Bringing up a KSR-33 Teletype

[Creideiki]

Hello again peoples.

I've recently come across a KSR-33 teletype that my university was discarding (I've switched schools by the by, I'm at Brock University now, not the University of Waterloo). The teletype doesn't have a dialer or anything in it, so it was most definitely used either as a dumb terminal for a mini or something.

Cosmetically, the upper portions of the teletype are quite perfect - just a few scuffs and some dirt and grime that is older then I am - the base though does show a bit of rust, so that'll need some attention.

Smoke testing the teletype (not my idea as a first test, but that was done by the electronics shop), shows that it powers up fine, and looks to be functional in most regards. However there is a major issue - though I think I know the solution to that - namely, the carriage stays in one position and is repeatedly striking the print head against the paper. (It does not respond to any character input, nor does it print anything, as there is no ink ribbon.)

The solution to that problem I believe is that several of the cables that extend from the back of the teletype are not connected to anything, and there is a large box (branded by a company called UTEC, or some such) that has what appears to be the sockets for those plugs.

Here's an illustration of the wiring:

The unknown plugs-that-do-something-which-I-don't-know-what-that-is match up to three sockets on the UTEC box-thingy. So I'll assume the cables plug into the UTEC box-thing. I am also assuming that the teletype is converted for RS-232 signalling (as evidenced by the DB25M connector.

The major problem is that I think the UTEC box is the RS232 converter, and should be controlling what the TTY is doing, and that without the plugs inserted the teletype becomes a non-responsive paperweight.


Here's a link to a (blurry) photo of my KSR-33 on the floor of my dorm room: > Click me! <



Unfortunately, I won't be able to do anything with it until Sunday evening or Monday, as I'm home for the weekend. (Also, I'd like to know if I should try plugging the various cables into the UTEC box-thingy, or whether that would be unwise and could damage the teleprinter.)


So, any helpful hints/suggestions? And what all have you people done with your KSR-33s? (Other then the blindingly obvious uses of course.)

 

[Creideiki]

Pardon the double post, but I've returned to my dorm room, and I have taken a few more pictures of the teletype to illustrate the items described in the above post.


Firstly, here's a nice, clear picture of it from the front:

One can clearly see the TTY was branded by a company called LEIGH, which I've never heard of before. One can also see that the face plate for the teletype is still intact. One thing I find odd though is the mismatched key colouration.


Here now is a shot of the system from the back:

The UTEC box is on the right, and is hard wired into the teletype. The mystery cable that splits is draped across it. And the data cable is on the left (showing the connector that mysteriously splits from it.


Here's a quick shot of the mechanism:

To my untrained eyes it looks good, save that there is no more rubber on the hammer.


Now, here's a picture of the UTEC box and it's connectors:

Each connector matches with the cable connectors.


Here are the info plate and logo plate of the UTEC box if any one can help me ID what it is:

Here's a picture of the data cable at the split point:

I wonder if the little blue cable that is cut (and that I just noticed) is important.


Here's a picture of the three mystery connectors:

The mystery connector on the signal cable is a male connector, with a 3x5 pin matrix; with only three pins. The mystery connectors on the second cable are female 3x5 pin matrices; one with only two connectors and one with only one.


And here's the DB25M connector:

That's all I've got that's new, and I hope all of that is useful/interesting to you. And any one who has any information I welcome the help.

 

[saundby]

I would open the UTEC box and the KSR-33 to see where the wires connect, and what's in the box will tell you what it does. The Molex connectors look like power connectors, perhaps they supply RS-232 compatible power? I'd open the box and see what parts are inside.

 

[Creideiki]

I've tried to open the UTEC box, actually, the screws seem to be exceedingly tight; though that could just be because of the fact all I have is a set of precision screw drivers.

I made a short, kind of low quality video which can be found here (~17MB; .MOV format), showing the issues (though I made two flubs, the second time I say "local" I mean to say "line" and also, plugging the connector with "13" on the side into J3 and the one with "14" on the side into "J4" (and the other connector into J2) it stops doing that repeating thing.

