11 Sep
2012
11 Sep
'12
10:35 a.m.
I was the one that was able to snag the LA-36 DECWriter II that Corey
Anderson had rescued from being scrapped.
Thanks, Corey, I really appreciate it! I had a great time chatting
about the "old days" with Corey when I visited his home to pick up the
LA-36.
I intend to use this as the console terminal for my PDP 11/34 system.
It's a lot more appropriate than the Heathkit H19 currently serving that
purpose.
I got the LA-36 home on Sunday, but didn't have time to do much with it
until yesterday.
I did a basic cleaning -- getting rid of dust and cobwebs. In general
the terminal was in pretty good shape, and despite some dust and spider
leftovers, it was quite clean inside.
One of the first things I noticed was that the main controller board
looked different than I expected, and on closer inspection, I saw that
it wasn't a DEC board. It said "SELANAR CORP." and "GRAPHICS II"
in
silkscreen on the board.
There are sockets for eight 2708 EPROMs, of which 6 are filled (I was
worried that some were missing because of the empty sockets), with round
stickers over the windows that say "SELANAR". There are three sockets
for some kind of RAM (haven't identified it yet), of which only one
socket is filled. There appear to be two processors, one made by
Western Digital, and another made by Fairchild. Both appear to have
onboard EPROM, as they have windows on them that are painted over with a
thick black paint.
I checked all of the fuses, and they were good. I unplugged everything
from the control board (keyboard connector, printhead
drive, carriage
drive stepper, pin-feed drive stepper), serial connector, and a
couple
of power connectors, and powered up the power supply, and found that all
of the voltages were good, with minimum ripple. I did a close visual on
the controller board, and it looked good...no debris or signs of
overheating/blown components. I also checked out the solenoid and
stepper driver board, and it also looked good.
I wiped down the carriage rail to remove dust and grime, and then oiled
it lightly. The carriage moved smoothly in both directions, but the
ribbon advance mechanism seemed a bit gummed up, which I figured I could
address later, since the ribbon is all dried out anyway.
I plugged all of the connectors back in, and put some paper in it, then
used a variac to slowly power it up.
It didn't appear to like being slowly powered up, as the steppers got
all wonky - but, I didn't get any smoke, so I quickly ramped the power
back down, plugged the DECWriter directly into mains, and powered it up
with the power switch.
The carriage went left until it hit the stop with a bang...and sat there
with the stepper humming for a nervous 3/4 or so second, then the
carriage moved to the right a bit, and things got quiet (other than the
hum of the power supply). I set the machine to local mode, and hit a
key, and the pins hit the ribbon/paper, and the printhead moved to the
next print location. After a familiar delay, the printhead moved to the
right to allow the character (which was invisible because of the bad
ribbon) to be seen. I typed all of the characters on the keyboard, and
everything seems to work -- linefeed, carriage return, backspace, space,
repeat, bell(^G), etc. So, the unit appears to be in good shape, though
I don't know if the characters print correctly until I can find a ribbon
for it.
I'm quite happy that it seems to be generally alive.
Now, on to the point of my posting:
Does anyone know anything about Selanar's Graphics II board for the
LA-36? BitSavers doesn't have anything that I could find. Google nets
old ads and product announcements in trade rags of the day (1982-ish).
Selanar also made graphics engine boards for VT100's, Televideo 950's,
and various other printing and display terminals. One advertisement I
saw showed an LA-36 that had a pretty printout of a Spirograph-like
drawing.
I would love to find some documentation on how the graphics work. I
found some information relating to FORTRAN libraries that provided
routines for "MOVE", "DRAW", and various other graphics primitives,
but
no real documentation. I'd love to find an operator's guide or a
programming guide to figure out how to make the graphics work.
I plan on pulling the ROMs and dumping them, and passing them to
BitSavers.
Anyone out there have any information on this thing that they could
share?
I'm going to do some more cleanup, test the serial port to see if it
works, and track down a ribbon for it (I have a lot of calculator
ribbons that I may put onto the spools for the DECWriter just as a
temporary measure). The serial cable has had the connector cut off, so
I'll have to figure out the pinout and put a connector on the end.
