[GreenKeys] Troubleshooting 35 ASR Printing

[Ken Wiebe]

Thanks! I got the sticky bits to mostly work by finding a lever that seemed like it should move but wasn't. I gently nudged it. It still sticks a little sometimes but for the most part I can now press any key and actually see printed what I pressed. Sometimes it takes a couple of presses of the key to get the right character. Woo-hoo!

What are thoughts on cleaning a typing unit?

There is a guy on YouTube (CuriousMarc) who has a video series chronicling a Model 19 restoration. In one of the videos he submerges the typing unit in a Simple Green bath:

https://www.youtube.com/watch?v=0SgIMJPnYPk

Is this recommended?

Basically I'd like to proceed now to ungunking the mechanisms of this 35. Can it be done without complete disassembly? Or maybe only partial disassembly?

-Ken


On Sat, May 25, 2019, at 05:38, Nick England wrote:
> With the motor off, press a key that should cause the sticky bits to mark. According to your diagnosis, those keyboard code bars will be released but won’t move left like they should. 
> So try to move them by hand using a screwdriver to gently push. Maybe you have gunked up grease so they can’t move easily. Maybe they have missing springs so they aren’t getting pulled left. 
> 
> If the code bars won’t move with a bit of pressure, then they haven’t been released or something is bent or blocking them. You may need to remove the typing unit and then remove the keyboard base from the cabinet. so you can turn it on its side to see what’s happening on the bottom. Watch some code bars that are operating properly to compare to the problem area. 
> 
> If you take remove the typing unit, you can turn the keyboard drive shaft by hand to go through a keyboard cycle. If the typing unit is still in place, you can just turn the motor. 
> 
> Note. When cycling by hand the keyboard shaft clutch won’t release at the end of a cycle (because you aren’t going fast enough) but that won’t matter for manual testing. 
> 
> Written from often faulty memory. I’ll probably have to issue multiple corrections when I wake up and look at a machine!
> 
> Or maybe I am misreading and your keyboard code bars are working ok and the problem is in the printer. My experience there is that the culprit is often gunk in the levers and push bars that connect selector to code bar. 
> 
>  I wish we had instant teleportation so we could look at it together. People who have been to teletype school must have had a great advantage over those of us trying to learn in isolation. 
> 
> The teletype is a wonderful piece of mechanical digital logic. Sticky bits are caused by obstruction (equivalent to a grounded signal line in electrical logic) or a missing spring (like no pull-up resistor). 
> 
> Good luck and Have fun solving the puzzle!
> Cheers 
> Nick
> 
> 
> On Fri, May 24, 2019 at 10:20 PM Ken Wiebe <me at networkguy.com> wrote:
>> __
>> I read the doc on the typing unit and also some helpful replies to an earlier thread, in an attempt to chase down why I don't get expected characters to print.
>> 
>> Based on an analysis of the characters printed vs key pressed, I believe I have the issue "traced" to code levels 1 and 5 not marking.
>> 
>> I think most, if not all, printing anomalies I'm seeing can be explained by 1 & 5 never marking. There does seem to be some intermittent shift key anomaly (it doesn't work right away sometimes), but other than that I think if I can fix 1 & 5 it will make a huge difference. Perhaps the shift key issue is a problem with level 7 (?)
>> 
>> I said "traced" above because obviously more tracing is necessary. I observed the code bar shift levers in operation and I attempted to follow in the doc the description of operation, but I'm not sure where to look next to isolate further why the levers responsible for levels 1 & 5 would fail to mark.
>> 
>> Any hints what to do next?
>> 
>> Ken
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> Nick England K4NYW
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