Also, I've never opened a KSR-33 before, I assume the proper way to open it is remove the three thumb screws at the back and lift off the cover?

 

[nige the hippy]

2 points, I got an asr33 fairly recently. it had had a mechanical refurb before being put into storage about 30 years ago.
I had 2 issues with it.
firstly the carriage didn't seem to want to respond to anything
and secondly (when I did get the carriage to move) the keyboard went into "continuous" mode

The first problem was mostly solved by removing, cleaning out & re-greasing the "turret" which drives the carriage belt, which was full of dried-up grease and was seriously stiff. There were still occasional problems with it, and that was due to one of the drive "pawls" that pushes it along not quite going back far enoogh to catch the next ratchet tooth. there is an adjustment "somewhere" for that, I'll have to check the manual again.

The keyboard problem was down to the nylon "toggles" on the code bars, which push on the code switches. These are returned by light spring pressure and need to swivel freely, I think the nylon had swelled slightly in damp storage, although there was more dried up "grease" around there too. I actually dishwashered the keyboard, thoroughly dried it in a warm place for a few days, then dripped some silicone oil onto the toggle shafts. Which part of the process worked I'm not sure, but it did.

Beware of opening up the keyboard, there are a lot of things that go Sproing, and you'll end up with a SR-33!!!

 

[Creideiki]

Keyboard wise, the teletype is happy, and as far as I can tell, it is probably going to stay that way. Also, could you point me in the direction of the correct manual for the Teletype? (I ask because I don't want to make one of things that goes sproing, go sproing. And then have to fine the sproing that flew across the room.)

Here, by the way is a new video of the Teletype: > Click Me! <


I've also taken a few more pictures. Which are as follows:


Here are a pair of shots of the inside of the UTEC box (thank you university tech services for lending me a screwdriver).

From what it looks like, I have no idea what it does.


Here are two shots of the interface board on the inside of the teletype:

From what I can see, I assume there should be more connectors on the connector panel, correct? Also, the plug that is second from the left on the top row, is the origin of both the "mystery cable" and the DB25M cable. As well, the UTEC box's grey cable is the power connector plugged into the top of the block.


Here's a picture of the small card to the side and "behind" the connector block:

I include a picture of it, because the resistor at the top of the card gets extremely hot; as in it is hot enough I can feel the top of the case get warm. (And if I touch it it is very painfully hot.)


So, can anyone suggest a good mailing list/website devoted to the teletype? (I know one exists, I forgot the name of it though.) Cheers everyone. And I hope you all have a wonderful day.

 

[nige the hippy]

[FONT=Arial, Helvetica]From brian blackburn's site....[/FONT]http://bytecollector.com/asr_33.htm ....
[FONT=Arial, Helvetica]
Service manuals can be found at: www.pdp8.net/pdp8cgi/query_docs/query.pl?Search=teletype&stype=Partial+Wo
Also at Bitsavers: http://www.bitsavers.org/pdf/teletype/[/FONT]

 

[Creideiki]

Excellent, thank you very much for that.


Though I seem to have run into yet another issue; namely I powered up the TTY into Local mode -- proud nerd demonstrating the TTY to some lesser nerds -- and it started making an odd sort of sound, like something was off kilter, before I could shut it down; the fuse to the motor blew.

As a sort of last-ditch effort, I replaced the 3A slow-blow motor fuse (at least I think the motor fuse is a 3A slow-blow) with the 3A slow-blow fuse on the UTEC box; powering the system back on (yes, I know I shouldn't have done that), the system ran for a few seconds before the fuse burnt out once one. Which confirms my suspicion that something within has shorted out.

Does any one know what could be causing the motor's fuse to burn out? (And more also where I can find replacement fuses; right now I need two 3A slow-blow fuses. (Also, I'd like a spare 3A slow-blow and spare 1/2A slow-blow in case I have another issue.))


Thank you all for the help; the teletype is a really interesting machine, I just wish I knew more about it (and more on how to fix it).

