3 Nov
2006
3 Nov
'06
6:09 a.m.
I'm not one that ever advocates tearing apart classic gear. But in this case
I think it's warranted and I'd like some advice.
I have more than a few RA81's that are all clearly labled "BAD HDA", and the
person I got them from confirmed "these are all dead". I grabbed them
anyways as they had to be taken as part of "the deal".
I am not familiar with these drives at all. From what I've heard over the
years, they have a fairly high failure rate and thus people who use them are
often looking for HDA assemblies. This makes me think that it's unlikely
that I'll be able to just pull the bad HDA's out and obtain good ones to put
in. Plus I don't need this many drives at all, so I think it's time to tear
them apart and scrap them.
Since I don't know anything about RA81's yet (have never used them or opened
one up), and because I do intend to keep one or two of the drives running (a
few don't say "bad hda" on them), can someone tell me what parts I should
scavange off the dead ones that are worth keeping as spares? I know the
obvious like the light bulbs and drive select plugs, but what about
components on the inside that "those in the know" would advise I not just
pitch with the drives?
Lastly, are the casings for the RA81's mostly steel, or aluminum? I'm
pondering putting them in the van and taking to a scrap metal dealer. I
wouldn't do this, but they are clearly dead, HDA's not likely to appear, no
one wants them, and I need the space.
Jay West
3 Nov
3 Nov
3:59 a.m.
Jay West wrote:
Since I don't know anything about RA81's yet
(have never used them or
opened one up), and because I do intend to keep one or two of the drives
running (a few don't say "bad hda" on them), can someone tell me what
parts I should scavange off the dead ones that are worth keeping as
spares?
Hmm, I seem to remember list wisdom was that the spindle sensors on the
underside of the drives go bad all the time - it's certainly worth rescuing
those, but are you sure that the reason for the 'bad hda message' isn't
something like this (rather than catastrophic mechanical failure or something
which would require opening the drive case up?).
I seem to recall that we replaced a spindle sensor on one of our drives with a
more modern part (I seem to recall doing a bit of hacksawing and gluing to it
so that it'd mount on the drive case properly)
I certainly would have thought that it's worth your while to make up as many
good units as possible out of the bits, unless you know that the failures
aren't fixable already. As I recall the drive's on-board diags are pretty good
(as are the manuals - I'm pretty sure there were comprehensive test procedures
in there)
but they are clearly dead
How do you know?
cheers
Jules
5 Nov
5 Nov
10:19 a.m.
Jules wrote....
I certainly would have thought that it's worth
your while to make up as
many good units as possible out of the bits, unless you know that the
failures aren't fixable already. As I recall the drive's on-board diags
are pretty good (as are the manuals - I'm pretty sure there were
comprehensive test procedures in there)
Yes, I'm aware of the diags. I have
read the manuals quite some time ago and
saw the cute built-in "console port" and such.
I had written...
> but they are clearly dead
To which Jules responded.
How do you know?
Because the collector on this list who gave me all the RA81's said they were
tested and dead, and he put the "Bad HDA" tags on the front. But you're
right I shouldn't take his word for it. I should retest them all.
Jay
2:54 p.m.
Among the problems back around 85-86 was a problem with breather filter glue
creep causing head contamination and crashing starting with head 13... the
bottom physical head.
I replaced a bunch when I was in Field Service. They also had some
ECO/FCO's to the read/write module for preamp current IIRC.
Been a long time since I worked on them.
The ones without the glue problem worked pretty well... They really got
screwed by the glue being swapped by the vendor. The new glue was close in
properties -- but reliquified at a lower temperature causing major problems
when the original glue was discontinued and became unavailable.
Bill
On 11/5/06, Jay West <jwest at classiccmp.org> wrote:
Jules wrote....
