I've got a pretty beat up HP-41C (That I probably paid too much for on eBay) that has two segments on one character not working on the LCD. Does anyone know if this LCD is available? (Other devices, other calculators, digikey?). I have already fixed the screw posts, the battery contacts, one soft key, and the speaker piezo, so this is the last project left on this calculator. Thanks for any help!


The part won't be available from HP anymore, your best bet is to get a dead donor calc with good display. But, there are some differences in the displays in 41s, i.e. halfnut vs fullnut, and even within the fullnuts there was several revisions of the display. It would be best to get a donor calc with a serial number similar to that of the calc you already have, as I don't know if the displays are compatible. - John


john - sounds like he got a dead doner calc already.... and fixed it. nasa (or hp) should hire this guy. - db


How do you fix the soft keys ?


How I repaired poorly functioning keys on HP-41 calculator -I took the keyboard apart cleaned things (with ether - starting fluid) and put back together. Keys were worse. Took it apart, cleaned some more, and put back together. Nothing worked. Thought seriously about throwing $50 piece of &^%# in garbage -- didn't. Thought seriously about leaving terrible feedback to eBay seller who sold me the &%#$ calculator -- didn't. Repeated these step several more times over a period of several days until through sheer blind luck everything worked. Vowed never to take apart another HP-41 keyboard.


It's not difficult to get the keyboards apart and to clean them. I've done hundreds of them. But (1) NEVER try to clean the whole thing! It's covered with a sticky glue and you'll only spread it around. Only clean the clicker disks and the contacts on the circuit board. (2) the real trick is getting them back together. First you have to make ABSOLUTELY certain that all the keys are working cause once you put it back together, it's next to impossible to get it apart again. Second, you have to PRESS the circuit board back into the case TIGHTLY or the keys will be lose and rattle. Finally you glue the circuit board back n with superglue. You have to be carefully not to use too much or it will flow into the keys and prevent them from working.

If you don't want to tackle it yourself, I charge $40 to repair them.

Sorry, I'm not NASA qualified. I know the difference between meters/second and feet/second.



Joe & all,

Give NASA a break. The travel agency said Mars was metric, just like Canada and major American universities. Plus, anyone can goof. One year I heard Santa forgot to make an adjustment after leaving the North Pole and gave all the Republicans nice gifts instead of their customary lump of coal!



Hi John, I have an old and ugly 41 too. About the display there was two segment of last character (seeing only when EEX function or ALPHA is ON) not working. I fixed them opening the calc. and then using an hair dryer with very hot hair on the back of display for a few seconds... first half display became black and I thought it was destroyed, but after two or three second I restart the calc. and all display was fully functioning, bright and as new included segments who was broken... Well I don't know why all that happened but since then three month had passed and my loved 41C is still fully functioning. Greetings!



Did you use an "air" dryer with very hot "hair" ? Or was it the other way around? :-))


... yes it was a terrible mistake... hair was normal :-) it was hot air... Same mistake happened when someone italian asked "orange jewish" at supermarket! :-)


Gianmaria: I hope my comment didn't bother you, sure my english is plenty of such mistakes. BTW, I am recovering my flight simulator for the HP41, so I hope I will get to you soon with news about it. Andrés

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