Plenty of stuff to keep me busy. There is a DB-25F connector on the
Selanar board that isn't plugged into anything. I'm wondering what it
might be for, so I may hook a terminal up to it and see if I can get any
kind of response from it. Hopefully someone out there will have some
docs for this thing that can eliminate the mysteries of this relic.
Thanks,
Rick Bensene
11 Sep
11 Sep
5:41 p.m.
New subject: Selenar Graphics II (Was: DECWriter II LA36 being given away)
In article <B9639BAE3F34504E83FEEDD71D4AFB463D4595 at mail.bensene.com>,
"Rick Bensene" <rickb at bensene.com> writes:
Does anyone know anything about Selanar's Graphics
II board for the
LA-36?
I knew that Selanar made a graphics board for the VT-100; I didn't
know they made one for LA-36. That's exciting! I found these hits
via Google books:
"Plug-In Converts the DECwriter to Plotter", InfoWorld, November 21, 1979
<http://books.google.com/books?id=LD4EAAAAMBAJ&lpg=PA19&ots=PbU5HsoFz4&dq=selanar%20graphics%20decwriter&pg=PA19#v=onepage&q=selanar%20graphics%20decwriter&f=false>
"Board Adds Features to Decwriter LA35, LA36", Computerworld, December 4, 1978
<http://books.google.com/books?id=omXPM3l72p8C&lpg=PA37&ots=zebVuGqvVB&dq=selanar%20graphics%20decwriter&pg=PA37#v=onepage&q=selanar%20graphics%20decwriter&f=false>
Resolution is 1320x792, 4 fonts with APL standard. I'm guessing your
EPROM slots are either firmware, font definitions, or both. The RAM
slots look to be for the "1,000 character buffer" that allowed
communication speeds up to 1200 baud.
"Other standard features include EIA RS-232, 20mA current loop and TTL
interfaces." Perhaps your other DB25F connector is the TTL interface.
I have a Selanar board for the VT100, but I don't have one for the
LA36, although I knew there were aftermarket boards for LA36 that
provided faster printing and graphics features.
[...] I'd love to find an operator's guide or
a
programming guide to figure out how to make the graphics work.
It's entirely possible the graphics commands are compatible with
Tektronix 4010/4014. I would cobble together a little BASIC program
(or whatever) that outputs some Tek4010 vector drawing commands and
see what happens.
Google books excerpted an entry from BYTE, 1982, that appears to give
the escape codes for the graphics commands. The excerpt reveals:
pg. 176:
^L Form feed
^N APL character set Selects 2nd character set
(factory set with APL)
^O Normal character set Selects normal character set
ESC 5 Print entire character set Test mode
ESC 7 Upside-down print mode Rotates characters 180 degrees
ESC 8 Sideways I print mode Rotates characters 90 degrees
ESC 9 Sideways II print mode Rotates characters 270 degrees
ESC 0 Double width characters Prints double width characters
ESC A Boldface characters Prints each character in boldface
ESC C Special reset Returns DECwriter to normal
configuration
ESC F Power-up reset Resets ???, character styles,
tabs, and top of form
(also occurs at power-up)
ESC H Down 1/4 line
ESC J Set bar mode In graphics mode, prints all
seven dots instead of one at a time
ESC N 3rd character set Selects 3rd character set
(factory set with math and
greek symbols)
ESC P 4th character set Selects 4th character set
as defined in programmable memory
By carefully crafting more google book searches, I was able to extract
more of the table above. The issue in question is March, 1982, Volume
8, Number 3 pg. 172 "Graphics II by Selanar".
<http://malus.exotica.org.uk/~buzz/byte/pdf/BYTE%20Vol%2007-03%201982-03%20Printers.pdf>
<ftp://helpedia.com/pub/archive/temp/Byte/BYTE%20Vol%2007-03%201982-03%20Printers.pdf>
LA36 ribbons are still fairly easy to obtain, so you should have no
problem getting a "real" ribbon for it. Also, I think you can have
the old ribbons re-inked.
