HP 41C programable calculator


While in college in the low 80's, I bought a HP 41C programable calculator. Recently, when I turned on the calculator, the word "Batt" showed in the screen. I changed the batteries(Duracell N)and now the calculator will on operate. Some one told me to remove the batteries for 24 hours to remove any static electricity that might be in the calculator. I did this with no results. Was suggested further to junk it and buy one of the newest that is on the market. This calculator is like an old friend that I hate to depart with. Hope you all will understand. If the cost isn't to great, I am willing to spend a few bucks to get it up and running again. If someone will supply me with someone who might be able to fix my problem calculator or suggest another remedy, I would appreciate it. Thanks, Bob


Clean the battery springs and battery contacts with a q-tip and isopropyl alcohol. Anything green or blue growing there (oxidation and battery salts) will prevent operation as it only draws microamps of current. The metal has to be *clean*. DO NOT scrape or sand!!!! That will only cause more trouble.

If you still have problems, it may have some cracked internal screw posts. Just post again and we can take it to the next level if needed.

Good luck.


I am interested in the same subject, just because my HP41CX seems to drain batteries at a very fast rate....
I can not understand what a "q-tip" is: please would you be so kind to explain in further detail?
Thanks a lot.
Cheers. Giancarlo


They're little sticks with cotton wool at the end. "Wattenstaafjes" in Dutch, but that probably doesn't help you very much either. ;-)

Here's a picture.

- Thomas


thank you for your tip!
The Dutch term was not helpful, indeed ;) but the picture definitely was!!
Thanks again.


Thomas, thank you for your tip!

You mean "thanks for your Q-tip" :-)




I know this as cotton swab (q-tip a commercial name?). Now you don't need it anymore, but at least I've just learned another word in Italian: "cotton fioc", according to "Dizionario De Mauro Paravia":


In Portuguese (Brasil): "cotonete" (There is no such a thing as Brazilian Portuguese).




Though the thread goes completely off-topic, I'd provide you with the beautiful German "Wattestäbchen".
Don't ask for pronunciation directions.
Hope the Museum's forum software can do umlauts...

Bob, keep your 41!



What about a calculator care multilanguage dictionary? So far we have one entry and four languages. And we have umlauts, tilde, cedilla, etc too: ä, ë, ö, ü, ç, ñ, ã, ...


Hi all,

In french, you should use the word "coton-tige".

Have a nice day!



Leaving the calc without batteries overnight means discharging the capacitor. The same can be done by hotwirering the battery contacts. While doing this, I observed (on my 41c) that the voltage drops very slowly, meaning you will have to short the terminals for about 10 min to get to 0 Volt. A good cleaning of the boards is the first thing I would do, open the calc and clean with destilled water or "contact fluid". I afterwards you can't screw it together tightly, put some sponge or polyfoam in to ensure proper contact.


The distilled water is just fine (suggest waiting for the unit to fully dry before applying power again).

However, if you are suggesting using Contact Lens soaking/disinfecting solution (a.k.a. saline solution), then NO! DON'T DO IT!

All "for in the eye use" solutions contain a specific concentration level of salt (Na-Cl) that will not be good to leave behind. Tap water would be safer than a deliberately salty solution. You will leave a small amount of corrosive alkaline salts behind in places that are hard to reach and are not guaranteed to be able to completely remove once deposited there.

Most people have the mistaken assumption that it is the water that kills electronic things that get wet, when it is the contaminates that are the problem.

And the big problem with active circuitry is due to salts that when in solution split into ions to permit charge flow between different potentials of circuit nodes that act as anode/cathode plates in the solution the device finds itself bathed in (read spilled on).

Hope this helps for the less chemistry minded among us.



Sorry, contact fluid = fluid to clean electronic contacts, NOT contact lens fluid!


Whew! That's much better. Amazing what comes to mind depending on the choices of words used and our own experiences and cultural biases.

Of course, we're such a diverse group, and from many parts of the world, it's surprising we can figure out half of what everyone else is saying.

The problem with a somewhat generic description is that you don't always know what kind of solution is being discussed, if it's not in your own phraseology. Just as bad are brand specific references which causes dilution of a trademark, and only works for those who have seen that brand.

For instance, I know what a "Q-tip" (cotton tipped swab) is, as I have had that product in my own hands many times. Also I know approximately what "TV Tuner Contact Restorer" aerosol cans contain (something from a bygone age now that most TV/VCR's use synthesized electronic tuning circuits), and would be loath to use it indiscriminately for "cleaning" other electronic stuff. The oils left behind might be worse than the original problem.

All for now.



Hi Bob,

Fear not, you are in good hands here.

Randy, Luiz, and many others here have surgically repaired hundreds of these marvels and if you go slow and steady with their advice you will stand a good chance of recovering your machine.

Was suggested further to junk it and buy one of the newest that is on the market

A classic case of the uninformed believing that progress is always onwards and upwards without actually checking on the details of it.....there is no new machine on the market that will replace a 41....

The 41 is a machine like no other---though I did not grow up on that particular one.

If in the unlikely event that your machine really will not recover, there are still other ways to make a 41---even by software emulation---as well as surgical transplantation.

Best regards,


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