world's ugliest 15c about to die?


The world's ugliest 15c, ( after more than 20 years of daily use as a surveyor's tool, now requires heavy pressure to use the keys. Is there a fix for this short of replacing the calculator?

Charlie O. in Phoenix


Fix that might be able to repair. At the cost of Hp15c's it might even be worth it (though that paticular 15c may not except out of a perverse pride).

Older 12c's should work for a keypad donor.


First problem is the WD40... Wanton Destruction 40 is a wax... it will gum up just about anything it touches including key switches.

Your best bet is to open up the machine and clean each key switch contact. Make a small wire brush out of three bristles inserted into a pin vise, twist together, and trim the end square with cutters. Under each key is a breather hole. Place a drop of 91% isopropyl alcohol on a hole, dip the brush in more alcohol, and the "scritch" around in the hole with the brush. Be careful not to break a bristle off in the hole. You will probably have to rebuild the brush every few holes.

If it were mine I would first run the machine through three cleaning cycles of an ultrsonic cleaner. Use distilled water and change it each time. Shake the unit as dry as possible between each cycle. Finally dry it for around 24 hours in an oven on low (<140 degrees). This technique does have the potential of damaging the machine, but it has worked wonders on some really bad cases.


re: "Finally dry it for around 24 hours in an oven on low (<140 degrees)."

Or, since you live in Phoenix, just wait until this summer and leave it out in the afternoon!

Dave - who lives in Las Vegas - we appreciate Phoenix in the summer because seeing the temperature there almost makes us feel cool!


A closed up car in the sun will do just fine. Keep the machine covered. Don't leave the dog or kid in there with it.

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