--
"The Direct3D Graphics Pipeline" free book
<http://tinyurl.com/d3d-pipeline>
The Computer Graphics Museum <http://computergraphicsmuseum.org>
The Terminals Wiki <http://terminals.classiccmp.org>
Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>
8:23 p.m.
New subject: Selenar Graphics II (Was: DECWriter II LA36 being given away)
Having downloaded the BYTE in question, a more complete version of
Table 1 from the article is as follows:
^L Form feed
^N APL character set Selects 2nd character set
(factory set with APL)
^O Normal character set Selects normal character set
ESC 5 Print entire character set Test mode
ESC 7 Upside-down print mode Rotates characters 180 degrees
ESC 8 Sideways I print mode Rotates characters 90 degrees
ESC 9 Sideways II print mode Rotates characters 270 degrees
ESC 0 Double width characters Prints double width characters
ESC A Boldface characters Prints each character in boldface
ESC B Enter graphics mode
ESC C Special reset Returns DECwriter to normal
configuration, exits graphics mode
ESC F Power-up reset Resets all modes, character styles,
tabs, and top of form
ESC G Up 1/4 line
ESC H Down 1/4 line
ESC J Set bar mode In graphics mode, prints all
seven dots instead of one at a time
ESC N 3rd character set Selects 3rd character set
(factory set with math and
greek symbols)
ESC P 4th character set Selects 4th character set
as defined in programmable memory
ESC Q Load-memory character set Defines 4th character set to be
loaded into programmable memory
Once in graphics mode, the Selanar doesn't use Tek401x command
sequences as I guessed, but uses ASCII digits and the following
command characters:
0-9 Build number in accumulator
( X1 := X2, Y1 := Y2, clear accumulator
, X2 := accumulator, clear accumulator
. Y2 := accumulator, clear accumulator
) Draw line from (X1, Y1) to (X2, Y2)
] Move to (X1, Y1)
--
"The Direct3D Graphics Pipeline" free book
<http://tinyurl.com/d3d-pipeline>
The Computer Graphics Museum <http://computergraphicsmuseum.org>
The Terminals Wiki <http://terminals.classiccmp.org>
Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>
9:28 p.m.
I was tasked with doing something with one of those for the University
of Minnesota Computer Center (and of course had forgotten all about it
until you mentioned it. I don't even remember what we used it for,
though I have a vague recollection of doing super- and sub-scripting for
formatted documents on it (or was that a Diablo? It's been quite a
while.). I think I tried drawing stuff with it, maybe as a hardcopy for
contemporary terak graphics, or something. It might have improved the
performance of the LA36, perhaps by adding 1200bps and lots of
buffering. These neurons are old and tired. The odds that I have
anything in my archive that used this printer are infinitesimal (but
nonzero).
--
Jeff Woolsey {woolsey,jlw}(a){jlw,jxh}.com first.last at gmail.com
Spum bad keming.
Nature abhors a straight antenna, a clean lens, and unused storage capacity.
"Delete! Delete! OK!" -Dr. Bronner on disk space management
"Card sorting, Joel." -me, re Solitaire
12 Sep
12 Sep
1:24 a.m.
When I joined DEC in 1975 my first job was selling LA36's, VT52's and
VT100's to OEM's
A foreign board in the back is no surprise. I could sell the whole LA36,
System less logic board or just the print mechanics.
Even in the UK my minimum order quantity was 500 units per year.
Some things to watch for on the LA36
1. If you get a light or missing dot do not assume it?s one of the print
head solenoids or a driver transistor. The synthetic agate through which the
wires run to the print point were prone to get gummed up. Take the head off
and wash it in alcohol. Look out for the agate falling out when you wash it.
2. Steer clear of using Teletype ribbons. They have china clay in the ink
and are as abrasive as hell.
3. Worn or frayed ribbons are prone to shed fibers which
4. Make sure whatever ribbon you use has the end of ribbon reversing eyelet
present and make sure the reversing is working.
