26 Jan
2011
26 Jan
'11
5:34 p.m.
I read through the blog - if the motors start spinning
as you describe
(I envision you mean for a few seconds; please correct me if this is
wrong) _then_ the drive stops spinning, I doubt it's the capacitors.
If the motors _don't_ start moving when you put the drive online, then
that is one component to examine.
The motors start to spin up, accelerate for a few seconds and then
stop. A few years ago I fixed and RA81 that had the same symptoms by
replacing the starting capacitor.
RA81s were at one point, exceedingly susceptible to
HDA failure. ?I
don't recall the specific ECO levels, but some version after "E" used
a different glue than its predecessors leading to particulate
contamination leading to catastrophic failure. ?ISTR looking for "H2"
or "K2" drives after that disaster.
Two RA81s have tan colored HDAs, one has a black HDA. I think that the
black HDAs are the new design that doesn't crash so often.
RA81 drives have a DB25 inside. ?You can plug a
terminal in and run
on-board diagnostics and monitor operations. ?You can run with the lid
up or lid down (snaking a ribbon cable out of the drive). ?The molex
connector next to the data connector is to power a small hand-held LED
terminal (I saw one once, used with a high voltage chassis for
particle physics, but the terminal was the same).
Try plugging in a working VT220 and letting the drive tell you what it
thinks is going on. ?You might find that it's starting to spin up then
not liking what it sees and spinning down.
I forgot that I have a DEC Termiflex that plugs into the RA80/81 and
the TU81 diagnostic port. I will connect it to the drives this weekend
and see if I can get more details on the problem.
Oh... just a detail - you mention locked heads - you
_did_ pull the
cord to retension the drive belt, right? ?(for safe transport, the
RA81 has you locking the heads _and_ disengaging the motor from the
HDA by removing belt tension). ?If you didn't do this step, what I
think may happen is the onboard processor will start to spin the
motor, sense no rotation from the HDA, then spin the motor down and
emit a fault code. ?Maybe this is what you are seeing?
I saw the pull cable on the right side of the drive. I have used those
in the past to replace HDAs or motors. I will make sure that it was
not in a position to release tension on the drive.
Reading through your blog, I don't think you will have success with
booting 2.11BSD on your 11/44 with a TU81+ unless you have install
media that knows about that tape controller. ?The 2.9BSD tapes I have
require an "MS" device (older OSes might or might not require an
"MT"
device). ?Back in the day, there were several incompatible tape
controller types, with different boot ROMs, and your install media had
to match your controller and ROMs (or you had to toggle in the
bootstrap). ?You can install 2.11BSD using vtserver and a virtual tape
drive though. ?Also, if you do get real 2.11BSD install tapes, you'd
probably want to be looking for a TU80 and, IIRC, an M7454 controller
card.
-ethan
I looked at the 2.11BSD setup document and it says that the TU81+ is a
supported tape drive. There are two of those drives at RICM, but no
TU80. The M8739 KLESI-UA interface for the TU81+ doesn't seem to be
common or inexpensive. I think that the RCS/RI guys have one that I
could borrow for an installation. It might be simpler to just use
vtserver.
Thanks for all of the comments.
--
Michael Thompson