1 Jul
2013
1 Jul
'13
6:06 p.m.
At 11:05 -0500 6/29/13, bear wrote:
On Jun 28, 2013, at 2:10 PM, Chuck Guzis wrote:
Agreed with bear
Was the MO drive used on the NeXT cubes a
standard 650MB unit, or
was there something special about it? (e.g. sector size, encoding,
format, etc.)?
Not standard. The disks it uses are physically different from
"standard" ones. They are physically the same as early WORM disks
like the IBM 3363, though the media is different.
The drive NeXT used was made by Canon, and is the same as the Canon
DiskFile. However, you cannot use a Canon DiskFile to read NeXT
cartridges because the low level format is unique to the NeXT.
So if you want to read NeXT MOs, you need a NeXT. I have something like six units here, and none of them
work.
Including the one in my old cube I bought in '95 which worked when I
bought it, continued working for many years, was possibly the last
functioning NeXT MO in existence, and then just stopped while it was
in storage. I have the idea it could be coaxed back into life
somehow, but they are just about perfectly impossible to work on. If
anybody has had any success repairing these, I am unaware of it. One
guy says he's had success, but won't share information, so I am
choosing to believe he's a liar.
Almost agreed with bear. This might be me, and if so, I'm
flaky, but was telling the truth as I knew it. However the MO drive
failed again shortly thereafter, so I gave up in frustration and
never reported what I'd done. Apologies if I left anyone hanging!
I have only one MO drive, so my statistics aren't as good as
his, but yeah, I don't know of any that are still working.
Mine worked for years, then quit working (more retries, then
infinite retries). I took it out, got it far enough open to get a
q-tip full of isopropanol to the lens, and cleaned the dust off the
lens and the slide rails for the carriage. This was a fiddly process,
involving de-mating connectors, switching back and forth between top
and bottom of the drive, and figuring out how to prop the drive up
with some parts hinged open. However I would not call it "perfectly
impossible" - I did it, which probably means Tony could do it with
the drive running and one hand tucked safely into his hip pocket.
The unit ran normally when I got it back together, but for
not more than a few months. I have not taken a second pass at it.
Dust was likely an issue with my machine, because it had been
running with the fan in the normal orientation (air comes in the
drive and out the back of the machine). Good for cooling, but if
there's any dust at all in the environment, it ends up forming
bunnies on the MO lens.
The fan is mechanically symmetrical enough that it's easy to
invert it to run "backward". Air comes in the fan, dust cakes on the
rest of the machine, and nothing settles in the MO drive. Good for
optics - but bad for cooling. On my 68040 cube, this led to very
occasional crashes due to SCSI system faults. Since they happened
with at least two different hard drives which were otherwise
faultless, I deduce it was something to do with the motherboard,
which was then getting the warmest air in the box blowing across it.
(The crashes happened only during my morning "clean out old .nfs
files" cron job, which did a "find / -name ....". I diagnosed them by
distributed.net log file messages.)
I put my fan back like it was, and the SCSI crashes stopped.
Dust was clearly not the *only* issue with my machine. I
surmise that it was exacerbating whatever slow degradation process
affects all of them, and I bought myself a few extra months with the
cleaning.
More details available if anybody really needs them; I still
have the drive and the rest of the system, and can repeat the
disassembly I think, but not just immediately - I'm using the machine
at the moment.
FWIW, MO drive retry errors hang the machine - no monitor
mode or good way to continue. The low-level drivers for the MO
presumably operate at high priority, and block interrupts. SCSI
problems are not so bad, which is yet another reason that if you have
a NeXT running on a SCSI drive, switching to MO is a downgrade. They
were a technology with an extremely high "cool" factor but a limited
timespan of cost-effectiveness.
Good luck. You're going to need it. /@:
Agreed with bear on that one, too. I have not looked into
trying to find a replacement for the optical head. I suspect that
would be pretty tough.
At 18:23 -0500 6/30/13, <Dave R.> wrote:
I believe there are issues with dead electrolytic
capacitors among
other things. I suggest not powering on a drive without disassembling
and checking it first, though; I've heard of many cases where smoke
comes out of the drive when powered on.
Checking/replacing all the caps would take a while. The
drives have a lot of parts. However this is as good an explanation as
any I've heard. FWIW, there was no smoke from mine, then or yet (it's
still powered, in my cube).
Sorry for slow response, hope this is at least some useful.
--
- Mark 210-379-4635
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