[GreenKeys] Kleinschmidt TT-4C update #3

[Greg Arnoldussen]

I have progressed quite a bit since my last update, though the Olympic coverage over the last two weeks stole my attention somewhat!  I managed to get both TTYs talking to each other without too much problem.  It didn't work to begin with but I received advice from both Steve Garrison and Richard Youl to get the motors in sync, which I did, and no problems then.  Being the novice I was not using the tuning fork correctly and worked out that holding the fork close to the eye, rather than close to the motor, was much much easier.  TTY-247 soon had an issue with the platen being locked in the FIGS position but I finally narrowed it down to a lever catch (with spring) on the LHS of the platen, not exactly sure what the issue was or how I fixed it...that's one for the mystery box.  A little oil and it fired up & down no problem.  However, during comms with the TTY-176, it decided to stop, and well, it remains stopped.  I could not invoke it to start
 again via a BREAK signal from it's sister TTY-176.  As was the case when I first began work on these beasts the motors would not run (and I had no loop supply at the time) and that involved fiddling with the relays, but so far I have had no luck.  To be honest I have left that project for another day as I received Eric Volpe's demod board in the post last week.  I suppose I can count myself lucky that I have two identical machines!  So over to TTY-176....

With the board out the package (and beautifully soldered together, thanks Eric) I attempted to hook it up via cheap and nasty ear bud headphones and a new 9V battery.  My limited knowledge began shining through again when I could not work out how to get a solid frequency lock on the board (red LED), and I could not work out how to hook up two wires into the board when I only had one to play with, but I worked out that the tiny wires from one ear bud contained a bunch of small blue wires and one larger copper coloured wire (the blue wires were the shielding I presume, or earth wires).  And when I mean small, I mean small - my vision is not great at the best of times and a magnifying glass is next on the list.  So having sorted that out and wiring it into the board, I placed the jack into the line out of the laptop, started the ITTY feed program, and the red light came on strong with the blue LED flickering in sync with the code.

Now the issue which I am hoping I can get some ideas from.  Upon firing up the TTY it began typing everything absolutely verbatim for several minutes, but then began printing rubbish in amongst legible words, that included line feeds and bells ad-hoc throughout!  I have a Youtube video of the problem here:  http://youtu.be/oS7ozcdq48s  It does not look good - notice how it seems to want to "catch up" or fall behind, and in the process prints rubbish.  But, when it prints properly (and I am sorry I did not get video of it working well) it really seems to be OK.

Things I have tried:
- Adjusting the motor speed (seems to work best running slightly slow).
- Adjusting the range finder.
- Adjusting the line resistance.
- Adjusting the volume on the laptop.

Eric suggesting fiddling with the frequency screw on the board - to be honest I think it could be more of a machine issue than anything, but it is something I should try nonetheless (but not having a scope I was worried I might not be able to get it back again).  I say this because when I turn the motor off and leave the loop supply going the relay continues to click away nicely, so it seems the demod board is working well.

So, the only immediate thing that comes to mind is that as the TTY warms up something seems to be playing up.  Fine adjustment of the motor does not help.  As it does warm up there begins a noise somewhere in the gears that sounds a bit like a groan, not constant, but comes in and out with every revolution - it is most noticable when the carriage is at the extreme right (which, by the way, was always there, it just only seems to become apparent throughout the whole span of the carriage as it warms up).  It is not really the sort of noise that would prompt me to get worried, it just seems to be rubbing.  If you listen to the first two seconds of the Youtube video you will catch the noise I am speaking of.

The printing problem may be nothing to do with the noise, but so far I have been having trouble physically seeing any trouble.

Greg

Wangaratta, Australia.
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