5. Fan fold paper can be 14 7/8" or 15 1/4"
6. Multipart paper is OK but it?s the pack thickness and not the number of
sheets that count.
Regards
?
Rod Smallwood
?
?
-----Original Message-----
From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org]
On Behalf Of Rick Bensene
Sent: 11 September 2012 18:36
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Selenar Graphics II (Was: DECWriter II LA36 being given away)
I was the one that was able to snag the LA-36 DECWriter II that Corey
Anderson had rescued from being scrapped.
Thanks, Corey, I really appreciate it! I had a great time chatting
about the "old days" with Corey when I visited his home to pick up the
LA-36.
I intend to use this as the console terminal for my PDP 11/34 system.
It's a lot more appropriate than the Heathkit H19 currently serving that
purpose.
I got the LA-36 home on Sunday, but didn't have time to do much with it
until yesterday.
I did a basic cleaning -- getting rid of dust and cobwebs. In general
the terminal was in pretty good shape, and despite some dust and spider
leftovers, it was quite clean inside.
One of the first things I noticed was that the main controller board
looked different than I expected, and on closer inspection, I saw that
it wasn't a DEC board. It said "SELANAR CORP." and "GRAPHICS II"
in
silkscreen on the board.
There are sockets for eight 2708 EPROMs, of which 6 are filled (I was
worried that some were missing because of the empty sockets), with round
stickers over the windows that say "SELANAR". There are three sockets
for some kind of RAM (haven't identified it yet), of which only one
socket is filled. There appear to be two processors, one made by
Western Digital, and another made by Fairchild. Both appear to have
onboard EPROM, as they have windows on them that are painted over with a
thick black paint.
I checked all of the fuses, and they were good. I unplugged everything
from the control board (keyboard connector, printhead
drive, carriage
drive stepper, pin-feed drive stepper), serial connector, and a
couple
of power connectors, and powered up the power supply, and found that all
of the voltages were good, with minimum ripple. I did a close visual on
the controller board, and it looked good...no debris or signs of
overheating/blown components. I also checked out the solenoid and
stepper driver board, and it also looked good.
I wiped down the carriage rail to remove dust and grime, and then oiled
it lightly. The carriage moved smoothly in both directions, but the
ribbon advance mechanism seemed a bit gummed up, which I figured I could
address later, since the ribbon is all dried out anyway.
I plugged all of the connectors back in, and put some paper in it, then
used a variac to slowly power it up.
It didn't appear to like being slowly powered up, as the steppers got
all wonky - but, I didn't get any smoke, so I quickly ramped the power
back down, plugged the DECWriter directly into mains, and powered it up
with the power switch.
The carriage went left until it hit the stop with a bang...and sat there
with the stepper humming for a nervous 3/4 or so second, then the
carriage moved to the right a bit, and things got quiet (other than the
hum of the power supply). I set the machine to local mode, and hit a
key, and the pins hit the ribbon/paper, and the printhead moved to the
next print location. After a familiar delay, the printhead moved to the
right to allow the character (which was invisible because of the bad
ribbon) to be seen. I typed all of the characters on the keyboard, and
everything seems to work -- linefeed, carriage return, backspace, space,
repeat, bell(^G), etc. So, the unit appears to be in good shape, though
I don't know if the characters print correctly until I can find a ribbon
for it.
I'm quite happy that it seems to be generally alive.
Now, on to the point of my posting:
Does anyone know anything about Selanar's Graphics II board for the
LA-36? BitSavers doesn't have anything that I could find. Google nets
old ads and product announcements in trade rags of the day (1982-ish).
Selanar also made graphics engine boards for VT100's, Televideo 950's,
and various other printing and display terminals. One advertisement I
saw showed an LA-36 that had a pretty printout of a Spirograph-like
drawing.
I would love to find some documentation on how the graphics work. I
found some information relating to FORTRAN libraries that provided
routines for "MOVE", "DRAW", and various other graphics primitives,
but
no real documentation. I'd love to find an operator's guide or a
programming guide to figure out how to make the graphics work.
