[GreenKeys] Model 28 - Top edges of letters barely visible

[gfmurphy at earthlink.net]

Hi Jim:

The hammer spring adjustment is only for situations where you are using
multi-part forms.  For single ply paper, leave the adjustment on the lowest
number.

Check out these items on your printer:
Look at the 153810 ribbon guide on the typebox carrier.  It should be clean 
and free of any kind of gunky build-up.  The ribbon must be free to move up
and down inside of the ribbon carrier.  If the ribbon can't move up when the
print hammer is about to hit, the tops of the characters will not print.

Check out the right and left side ribbon feed mechanisms.  There were 2 versions
of the ribbon feed mechanism.  The early version had 152630 ribbon spool shafts
and 150327 ribbon rollers.  The later version used 154332 ribbon spool shafts 
and 154333 ribbon rollers.  The later design parts were available as the 154334
Mod Kit to convert early design units to late design units.  What's the difference
between the early design parts and the late design parts?  The late design parts
lifted the ribbon a bit higher so that the tops of the characters would print.
The 154332 ribbon spool shaft had a thicker base than the early design 152630
ribbon spool shaft.  This difference is not obvious if you look at the parts book.
The 150327 early design ribbon rollers had lips on them that were equal sized.  
The 154333 late design ribbon rollers had a much thicker lip at one end and a very
small lip (or no lip at all) at the other end.  So, if your 153810 ribbon guide is 
clean and you have the late design parts in place everything should look good.  It 
should look good if the parts are installed correctly.  It is possible to install 
the 154333 ribbon rollers upside down and that's what will happen if you follow
the images in the Teletype manual.  The early design 150327 ribbon rollers could 
not be installed incorrectly.

I have a Model 28 typing unit parts manual - BSP 573-115-800TC - that is dated
April of 1975.  This is a relatively new manual in the Model 28 evolution.  Yet,
it continues the error of showing the 154333 ribbon roller with the thick end in
the up position.  The thick end of the roller MUST be in the down position.  If
all of the parts are clean and are installed correctly, then you should not be
seeing non-printing at the tops of the characters.  The only other thing that you
might check is the tautness of the ribbon.  If the ribbon is sagging, it will not
be able to rise up to the right position. 

Good luck with your project.

Jerry Murphy




-----Original Message-----
>From: N4BE_Jim via GreenKeys <greenkeys at mailman.qth.net>
>Sent: Jun 24, 2014 8:13 PM
>To: "greenkeys at mailman.qth.net" <greenkeys at mailman.qth.net>
>Subject: [GreenKeys] Model 28 - Top edges of letters barely visible
>
>I have a 28 KSR I am refurbishing, and its printing on a loop, but the top 
half of all characters is faded or not visible.  New ribbon. Cleaned the type 
box.  I've increased the hammer spring tension adjustment, it gave me a bit 
more of the tops but mostly just made the bottoms darker.  I slow motioned the 
machine by turning the motor by hand and the hammer strikes perfectly horizontally 
but it appears to be striking toward the tops of the plungers.  Is there some kind 
of vertical alignment adjustment?
>
>I have read about platens hardening with age.  Hopefully that's not the problem.
>
>Thanks,
>Jim
>