[GreenKeys] KSR33 fixed! Problem and Solution notes

[Chris Elmquist]

Another issue that can cause misprinting and also incorrect characters
being transmitted is a failure of the answer back mechanism.

I had an M33 that would not print correctly locally or send correctly
remotely.  I traced this down to a broken tab on one of the answer back
drum contact springs.  These tabs are all plastic and pretty brittle.

When one lets go, the spring can no longer hold the contact open and
that single bit will then be stuck on and "OR'd" with the rest of bits
in each character you transmit.   The end result is that you do not
transmit the same code that you typed.   Depending on which spring let
go, you might change "A" into "B" or "A" into "C", etc.

As always, Wayne's excellent advice about visual inspection would reveal
this little gotcha too.  It's just that you have to look REALLY close
to see that one of those tiny springs is hanging loose or missing.

Chris NØJCF

On Tuesday (08/25/2015 at 01:28PM -0500), PJ Bennett wrote:
> Thanks Wayne, you’ve been a great help and very generous!  Good point on the visual inspection.  A big part of the debugging though was figuring out what to look for (which you helped with greatly).
> 
>  
> 
> For others in the group, I’ve attached a picture highlighting one of my issues.  When I did the “clothes pin” test I accidentally popped off the small spring when removing the spacer tool (plastic part in my case).  I should have done this per Wayne’s instructions and I wouldn’t have had the problem, but in case anyone else has ample power to their magnet and it’s still not moving, check the spring.  When it pops off it just sits on top of the tab and looks like it’s connected.
> 
>  
> 
> Hope this helps,
> 
>  
> 
> PJ
> 
>  
> 
> _____________________________________
> 
> PJ Bennett, BSEE
> 
> 918.704.7055 |  <mailto:pj at pjbennett.com> pj at pjbennett.com | pjbennett.com
> 
> 
> 
>  
> 
> From: teletypeparts at comcast.net [mailto:teletypeparts at comcast.net] 
> Sent: Tuesday, August 25, 2015 1:09 PM
> To: PJ Bennett <pj at pjbennett.com>
> Cc: GREENKEYS BULLETIN BOARD <greenkeys at mailman.qth.net>
> Subject: Re: [GreenKeys] KSR33 fixed! Problem and Solution notes
> 
>  
> 
> PJ,
> 
>  
> 
> Good explanation on GK.  Once again, most issues fixed by VISUAL INSPECTION.  All but one I guess.  Here is the pic of the 1/3 clothespin in the armature if any GK 33 guys want to use it sometime.  It goes in hugging the side frame and closes the armature manually to test the printer stopping all 3 clutches mechanically.  Doesn't do the distributor clutch. 
> 
>  
> 
> Your vinyl hammers and green resistor went out today.  If you don't need the green resistor, could you please return it.  They rarely fail, but the ones I have seem to have a quality control issue.  If you still need it then use it of course. 
> 
>  
> 
> Wayne
> 
>  
> 
> 
> 





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-- 
Chris Elmquist