12 Nov
2002
12 Nov
'02
11:51 a.m.
Hi
I think you need to make this point clearer. When a
character
is punched, the same character is miss printed on the
platen?
This is how I read his original post.
Even using the REPT key to workaround the codebar
issue, I wasn't able to connect the carriage problem
conclusively to either a rotational or a vertical
problem. I think at this point I'm going to take the
carriage off again and try a more thorough
dismantle/clean/oil. Once I resolve the codebar issue
it will be easier to diagnose the carriage problem
with a clean mechanism.
This tells me it is something sticking in the linkage
that goes
between the code bars and the print head( or he has
it installed
wrong but that doesn't explain why it starts
working
with repeats ).
I would remove the print assembly and put it in some
solvent
while moving the levers. Then clean it off/dry it and
re-oil
it. You most likely have some dry oil that is
sluggish. Getting
oil into the right place will take a bit.
In the service( military ), we used to clean things
in a bath
of water and heavy detergent. This was done in an
ultrasonic
cleaner. We'd then rinse and bake it at about 150F
for a few
hours. Then Re-oil/grease, place on test bench and
fine adjust.
I suspect that a good dish washing liquid would work.
I remember using an arklone bath at a place I worked
years ago for cleaning circuit boards. Probably taken
a few years off my live expectancy breathing that
stuff in.
Basically, there are 3 possible problem areas :
1) The keyboard contacts are not closing correctly,
so the parallel data
output of the keyboard is incorrect.
2) The distributor disk (rear right of the typing
unit) is not correctly
serialising the data from the keyboard. Unlikely, but
possible.
3) The selector unit (rear left of the typing unit)
is malfunctioning,
and is not correclty responding the receiving magnet.
I can see the armature 'stutter' when I punch the
rubout key - by stutter, I mean that its movement
looks slightly different between keypresses. So I'm
inclined to think that the magnet is just responding
to what it is receiving which is incorrect. I cleaned
the distributor and reseated the brushes, readjusted
the brush holder to the alignment mark per the
adjustment procedure in the manual. So I'm back to
option 1) - the keyboard - as the source of the
problem. One thing I noticed last night was that the
keyboard cover is broken. There are four round tabs,
one at each corner, that fit into corresponding holes
on the end plates. These are broken, so the cover can
rock from side to side, pivoting on those center
projections. I wonder if that could cause some sort of
alignment problem within the keyboard ?
Thanks for the suggestions - I will get to it again
tonight and see what else I can find out. I hate the
idea of opening that keyboard up...
Dave
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