So yeah, to chock up what's wrong with the teletype at present:

1. Carriage won't move.
2. Type hammer cushioning pad is non-existant.
3. Something in the power chain of the fuse near the motor has shorted.

 

[nige the hippy]

1) STOP!!!!!!!!


I was part way through watching the vid, and noticed point above. i.e. that the rubber pad is missing. The hammer will VERY QUICKLY destroy the type head. these are a bit harder to find than the rest of the teletype, mostly as a result of people ruining them! you need to buy/make a new rubber bit before going any further.

2) again from the vid, it certainly does sound like you have the same problem with yours as mine had, i.e. a gummed up carriage drive gear.

3) the "chunter-chunter-chunter...." when you put it online is pretty typical of a teletype online with no signal, it's just "marking"

4) the fact it works in "local" (it does "line feeds" on command) indicates it's probably going to be ok on line. (once the motor problem is sorted)

all for now....

 

[Creideiki]

THanks for the information.

I was leery of running it without the pad, and I was just doing it for the demo. My plan is basically the same as/similar to the plan on Mr. Blackburn's website - replace the non-existant hammer with a furniture cushioning pad. Though I'll probably end up using contact cement or something to hold it on, as I don't want it falling off and getting suck somewhere it shouldn't (and worse then that, completely destroying the type wheel). Until then however, outside of that video, I have a sponge sitting between the type hammer and the typewheel. That should provide some cushioning, eh?

In regards to two; I'll have to go have some "fun" trying to figure out how to do your fix then; as I really don't want to damage it (well damage it any further then what the problems it has now are).

In regards to three and four, so that's basically normal due to a floating connection? Is it normal though, when it is connected to the UTEC box though? (In otherwords, when it does nothing, and is unresponsive, but sounds like it's sending; is that just because the teletype doesn't have local echo? Better yet, was that even the right thing to do?)


Regarding the fuse situation, a good friend of mine (not in the same city as me right now due to my being away from home due to school), works at an electronics shop and has found replacement fuses. When I get a spare moment I'll have to bring my multimeter, as I need to find what's getting shorted (or whether the problem is being caused by something mechanical being jammed and making the fuse blow due to a stressed motor). Is there a simple (read: "won't break anything") way to check the mechanical aspects of the teletype, as I'm leery of touching the expanse of complex mechanical parts (something broken there wouldn't be as easy to fix as a fuse or two).

Also, due to the way the teletype's connections are, would I be correct in assuming it is setup for RS232 signalling as opposed to current loop? Also, correct me if I'm wrong, but the correct speed and bit pattern for the KSR-33 is: 110 bps, 7-M-1?

Thanks for all of the help. And any ideas as to what could be causing the motor issue would be helpful.

 

[nige the hippy]

it'll be a short one as i have a headache, but it looks like you remove the two screws in the metal clip over the left pulley to slip the belt off (the carriage will want to fly back so guide it back gently). you should then be able to easily rotate the pulley clockwise. If not, there may be a circlip holding the pulley on (tech bulletin 273 B (see bitsavers model 32 & 33 tech manual) sec 574-122-701 page 12 para 2.28 says "Shaft (remove bracket & retaining ring) ") then the pulley just pulls off (mine was worryingly firmly on) AFAIK the central screw head is for the shaft itself.
WD40 is fine for loosening the old grease, I moved mine out with a wet-wipe & a skewer, re-oil it, grease the ratchet teeth, and refit. Be careful not to damage the pawls as you slide the pulley back in.

As for the Motor, again it might be a case of dried up grease, giving it a harder time than it should have. Others may disagree, but I hit most of my machine with a bit of WD & light oil, just to get stuff moving smoothly again.

As for current loop vs RS232 I've only recently got the schematics, but I really am not sure it has an RS232 option. Your little box may have a converter in, it may just have bells & whistles driven from the auxillary contacts, I don't know. Mine's 20mA current loop, and a bit of wire just plugs into one of the square sockets on the back.

 

[nige the hippy]

p.s. The schematics are inpenetrable without a clear head, a clean table & a lot of coffee.

 

[Dwight Elvey]

Hello again peoples.