I certainly would have thought that it's
worth your while to make up as
many good units as possible out of the bits, unless you know that the
failures aren't fixable already. As I recall the drive's on-board diags
are pretty good (as are the manuals - I'm pretty sure there were
comprehensive test procedures in there)
Yes, I'm aware of the diags. I have
read the manuals quite some time ago
and
saw the cute built-in "console port" and such.
I had written...
> but they are clearly dead
To which Jules responded.
How do you know?
Because the collector on this list who gave me all the RA81's said they
were
tested and dead, and he put the "Bad HDA" tags on the front. But you're
right I shouldn't take his word for it. I should retest them all.
Jay
6 Nov
6 Nov
3:04 a.m.
Jay West wrote:
I had written...
I suppose the 'right' thing to do would be to at least run the diags and offer
the units up on here along with diag results. Seems a shame to kill a unit for
the sake of what might be an easy repair to you or someone else.
But... time is not infinite and all that, plus these aren't exactly easy
critters to ship if someone *did* want one! :-)
(I'm facing the same problem with some of my stuff - masses of untested parts,
potentially the chance of building up a few working systems which then would
be useful to people, but no time to actually do it. I suppose it's one of
those things that plagues a lot of us...)
cheers
Jules
--
If you've ever wondered how you get triangles from a cow
You need buttermilk and cheese, and an equilateral chainsaw
> but they are clearly dead
To which Jules responded.
How do you know?
Because the collector on this list who gave me all the RA81's said they
were tested and dead, and he put the "Bad HDA" tags on the front. But
you're right I shouldn't take his word for it. I should retest them all.
10:01 a.m.
Jules wrote...
I suppose the 'right' thing to do would be to
at least run the diags
Yup, I was planning on running diags and piecing together as
many working
units as I could. However, given the previous testing done on them I
strongly suspect many have bad HDA's, and as such would be better as parts
donors to a drive that has a working HDA. My impression is that donor HDA's
are not generally available, and thus few people ran these drives, and thus
few people would want any parts.
But... time is not infinite and all that,
Exactly. I'm under a time crunch and need to stop talking about it and get
some gear out of here. Best way I can see to do that is put together the
systems I want from all the parts, keep a spare set, then dispose of the
remaining bits (here, ebay, trash, etc.). I'd love to stop and play with the
systems as they come up, but time currently doesn't allow. In other words,
if the wife sees me putting together systems and the trash pile growing -
good. If she sees me sitting there running one... ;)
(I'm facing the same problem with some of my stuff
- masses of untested
parts, potentially the chance of building up a few working systems which
then would be useful to people, but no time to actually do it. I suppose
it's one of those things that plagues a lot of us...)
Which is why I posted
here about it. One - to let people know of my
predicament and see if MAYBE someone wants to take a few off my hands and/or
help with testing. Two - to get advice from others who have them already as
to what parts are most in need and should be saved for my own (and perhaps
others) use as spares.
Jay
3 Nov
3 Nov
6:30 a.m.
On 11/3/06, Jay West <jwest at classiccmp.org> wrote:
Lastly, are the casings for the RA81's mostly steel, or aluminum? I'm
pondering putting them in the van and taking to a scrap metal dealer. I
wouldn't do this, but they are clearly dead, HDA's not likely to appear,
no
one wants them, and I need the space.
I once saw some opened RAXX disks. I think the enclosure is made of
aluminum. There might be some poeple who are both tube amp and vintage
computer hobbists, that want to use the enclosure to make some cool looking
tube amp.
vax, 9000
Jay West
8:22 a.m.
Hey All,
On 11/3/06, Jay West <jwest at classiccmp.org> wrote:
[RA81s with bad HDAs]
Since I don't know anything about RA81's yet
(have never used them or opened
one up), and because I do intend to keep one or two of the drives running (a
few don't say "bad hda" on them), can someone tell me what parts I should
scavange off the dead ones that are worth keeping as spares? I know the
obvious like the light bulbs and drive select plugs, but what about
components on the inside that "those in the know" would advise I not just
pitch with the drives?