I plan on pulling the ROMs and dumping them, and passing them to
BitSavers.
Anyone out there have any information on this thing that they could
share?
I'm going to do some more cleanup, test the serial port to see if it
works, and track down a ribbon for it (I have a lot of calculator
ribbons that I may put onto the spools for the DECWriter just as a
temporary measure). The serial cable has had the connector cut off, so
I'll have to figure out the pinout and put a connector on the end.
Plenty of stuff to keep me busy. There is a DB-25F connector on the
Selanar board that isn't plugged into anything. I'm wondering what it
might be for, so I may hook a terminal up to it and see if I can get any
kind of response from it. Hopefully someone out there will have some
docs for this thing that can eliminate the mysteries of this relic.
Thanks,
Rick Bensene
12:28 p.m.
Some things to watch for on the LA36
1. If you get a light or missing dot do not assume it's one of the print
head solenoids or a driver transistor. The synthetic agate through which the
wires run to the print point were prone to get gummed up. Take the head off
and wash it in alcohol. Look out for the agate falling out when you wash it.
Do not dismantle th printhead (The same applies to the LA100 head, and
many Epson heads, and doubtless others). Dismantling it is easy.
Reassembling it is next to impossible. The print pins (wires) were
originally mcuh longer, they were fed through the guides, the head was
put toghter, the wirees were then cut/groudn to length. if you take the
head apart, you will never get the wries to stay through all the guides
(due to the return springs) whill you puti together. Oh, the wires are
some metal that is quite brittle and which will not take solder. Don't ask...
The only heads I would attemtp to dismantle i nthe field and there ones
in the Sanders variopritners, the Model 43 Teletype one (for which there
is a dismantling procedure given i nthe service manual) and the old Epson
ones (TX80, also used in Commoder 2022, etc) where the front section
cotnaing the print pins is a complete unit that comes off with a retainer
plate to keep the wires in position. Don;t dismantle that but you can
take the solenoid section apart.
-tony
13 Sep
13 Sep
3:56 a.m.
Quite so ..
Although I did not say do not take it apart I quite agree.
Heads would always be replaced never repaired.
I do remember a field service engineer gently moving the print wires with a
pair of needle nosed pliers where they were visible underneath. I was
surprised how far they stuck out in front of the final guide.
Regards
?
Rod Smallwood
?
?
-----Original Message-----
From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org]
On Behalf Of Tony Duell
Sent: 12 September 2012 20:29
To: cctalk at classiccmp.org
Subject: Re: Selenar Graphics II (Was: DECWriter II LA36 being given away)
Some things to watch for on the LA36
1. If you get a light or missing dot do not assume it's one of the print
head solenoids or a driver transistor. The synthetic agate through which
the
wires run to the print point were prone to get gummed
up. Take the head
off
and wash it in alcohol. Look out for the agate falling
out when you wash
it.
Do not dismantle th printhead (The same applies to the LA100 head, and
many Epson heads, and doubtless others). Dismantling it is easy.
Reassembling it is next to impossible. The print pins (wires) were
originally mcuh longer, they were fed through the guides, the head was
put toghter, the wirees were then cut/groudn to length. if you take the
head apart, you will never get the wries to stay through all the guides
(due to the return springs) whill you puti together. Oh, the wires are
some metal that is quite brittle and which will not take solder. Don't
ask...
The only heads I would attemtp to dismantle i nthe field and there ones
in the Sanders variopritners, the Model 43 Teletype one (for which there
is a dismantling procedure given i nthe service manual) and the old Epson
ones (TX80, also used in Commoder 2022, etc) where the front section
cotnaing the print pins is a complete unit that comes off with a retainer
plate to keep the wires in position. Don;t dismantle that but you can
take the solenoid section apart.
-tony
11:23 a.m.
Quite so ..
Although I did not say do not take it apart I quite agree.
Heads would always be replaced never repaired.
Howe3ver, people here often do repairs that no field servoid would
contemplate.A motor would not be reound in the field, but I've
done it several times (in an LA36, an HP9125 plotter, etc, etc, etc).
