28 Apr
2005
28 Apr
'05
7:27 p.m.
I am looking for troubleshooting tips for a 33 teletype.
I'm testing in local mode and am getting incorrect characters
on (almost) every keypress. The characters will change even
with repeated pressings of the same key. I am pretty sure the
keyboard is outputting the correct codes.
I wiped down the distributor surface (it was pretty grimy) and no change.
I tried adjusting the range finder but could never find a point where the
characters were consistent.
Is it possible to disconnect the motor drive belt and rotate the shaft
manually to get a closer look at what is happening mechanically?
It's very hard to see what is going on in the selector area with the
shaft spinning so fast.
By the way, my drive belt is somewhat loose. Is there still a source
for these? Or maybe an adjustment for tightening?
Thanks,
Bill
28 Apr
28 Apr
7:24 p.m.
By the way, my drive belt is somewhat loose. Is there
still a source
for these? Or maybe an adjustment for tightening?
Thanks,
Bill
Try Dataterm in Woeburn, Massachusetts. I have a nice ASR-33 teletype
that I bought from them last year. They also used to service them and
they might have spare parts.
Ashley
7:28 p.m.
From: "Bill Kotaska" <bkotaska at charter.net>
Sent: Thursday, April 28, 2005 9:27 PM
I am looking for troubleshooting tips for a 33
teletype.
I'm testing in local mode and am getting incorrect characters
on (almost) every keypress. The characters will change even
with repeated pressings of the same key. I am pretty sure the
keyboard is outputting the correct codes.
I wiped down the distributor surface (it was pretty grimy) and no change.
I tried adjusting the range finder but could never find a point where the
characters were consistent.
Is it possible to disconnect the motor drive belt and rotate the shaft
manually to get a closer look at what is happening mechanically?
It's very hard to see what is going on in the selector area with the
shaft spinning so fast.
By the way, my drive belt is somewhat loose. Is there still a source
for these? Or maybe an adjustment for tightening?
Thanks,
Bill
I am a member of another list related just to teletypes (greenkeys).
You may want to join it and ask for advice there:
http://www.rtty.com/greenkeys.htm
The 33 is just one model supported on the list.
Randy
www.s100-manuals.com
29 Apr
29 Apr
3:18 p.m.
I am looking for troubleshooting tips for a 33 teletype.
I'm testing in local mode and am getting incorrect characters=20
on (almost) every keypress. The characters will change even=20
with repeated pressings of the same key. I am pretty sure the=20
keyboard is outputting the correct codes.
I presume you know that the keyboard outputs parallel ASCII, which is
serialised by the distributor.
In 'line' mode, full duplex. the transmitter (keyboard + distributor)
appears to be a normally closed switch between the 2 Tx loop terminals.
It should be very easy to turn that into something approximating to RS232
using a couple of 9V batteries and a 1k (or so) resistor :
+-------------------+
| |
------- 9V /
--- \ 1k
| /
| \
| |
| +------ TxD on Rs232 port
| |
+-------------------)------ Signal Ground on RS232 port
| |
| o
------- 9V Tty TX terminals
--- o
| |
+-------------------+
This would at least tell you which side of the Teletype was malfunctioning.
[...]
Is it possible to disconnect the motor drive belt and
rotate the shaft=20
manually to get a closer look at what is happening mechanically?
I find it easier to electrically stop the motor and turn the machine over
using the motor cooling fan (remove the air deflector plate if you find
it helps). Some machines have a motor fuse on a bracket at the rear left
corner of the typing unit, behined the receiving magnet. If you have
that, just take the fues out. Otherwise, you can disconnect the motor
leads at the starting relay (if used), or remvoe the pins from the Molex
plug, or something like that.
It's very hard to see what is going on in the
selector area with the
shaft spinning so fast.
By the way, my drive belt is somewhat loose. Is there still a source
for these? Or maybe an adjustment for tightening?
I probably so still have a spare belt, but I am the wrong side of the Pond...
Yes there's an adjustment. Loosen the 4 motor mouting screws (2 on each
stap that holds the motor down) and rotate the motor housing to tension
the belt.
-tony
11:16 p.m.
I used to service these machines for Western Union years ago.
*********** REPLY SEPARATOR ***********
On 28-Apr-05 at 21:27 Bill Kotaska wrote:
I am looking for troubleshooting tips for a 33
teletype.
I'm testing in local mode and am getting incorrect characters
on (almost) every keypress. The characters will change even
with repeated pressings of the same key. I am pretty sure the
keyboard is outputting the correct codes.
Never assume. One problem area we had was that the stiff spring-contact wires that the
keyboard uses to set up the code can get dirty or oxidized where they contact the common
busbar. Check this. Also, check the wiring between the keyboard and the distributor
plate.
I wiped down the distributor surface (it was pretty
grimy) and no change.
I tried adjusting the range finder but could never find a point where the
characters were consistent.
Did you change the carbon brushes in the distributor rotor? That was another problem area
for us.
Is it possible to disconnect the motor drive belt and
rotate the shaft
manually to get a closer look at what is happening mechanically?
It's very hard to see what is going on in the selector area with the
shaft spinning so fast.
Absolutely it's possible. That's how we troubleshot a lot of problems.
I would, however, strongly recommend that you try to get a service manual for this beast.
It came in a three-volume set.
Happy tweaking.
-=-=-=-=-=-=-=-=-=-=-=-
Bruce Lane, Owner & Head Hardware Heavy,
Blue Feather Technologies -- http://www.bluefeathertech.com
kyrrin (at) bluefeathertech do/t c=o=m
"If Salvador Dali had owned a computer, would it have been equipped with surreal
ports?"
30 Apr
30 Apr
2:43 p.m.
I'm testing
in local mode and am getting incorrect characters
on (almost) every keypress. The characters will change even
with repeated pressings of the same key. I am pretty sure the
keyboard is outputting the correct codes.
Never assume. One problem area we had was that the
stiff spring-contact
That is a more general point. Never assume anything -- far too much time
has been wasted assuming something is working correctly when it could be
trivially tested!
That was the point of my idea to test the trasnmitter side separately. We
need to know which area of the machine has problems, then narrow down on
the faulty part.
More generally still, if something is safety-related, never assume
anything. If you ever get me working on a machine with you, you will find
I never trust you've turned off the power/unplugged it. I will check. If
you feel insulted by that, I frankly don't care. And if I say I've turned
something off, I expect you to check. I won't be insulted, I know I can
easily make mistakes [1]
[1] Like most hackers [2], I love a good practical joke, but I don't regard
claiming to have isolated something whan I've not done so as a joke.
Potential death situations are not funny.
[2] I am not claiming to be a hacker. I know I am nowhere near good enough.
-tony
6957
days inactive
6958
days old
5 comments
5 participants
participants (5)
-
ard＠p850ug1.demon.co.uk -
bkotaska＠charter.net -
cctalk＠randy482.com -
kyrrin＠bluefeathertech.com -
wacarder＠usit.net