I seem to remember, many moons ago, of a story where a couple of
physisists used the servo assemblies from the head actuators to make a
magnetically susported table. The table was automatically adjusted for
any vibration and to keep it level. I don't remember if they used the
head assembly servos from an RA81 or a different type of DEC drive.
Has anyone else heard of this story and can remember if it was RA81
drives or not?
Thanks.
Simon
--
------------------------------------------------------------------------
"Well, an engineer is not concerned with the truth; that is left to
philosophers and theologians: the prime concern of an engineer is
the utility of the final product."
Lectures on the Electrical Properties of Materials, L.Solymar, D.Walsh
9:55 a.m.
Pics of guts: <http://www.carrott.org/vax/bigdisk.html>
--
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
<http://www.xmission.com/~legalize/book/download/index.html>
11:44 a.m.
In article <454B8EC2.7000200 at srv.net>,
Kevin Handy <kth at srv.net> writes:
Richard wrote:
Not my drive, just the results of my google image search.
I suspect its a Euro version.
--
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
<http://www.xmission.com/~legalize/book/download/index.html>
Pics of guts:
<http://www.carrott.org/vax/bigdisk.html>
Frequent mentions of 240 volts in article:
Either you have a much different drive than I ever used,
[...] 
8:29 a.m.
"Jay West" wrote:
Since I don't know anything about RA81's yet (have never used them or opened
one up), and because I do intend to keep one or two of the drives running (a
few don't say "bad hda" on them), can someone tell me what parts I should
scavange off the dead ones that are worth keeping as spares?
I'm sure other with more knowledge will have better suggestions, but I
would grab (in order of priority)
- all the belts which drive the HDA
- one spare motor + clutch assembly
- one set of the 3 logic boards
- one "back power supply" box
- a couple of sets of the plastic buttons (they break) and one of the
pcb's behind it + the ribbon cable
- the red SDI cables from the controller board to the back and the back
plate if it's there
the ra81's have internal diags and you could try and power them up and
see if the power supply & boards are functioning. hard to say, but might
be fun. you can test it with the led's and switches on the main board.
Good, "in rev" HDA's are hard to come by. I have at least one RA81 with
no HDA. I could use a good HDA. And if you do remove an HDA and want
it keep it be sure and read about not putting weight on the bottom
spindle - you want to flip the HDA over and set it on it's top.
Apparently you can damage the HDA by setting it down on the spindle
(please correct me if I've got that wrong).
-brad
1:54 p.m.
Since I don't know anything about RA81's yet
(have never used them or opened
one up), and because I do intend to keep one or two of the drives running (a
few don't say "bad hda" on them), can someone tell me what parts I should
scavange off the dead ones that are worth keeping as spares? I know the
I would keep all the PCBs. No I've not suddenly started approving of
board-swapping, but it's the best way to keep any/all custom chips, ROMs,
etc.
I'd probably keep a few spindle motors and transformers. And any sensors
on the outside of the HDA.
Then I'd take an HDA apart as non-destructively as possible That is,
undoing bolts, not cracking castings. And pbotograph it as I went. It
would be an intenersing set of pictures for the wrb, I think [1].
[1] THere are too few web pages showing the internals of classic
computers IMHO. I'd much rather see the PCBs and layout than the outer
case.
I'd probably keep that dismantled HDA (put back toghter, but obviosuly
not useable) for interest, showing to fellow hackers, etc
Lastly, are the casings for the RA81's mostly
steel, or aluminum? I'm
At least for the Rx80, the main chassis is plated steel.
-tony
6621
days inactive
6624
days old
12 comments
9 participants
participants (9)
-
ard＠p850ug1.demon.co.uk -
brad＠heeltoe.com -
fryers＠gmail.com -
julesrichardsonuk＠yahoo.co.uk -
jwest＠classiccmp.org -
kth＠srv.net -
legalize＠xmission.com -
pechter＠gmail.com -
vax9000＠gmail.com