[GreenKeys] Weird 33 keyboard problem

[Charles]

Thanks to both Don and Wayne for helpful suggestions. As you can
see below, I did find the problem and it was a keyboard contact
wire out of position. The reader is in need of repair and I have
an old punch requiring cleanup before I install it. So it's really
a KSR at the moment ;)
The printer was printing exactly what it was told to do, BTW.

So this afternoon, I was happily playing Adventure on my PDP-8/A
(to which this 33 is connected) when after a couple of hundred
lines of text, there was an awful "scrawk" noise and everything
locked up =8^0

I took the cover off yet *again* and found the belt in pretty sad
shape, the distributor immobile, and a lever obviously out of
position jamming the roller on the distributor clutch mechanism.
The E-clip on the end of the roller was missing, too (20 cents at
my local farm store). I took out the distributor shaft assembly
and cleaned and lubed the clutch and the other moving parts in
that area. The problem appears to have arisen because either I had
set too much endplay in the shaft, or more likely something had
loosened, allowing the distributor shaft to move to the right far
enough so that particular lever had slid off the rotating "disc"
and jammed solidly beneath the roller. After reassembly it's
working once more (fortunately I had a spare belt).

Oh, the "joys" of old hardware!

-Charles


>One of the last updates to the 33 keyboard was to put complete  
>plastic casing around the contacts.
>I am pleased you were able to find the problem.
>Don
>
>On 13 Sep 2007, at 12:22 PM, Charles wrote:
>
>Found it... one of the right-hand shift contact wires was
>dislocated from its base contact!
>
>Nothing binding though. I'd have expected more trouble with keys
>not "doing" anything, or sticking, not necessarily just outputting
>the wrong code...
>
>I am pretty fed up working on both my 33s too! The surest way to
>get it to screw up is to put the cover back on ;)