[GreenKeys] Modems, CCU's and Tractor feed issues

[Mike Douglas]

These are actually very "good" results for diagnosis. If you have read the punch pattern when typing "L" Ctrl-L and comma and verified they match their ASCII values, then we know your keyboard and distributor are working, and that also the print mechanism is working from data in, through the selector, through the blocking levers and to the codebars. (The punch, print head and function bars are all driven from the same codebars.)

This isolates the problem to the function bar mechanism for the form feed. However, a function activating when it shouldn't is much less common than a function failing to activate when it should. The latter is often fixed by lubrication of the codebar/function bar intersections and lubrication of the vertical pawls where they rub against guides and supports. 

I would still try lubrication first. Manually move the vertical pawls slightly up and down a bit as you apply the oil. Look for any obvious issue with the position of the form feed function bar, pawl position, springs on the function bar and the pawl, etc.

Let me know what you find!

Mike

On Dec 29, 2013, at 11:01 PM, "John Ball" <ball.of.john at gmail.com> wrote:

>> Tractor feed unit only works with sprocket fed paper -- there is not a
> friction feed option or >adjustment.
>> 
>> You're not seeing multiple line feeds, you're seeing a form-feed character
> activating the form feed >mechanism.  Form feed is 0x0C, which is Ctrl-L and
> also Ctrl-,
>> 
>> What is punching when you press comma? That will tell us if it's a
> keyboard, printer or function bar >problem.
> 
> Very well then on the paper. I'll figure out something with the carton of
> paper.
> 
> Huh, I never actually noticed that until now but you're right. The
> difference between a comma and a form feed is is the last three bits.
> Cranking out a piece of paper tape I can clearly see when I do a CTRL+L, a
> line feed and a comma so the keyboard is properly triggering, the punch is
> properly punching but the printer is missing those last three bits and
> interpreting it as a form feed. Just to write it off as a variable and
> because I did swap CCU's at least once I'll open the machine up again
> tomorrow and make sure that all the wiring is in order and I didn't bump the
> contact block or something.
> 
> -John
> 
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