Simialry, many of us (OK, me at least) do component-level repair on
machines that were nromalyl field-repaired by board-swapping.
Hence my warning. These dot matrix printheads are not at all easy to
reassembel without a new set of p[rinmt wires. I would avoid taking them
apart!
I do remember a field service engineer gently moving
the print wires with a
pair of needle nosed pliers where they were visible underneath. I was
surprised how far they stuck out in front of the final guide.
A gopd adjustable bench supply ('good' meaning to goes down to 0V, which
a lot of modern ones don't) is useful here. Connect it between common and
one of the print solenoid wires (with the head unplugged from the driver
board, of course) and slowly turn up the volts. The pin will come
forwards, it foesn't take much votlage to do it either. The tpyically
stick out 2 or 3 mm when fully driven.
-tony
14 Sep
14 Sep
12:22 a.m.
Not a bad way to test but do remember that the head solenoids were designed
for pulse operation so do not power more one at a time and don't leave the
power on for too long.
Regards
?
Rod Smallwood
?
?
-----Original Message-----
From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org]
On Behalf Of Tony Duell
Sent: 13 September 2012 19:24
To: cctalk at classiccmp.org
Subject: Re: Selenar Graphics II (Was: DECWriter II LA36 being given away)
Quite so ..
Although I did not say do not take it apart I quite agree.
Heads would always be replaced never repaired.
Howe3ver, people here often do repairs that no field servoid would
contemplate.A motor would not be reound in the field, but I've
done it several times (in an LA36, an HP9125 plotter, etc, etc, etc).
Simialry, many of us (OK, me at least) do component-level repair on
machines that were nromalyl field-repaired by board-swapping.
Hence my warning. These dot matrix printheads are not at all easy to
reassembel without a new set of p[rinmt wires. I would avoid taking them
apart!
I do remember a field service engineer gently moving
the print wires with
a
pair of needle nosed pliers where they were visible
underneath. I was
surprised how far they stuck out in front of the final guide.
A gopd adjustable bench supply ('good' meaning to goes down to 0V, which
a lot of modern ones don't) is useful here. Connect it between common and
one of the print solenoid wires (with the head unplugged from the driver
board, of course) and slowly turn up the volts. The pin will come
forwards, it foesn't take much votlage to do it either. The tpyically
stick out 2 or 3 mm when fully driven.
-tony
12:17 p.m.
Not a bad way to test but do remember that the head solenoids were designed
for pulse operation so do not power more one at a time and don't leave the
power on for too long.
You will find you need quite a low voltaeg to get the pins to extend.
Typoca;;y these ehads are runm from 24V or 36V supply rails i nthe
printer, but a 5V bench supply will normally operate them,. The actch is,
of course, the operate a lot more slowly (due to the inductace of the
coils) on the lower votlage. That's why the higher voltage is sued in
operation.
YEs, they will over heat if left on too long. But you can certainly test
a head in this way, and clean the exposed part of the pin without
damaging it.,
Of coruse you are not going to leave the head unattended when doign
this. You are likely to be hand-holding the head. You will notice if
it's getting hot.
Incidentally, if you ever have to reasseble the X-axis drive suystme of
the HP7245 printer/plotter, it helps to be able to lock the drive pulley
whenyou are widning the drive cabel round it. I have found that
energising one winding of the drive stepper motor (again, only 5 or 6
volts) will do this, and the motor doesn't get hot in the time it takes
ot put the thing together.
-tony
16 Sep
16 Sep
1:32 a.m.
Yes I totally agree with your comments
Sadly although I sold thousands of LA36's in the UK I don?t have one.
I do have an LA75 and an LA50.
Obviously LA36's, LA120's and LA180's are much larger animals and tend to be
scrapped do to the storage space they need. That reminds me of a story. When
I joined DEC I got the inevitable list of cars to choose from. In those days
they were mostly Ford Cortinas. I duly chose one and added 'Estate' to the
description.
