On 2019-12-15 9:35 p.m., Jon Elson via cctalk wrote:
On 12/15/2019 01:19 AM, Dave Wade via cctalk wrote:
I wonder if there is any interest here...
-----Original Message-----
From: [email protected]
<[email protected]> On Behalf Of John Lawson
Sent: 10 December 2019 17:41
To: [email protected]
Subject: [GreenKeys] DURA Selectric ASR terminals free
Greetings List!
I have a couple of "DURA" Selectric ASR terminals. I also have some
limited documentation on them. Neither of them work as far as I know.
I tried to run the one in the pic when I first got it, but it's
jammed - so on the shelf it went.
They appear to be an 8-level code, dunno if ASCII, EBCDIC, or what.
The punched tape is EIA, I think. There are diode matrices to convert
to the internal Selectric code of rotation and tilt of the ball. I
had one of these hooked to a CP/M system back around 1980, I used it
exclusively as a printer.
I could likely dig out some code that sent the data to them. A quick
look did not turn up the interface.
I seem to recall it had some pretty weird logic levels, PNP Germanium
transistors, etc.
It is possible to trip too many solenoids at one time and command the
rotate or tilt summing levers to exceed the
limits of the ball. That will break bands on the carriage. I had no
problem getting replacement parts when I had that
happen on mine. Not too sure Selectric parts are available anymore.
Jon
These are joining the ever-expanding list of "Projects Never to be
Completed", so if anyone is interested, lemme know.
They are free, you pay shipping, they are about 50 pounds each and
will require some thoughtful packing.
Local pickup is happily offered, and I could possibly be bribed into
delivering them within a day's drive of Carson City (weather
permitting).
Cheers
John KB6SCO
Carson City
Speaking as a person that has been up to my elbows in many Selectric
terminals it is not possible to select too many of the selection magnets
at the same time if you pick all of the selection magnet at the same
time you will get -5 rotate and 0 tilt. Picking any of the positive
selection magnets pulls the associated latch off the bail and cancels
the positive motion of that latch. Picking the -5 magnet releases the -5
bail to get -5 motion which can be then combined with +1 +2 +3 +4 +5
rotate to get -4 -3 -2 -1 and 0 rotate respectively. Now if you trip
the shift magnet during a print cycle bad things will happen bad things
will happen, a down shift while the ball is detented will usually result
in the the rotate tape jumping off the shift arm and if you are lucky
the ball will get released and it will wind up the slack and the rotate
tape will get caught on the dust cover and you can carefully rotate
the ball while keeping tension on the rotate tape and ease it back onto
the shift arm. An upshift while detented will probably break the rotate
tape.
The ones I used to work on the most where banking terminals with up to 3
selectrics on a control unit so if we where replacing something like a
rotate tape the bank would not let us turn off the control unit and
inside the typers there where unprotected 48V terminal block for the
magnets, if you touched one with the rotate tape you where threading in
it would burn the tape in half and to add insult blow the 48V fuse.
Paul.
