[GreenKeys] M33 2^3 keyboard bit stuck

[Chris Elmquist]

On Tuesday (07/15/2008 at 10:30AM -0400), Teletypeparts at aol.com wrote:
> 
>    Lots of 33 kybd troubles can be found by visual inspection, lint or dirt on
>    a contact or a contact out of its guide.  Also check the answerback and tape
>    reader contacts to make sure none are crossed or loose etc.  Be careful not
>    to break anything.  Power off, of course.

And indeed after a bunch of looking (in the wrong place) I have found the
problem.  A tiny bit of plastic has broken on the clear acrylic base for
the answer back unit.  This little bit of plastic was the keeper for one
end of the spring that holds the ratchet against the answer back drum.
When the plastic gave way, the spring let go and fell down into the base
of the answer back assy.  The spring was then intermittantly shorting the
#4 T-lever on the answer back bus...  causing the 2^3 bit to mark when it
wasn't supposed to be.   Vibration caused the spring to be an intermittant
short and so explains why sometimes it would type correctly.  Geesh.

So, I am currently without the answer back feature-- which wasn't
programmed to anything anyway.  Unfortunately, with this problem, if you
do hit the "HERE IS" key, it will start the answer back drum in motion
which, without the spring and keeper, doesn't ever advance... and it
then tries to send the answer back message for forever.

I'll either have to find a replacement clear plastic base for the answer
back mechanism or disable the HERE IS key so that it isn't accidently
pushed.  Would have to take the whole machine apart each time to terminate
the answer back manually if this isn't fixed-- which would be a pain.

I guess 40+ year old clear acrylic doesn't have the strength they had
hoped for :-)

73, Chris N0JCF

-- 
Chris Elmquist
mailto:chrise at pobox.com