Fixing small plastic... things

Tony Duell ard at p850ug1.demon.co.uk
Tue Dec 7 14:06:05 CST 2010


> We'll see how this works out with the glue.  Fabricating replacement 
> parts might be a bit of an undertaking -- some of the fingers are like 
> the ones in my photos, a single, small plastic unit maybe a few 
> millimeters wide.  I can see fabricating new ones, though they're small 
> enough that precision might be an issue.  Others are part of a larger 
> set of fingers on a single "tube"of plastic maybe 6-8 centimeters in 
> length, these I suspect it will be difficult to replace.

What I would trty to do in the latter case is make the spindle and fingers 
separately (the latter having a hole for the spindle, of course) and then 
fix then together using either setscres, solder (soft solder or silver 
solder) or loctite. Not having seen the machine I don't know if this is 
possible, of course.

> 
> >> The bad news is that even with the mechanism fixed, the machine still
> >> exhibits the same problem.  I'm wondering if it's the delay line memory
> > Other than the physical damage, do you have any reason to suspect the
> > delay line system at thiis point?
> 
> Not really.  The physical damage was such that the dent looked as if it 
> might actually be deep enough to be touching the delay line wire inside, 
> potentially dampening the pulses.  I opened it up this evening (had to 
> gently hack off some rivets holding it shut) and gently hammered out the 
> dents in the aluminum enclosure.  No difference in behavior after 
> reassembling it and hooking it back up, alas.  But at least I can 
> eliminate that particular aspect as a problem.

Indeed yse. As I read someehwere the comment 'I've checked every darn 
compoennt in the <foo> circuit and I can;tfindanything wrong' should 
imply (assuming that the tests are valid) that hte problem is not in the 
<foo> circuit but elsewhere. And that is a step forward.

> 
> >> up a service manual.
> > Did such a thing ever sxist?

> I hope so.  I'd guess that a machine like this, of this vintage, would 
> have such a manual.  Not sure where to find one, though :).

I wonder if it was ever available outside the factory, thohgh (some 
companies did not release service manuls :-(). Or if it contained full 
schematics or if it was what I generally call a 'boardswapper guide'. HP 
cdesktop cacluator service manuals are invariably the latter which has 
caused me to spend many hours with a contiuity tester, pen and paper...

-tony



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