DECwriter Correspondent (LA12) mechanical issue...

[Josh Dersch]

Thanks a ton for going through the trouble on this, it's much appreciated.

I'll have to go through mine and see if that clip somehow ended up wedged
somewhere inside.  Otherwise, I guess it can't be too hard to build a
replacement.

Thanks again!
Josh


On Mon, Nov 10, 2014 at 7:39 AM, Simon Claessen <simski at dds.nl> wrote:

> hey there,
>
> Today I got some time to take a look at our correspondent and guess what,
> there should be a brass clip to hold the ball:
>
> https://hack42.nl/gallery/v/Museum/2014-11-10-693.jpg.html
>
> I could not take the clip off. wiggling it also moved the spring holding
> the print needle block.
>
> simon
>
>
> On 07-11-14 18:55, Josh Dersch wrote:
>
>> Hi all --
>>
>> Got myself a nice looking DECwriter Correspondent (AKA the LA12). It's
>> having a bit of trouble moving the carriage assembly and I can't find a
>> service manual for this thing.  (It's similar in some respects to the
>> DECwriter IV, but the mechanical parts appear to be fairly different.)
>>
>> The carriage assembly (print head, ribbon) is carried from one end of
>> the platen to the other via a cable attached to a servo motor on one end
>> and a pulley on the other; in the middle of this cable is a small metal
>> ball -- this ball is (as far as I can tell) meant to sit in a small
>> "cup" on the underside of the carriage and when the cable moves, the
>> ball pulls the carriage along.  I'm assuming this was done this way
>> since the Correspondent is meant to be portable, and allowing the
>> carriage to break free of the pulley mechanism would probably reduce
>> damage in the case of a sudden shock (like getting dropped.)
>>
>> So far so good -- unfortunately the vast majority of the time, the ball
>> leaves the carriage behind (especially on carriage return) and I can't
>> quite figure out what's out of tolerance -- the carriage appears to move
>> smoothly, nothing is bent out of shape or broken as far as I can tell,
>> and there's plenty of tension in the cable.  There's also not much to
>> adjust here so I'm kind of puzzled.
>>
>> I've put up a few pictures (and a short video demonstrating the problem)
>> with the print head/ribbon removed here:
>>
>> http://yahozna.dyndns.org/scratch/la12
>>
>> Anyone ever worked on one of these before?  Any ideas?
>>
>> Thanks as always,
>> Josh
>>
>>
> --
> Met vriendelijke Groet,
>
> Simon Claessen
> drukknop.nl
>