About a week later my new car arrived but not an estate version. So I asked
the fleet manager what was the problem. She said an estate was not on the
list. OK say's I, bring the car over to Ealing.
She pulls up into the car park to see another Sales person and I carrying an
LA36 in to the car park. We invited her to load the LA36 into the vehicle
provided.
She went a very bright pink, got into the car and drove off. When I arrived
next day the keys for the top Ford estate model were waiting in reception.
Regards
?
Rod Smallwood
?
?
-----Original Message-----
From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org]
On Behalf Of Tony Duell
Sent: 14 September 2012 20:17
To: cctalk at classiccmp.org
Subject: Re: Selenar Graphics II (Was: DECWriter II LA36 being given away)
Not a bad way to test but do remember that the head solenoids were
designed
for pulse operation so do not power more one at a time
and don't leave the
power on for too long.
You will find you need quite a low voltaeg to get the pins to extend.
Typoca;;y these ehads are runm from 24V or 36V supply rails i nthe
printer, but a 5V bench supply will normally operate them,. The actch is,
of course, the operate a lot more slowly (due to the inductace of the
coils) on the lower votlage. That's why the higher voltage is sued in
operation.
YEs, they will over heat if left on too long. But you can certainly test
a head in this way, and clean the exposed part of the pin without
damaging it.,
Of coruse you are not going to leave the head unattended when doign
this. You are likely to be hand-holding the head. You will notice if
it's getting hot.
Incidentally, if you ever have to reasseble the X-axis drive suystme of
the HP7245 printer/plotter, it helps to be able to lock the drive pulley
whenyou are widning the drive cabel round it. I have found that
energising one winding of the drive stepper motor (again, only 5 or 6
volts) will do this, and the motor doesn't get hot in the time it takes
ot put the thing together.
-tony
10:29 a.m.
Sadly although I sold thousands of LA36's in the
UK I don't have one.
I do have an LA75 and an LA50.
I think i have an LA50 somewhere. I certainly heve a couple of LA100s [1]
and an LA324 [2]
[1[ I do like the 'nodding printhead' in this unit. The printhead is
mouted o na solenoid mechanism that moves the business end by havle a dot
pitch vertically. That means you can get the equivelent of an 18 pin
prinehed in 2 passes.
[2] This is a more recent 24 pin unit with 3 microprocessors inside. I
beleive it can taek a colour ribbon, but Iv'e never got one for it. This
is also the only thing I own with an MMJ connector (!).
Obviously LA36's, LA120's and LA180's are much larger animals and tend to be
The LA110 is a lot smalelr than the LA36. The LA36 has a lot of
electroncis in the stand, so it can't be turned int oa tabletop unit. The
LA100 is.
-tony
11:58 p.m.
If I remember correctly the LA100 was somewhat typewriter like.
It may have been called a LetterwriterII and the keyboardless version
Letterprinter II
Regards
?
?
-----Original Message-----
From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org]
On Behalf Of Tony Duell
Sent: 16 September 2012 18:29
To: cctalk at classiccmp.org
Subject: Re: Selenar Graphics II (Was: DECWriter II LA36 being given away)
Sadly although I sold thousands of LA36's in the
UK I don't have one.
I do have an LA75 and an LA50.
I think i have an LA50 somewhere. I certainly heve a couple of LA100s [1]
and an LA324 [2]
[1[ I do like the 'nodding printhead' in this unit. The printhead is
mouted o na solenoid mechanism that moves the business end by havle a dot
pitch vertically. That means you can get the equivelent of an 18 pin
prinehed in 2 passes.
[2] This is a more recent 24 pin unit with 3 microprocessors inside. I
beleive it can taek a colour ribbon, but Iv'e never got one for it. This
is also the only thing I own with an MMJ connector (!).
Obviously LA36's, LA120's and LA180's are much larger animals and tend to
be
The LA110 is a lot smalelr than the LA36. The LA36 has a lot of
electroncis in the stand, so it can't be turned int oa tabletop unit. The
LA100 is.
-tony
4479
days inactive
4485
days old
12 comments
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