[GreenKeys] GreenKeys Digest, Vol 108, Issue 68

[John Nagle]

> Message: 3 Date: Sun, 27 Jan 2013 20:45:09 -0800 (PST) From: Paul
> Baggenstoss <baggens at yahoo.com> To: greenkeys at mailman.qth.net 
> Subject: [GreenKeys] Help with Model 15 Adjustment - bouncing
> carriage return Message-ID: 
> <1359348309.63143.YahooMailClassic at web161001.mail.bf1.yahoo.com> 
> Content-Type: text/plain; charset=us-ascii
> 
> Hi, I'm new to the group. I have a Model 15 (actually TG-7B)  that I
> have been using as a printer for all kinds of internet applications
> like weather and news. I have written an interface program and built
> a loop supply and terminal unit. It's a fantastic piece of
> machinery!
> 
> I wonder if anyone in the greenkeys group has some experience with a 
> bouncing carriage return.  My Model 15 seems in all other aspects to
> be in great shape. But recently I took the type bar carriage off to
> do some oiling and put it back on, and put a drop of oil on the
> carriage return dashpot piston. Ever since then, it prints without
> being able to find the start of the page. 
> 
> It seems to bounce when it hits the dashpot, but not always. Perhaps
> it is not a dashpot bounce, but a hard bounce - not sure.   It
> depends how far it travels - that is how long the last line was.  The
> dashpot seems to work if I hit it hard with my hand, it gives a
> satisfying hiss and absorbs the shock.
> 
> The manual talks about adjusting the dashpot vent screw so that there
> is "no bounce and minimum shock".  But this does not seem to be enough
> information.

     OK, if you have the dashpot adjusted reasonably, the problem is
probably with the carriage return clutch mechanism.  See Fig. 49 and
page 29 of Teletype Bulletin 138.
(http://www.aetherltd.com/public/model15manuals/138_Model15_Adj_Oct41.pdf)

     When the carriage return mechanism trips, the carriage return
clutch is unlocked and the carriage return spring pulls the carriage
back to the left.  When the left margin adjusting screw hits the
dashpot lever, the energy of the carriage return is dumped into the
dashpot, which brings the carriage to a stop.  The movement of the
carriage also resets the carriage return clutch via the reset bar.

     From the problem you are reporting, it sounds like the
carriage return clutch gets reset improperly.  Since you have a
machine that used to work, there's probably nothing serious wrong.

     As a check, space the carriage to the right and send a
single CR while watching the carriage return clutch fork and
carriage return clutch.  You should see the carriage return
clutch unlock, and it should relock immediately when the carriage
has returned, with the carriage at the left margin.  Watch
that enough times to make sure the clutch is relocking
properly.  If something was sticking in that area, though,
you'd probably get the first two or three characters on
the line typed on top of each other.  Are you seeing any
sign of that?  When the carriage does return properly, is
the spacing between the first two letters at the left correct?

    While there are lots of adjustments in that area, I'd suggest
not messing with the delicate ones at this point.  Make sure that
all the parts shown in Fig. 29 are clean, oiled, and not binding first.
Then, adjusting the left margin adjusting screw (instructions on
page 49) may be helpful.  If the left margin adjusting screw
is set incorrectly, the clutch will try to re-engage part-way
between two character positions, which will make it very
sensitive to any bounce in the carriage return.

		
				John Nagle