Calculators are special purpose micro-computers.

10 responses total.

My HP-65 broke down some time back. The card reader would "scream", and
reading was flaky. Also, the battery died - and where do you get a new
battery for an HP-65? Radio Shack! - a 3-cell NiCad unit. Its not hard to
modify the original battery frame to the replacement. But, the card
drive.... I finally took it apart, cleaned things up a bit, and found a
broken connection for one of the 5 wires to the ... drive position
digitizer? Now, the card drive purrs like it used to. However some of the
keys don't make good contact. Is there a solvent into which one can dip
the whole calculator, to clean out grunge from the contacts? 100% alcohol,
perhaps? 

maybe purchase radio?

I'd rather buy it bulk, not in pricey spray cans - and you don't know
what it dissolves until you try it. 

Trichlorethane 1,1,1 (apologies about the spelling) is a fairly common circuit
board cleaner... or was, since it is pretty nasty stuff.  You may still be
able to buy it in an 8oz. can as "Energine Cleaning Fluid".  I got my last
can at Meijers a few years ago.  It's still half full.  It's great for
cleaning electronics, but these days makes me nervous to use.

There are plastic parts on the calculator board (after removal from the
case and buttons) that I think would dissolve in TCE, especially the data
card drive assemblies, which appear to be polystyrene or acrylic moldings.
An alcohol or naphtha may be safer, but even those dissolve or soften some
polymers. It would be possible to swab the contacts, though not easy, as
they are made from metal strips that "pop" down when pressed, all
assembled by spot welding as a single unit. There is very little space
between the "pop" strip and the board (I could pass a strip of thin
cardboard through, but that did not clean the contact surfaces). 

This is, of course, somewhat of an antique restoration project. The HP-65
was quite a marvel when it first appeared. A consulting client bought two
and gave me one and I programmed the calculations that he needed in a
research project. 

Maybe TV-tuner cleaner?  I've successfully fixed keypads with this stuff, 
by taking them apart and spraying down the contact pads.

Don't dunk the whole calculator in cleaning fluid.  Take it apart and spot
clean as needed.  I like TV tuner cleaner because it also leaves a film of
lubrication which reduces future oxidation.

OK. I'll have to device a swab to go under the "pop" springs - the gap
is pretty small. Who has TV-tuner cleaner? Purchase, and??

Radio Shack has a pretty good variety.  I once used it to clean up after a
careless tech who thought that Cramolin should be used like Holy Water at an
exorcism.  ;)

Yeah, Radio Shack's got it.  If you're lucky, maybe you can still get the 
kind with the CFC's in it. ;)

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