Smoke testing the teletype (not my idea as a first test, but that was done by the electronics shop), shows that it powers up fine, and looks to be functional in most regards. However there is a major issue - though I think I know the solution to that - namely, the carriage stays in one position and is repeatedly striking the print head against the paper. (It does not respond to any character input, nor does it print anything, as there is no ink ribbon.)

Hi
If the carriage doesn't move when you are in local mode, it is not and electrical problem.
Once a character is printed, there is a clutch that engages and cause the carriage to move.

The printer itself uses a current loop. There would need to be a current look to
RS-232 converter to run RS-232. It isn't clear from your pictures that it has one.
Dwight

 

[Dwight Elvey]

Hi
I forgot to mention, a hammer pad can be made from those stick-on feet you can get at the
hardware store. You need to remove the self sticky tape as it won't hold it and then
clean the hammer of any grease ( Brake-Clean from the auto parts store works ).
Then use some silicon rubber cement.
Did I say clean, I mean clean, even a finger will leave enough grease to make it
fail. You don't want that to happen in the middle of a long run.
Dwight

 

[Creideiki]

nige:

p.s. The schematics are inpenetrable without a clear head, a clean table & a lot of coffee.

I just took a look at the schematics and the technical manual. All I can say is: "Oh God."

Otherwise, I'd say the procedures sound pretty straightforward, though I'm less than mechanically inclined.


Dwight:
The carriage is not moving now, due to it being at the end of the line, so I'm not wholly sure if something isn't working there. First, I need to free the carriage so it will return; then I need to solve the motor/fuse issue. The print hammer issue will be solved when I get a chance to go to a Home Depot.

Though, I'm working on the assumption that the "UTEC box" is the RS232-current loop converter. Also, there is the fact that most times I've seen current loop, it's been a four-connection terminal strip, not a DB-25 connector (which I've seen either universally as a serial connector or parallel connector).

And any way the point as to what the communications interface with the rest of the world is, is moot until the mechanical issues are resolved.

 

[Creideiki]

Okay peoples, time for an update!

Firstly, the carriage has been returned; after getting in touch with the GreenKeys list the little latch/lever/thingy was discovered, released and my thumb crushed while the carriage returned.

I've still to clean and relubricate the machine. Though I've managed to do some cursory cleaning. I also found an elastic band that had fallen into the machine that looks to be at least ten years older then I am. Cleaning will probably be via the recommended-by-GreenKeys-methods. Lubrication will be... using the recommended oil; also I'm considering Marvel Mystery Oil as apparently it did wonders for an IBM Selectric II.

Also, and most annoyingly, I've yet to get my hands on fuses, so I can't test anything out yet. Also, I'm beginning to think the ESU for my teleprinter is current loop and not RS-232; so I'm going to be exceptionally careful if/when I get a chance to test it (I do hope it's RS-232 though; I don't want to build a current loop interface).

Also it was determined that my KSR-33 is quite a unique one, as no - documented - teletype keyboard arrangement matches mine (which is the subset of ASCII-1967 that is supported by Model 33 and Model 35 teletypes - that is upper case, symbols and control codes). Though this might be because my teletype is a LEIGH machine - meaning it was made in Canada, for use in Canada, to avoid import tariffs from the 'States.

Cheers everyone, and sorry for the long time between updates.

 

[billdeg]

Dwight
Thanks for the tip. I am going to replace the hammer pad of my TT's this weekend, at best they're a 3 on a scale of 1-10, one is missing entirely. The test TT I have been using has been good enough to get started, but now that I have it more or less running correctly I don't want to use it without new pads.
Bill

 

[nigwil]

The illustrious A Nabil suggested using a short length of plastic (nylon?) tube (clear plastic tubing you find at hardware stores for aquariums etc) fitted over the hammer (once you've removed the old rubber pad, the tube slides down the length of the hammer and the tube radius provides a pliant plastic impact point) - you want a selection of sizes and use one which is a really tight fit. The tight fit means it won't work loose and it provides a large (reliable) strike surface.