3 Dec
2010
3 Dec
'10
1:31 p.m.
Hi all --
Got myself a Friden 1162 desktop calculator. This is from about 1968-69
and has a neat-O keen CRT display and uses a magnetorestrictive delay
line memory. Kinda cool.
Sounds very nice...
[...]
The 1162 has a rather interesting keyboard encoding
mechanism (you can
see a decent overview of the device & the keyboard mechanism here:
http://www.oldcalculatormuseum.com/friden1162.html) Close investigation
of the keyboard mechanism on my specimen reveals that a few of the
plastic "fingers" that are positioned on the rods that move the magnets
to/away from the reed switches have snapped off.
I have a close up picture of what the fingers are supposed to look like at:
http://yahozna.dyndns.org/scratch/friden/normal-finger.JPG
And a picture of one of the broken ones at:
http://yahozna.dyndns.org/scratch/friden/broken-finger.JPG
The broken fingers no longer make contact with the mechanism, and so a
couple of the reed switches do not get activated properly. I'm guessing
that this is at least part of the reason the machine is acting the way
that it is (that it's getting unexpected scancodes from the keyboard and
going off into the weeds...)
I need to figure out how to "recap" these fingers. I don't have a lot
of experience repairing plastic stuff like this, anyone have any
suggestions?
A number of plastics become brittle with age, and I wonder if this has
happeend here.
In any case, I have had very little success in trying to repair things
like this. I have found the best thing to do (and you won't like it) is
to make new parts. Do they ahve to be plastic (e.g. for insulation)? I'd
want to use brass rods and make little 'cams' to fit on them (secured by
setscrews [1] against flats on the shaft). It wouldn't be oriignal, but
it would almsocertainly be stronger.
[1] A tirival hint. If you need to use small setscrews (grub screws), I
suggest getting allen-hex ones. You can put one on the end of the hex key
and use the latter to get the screw into the hole.
-tony
