dwight
All good advice so far -- but one caution I forgot.
My experience is that the CMOS chips from this period are THE MOST STATIC
SENSITIVE chips that there are.
It is much easier to damage these whith inappropriate handling than any
modern stuff.
Use paranoid static handling precautions.
Since I usually work on these machines on those cold (dry) winter days when
static forms easily,
I also use a humidifier in the room where I work.
-Rob
-----Original Message-----
From: cctalk-admin(a)classiccmp.org [mailto:cctalk-admin@classiccmp.org]On
Behalf Of J.C. Wren
Sent: Tuesday, September 24, 2002 8:08 PM
To: cctalk(a)classiccmp.org
Subject: RE: Altair-what do I do first
A less painful way may be to lift the output pin of the regulator
>from its
via. Or (and this is evil, but works, and is can be better than losing all
your unsocketted chips), cut the trace after output of the regulator. You
can always use a piece of foil tape or wire to effect a repair. This may
detract from the ultimate value of the board, but you're far less likely to
wreck it than removing irreplacable socketted chips.
--John
-----Original Message-----
From: cctalk-admin(a)classiccmp.org [mailto:cctalk-admin@classiccmp.org]On
Behalf Of Tony Duell
Sent: Tuesday, September 24, 2002 20:24
To: cctalk(a)classiccmp.org
Subject: Re: Altair-what do I do first
>
> Good move -- don't plug it in yet.
_Neve_ plug in a classic computer without checking it first!
[Good advice on electrolytic caps deleted]
> In any case, detach everything from the power supply and check it out
first.
> Unfortunately, Altairs have no connectors for this, so you will have to
> desolder the wires.
> Some suggest powering it up slowly on a variable transformer, but I have
not
> tried that.
>
> After checking out the power supply voltages, unplug all of the cards and
The amin problem with S100 systems is that the PSU lines on the bus are
unregulated. The voltage regulators are on each card. And this means that
a defective regulator _on a card_ will wipe out all the chips on that
card, and may even put high voltages onto the bus lines and damage other
cards.
Therefore, do as suggested and get the unregulated PSU working first.
Then take the cards (one at a time) and remove all socketed ICs. Make a
diagram first, of course if you don't have the schematics/layout diagrams
for that card. You'd better hope that the expensive/rare ICs (CPU, ROMs,
RAM, LSI I/O chips) are socketed.
Then put the (essentially bare) card in the backplane and check the
outputs of the regulators on that card. Repeat for all the cards you
have. Put the ICs back into a card before starting on the next one
(unless you are a lot better organised than me!)
Then, and only then do you put populated cards into the backplane and
start testing logic functions.
-tony
All,
Dunno whether this is on-topic or not, apologies if not. Someone at
my institute needs access to a VAX 4000-500 or similar series machine for a
proposal for some project work. I intend to loan my Vax 4000 VLC to them,
but:
1) Does anyone near San Antonio Texs, have a qualifying machine that they'd
like to unload permanently, hopefully at a reasonably good price?
2) What are the differences between the 4000VLC and the 4000-500? Are there
likely to be some serious gotchas in there?
- Mark
LOL! Well, my parents apparently are willing to agree there's nothing called
too many computers, so long as they are put away nicely, not filling the
garage, spread through the house, etc.. Heh..
Will J
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