HP 41C replacement LCD display?


Anyone know where to procure the replacment LCD for this model? Exponent numerals are obscured by black due to an unfortunate drop.

s/n 2032A02705


The only source is another HP41 calculator. Replacement of "half nut" LCD screens is basically not possible without doing extensive damage to the machine.


What is "half nut"? I'm not familiar with that term.



Hi, Vince;

try this link, scroll down some three to five times (depends on your video resolution) and you´ll see the title HP-41 Versions. Right after this you´ll see the image

Check your HP41 and you'll probably see the difference.

Indeed, removing a halfnut LCD demands patience, good soldering iron, ESD protection and some precautions (electronic maintenance expertise is desirable). I have already completely disassembled a halfnut LCD and I scanned the disassembled unit and parts. I'll just find the images and post again.

Best regards and success.

Luiz (Brazil)

Edited: 23 Aug 2005, 4:08 p.m.


Based on the serial number, you don't have a halfnut unless HP swapped the case back when it went in for service sometime after 1985.

The real issue is that David is correct - the only source is another 41. But, if it is original, you have a fairly early 41C. There where changes to later models so not only do you need to find another 41, you'll need to find one from about the same era. Later lcd driver modules where physically larger and will not mate to an earlier lcd nor will they fit into an early case. Early, square epoxy encapsulated chip versions are not compatible with later cpu's.

With all things considered finding a replacement part, you might just want to buy a used CV and be done with it.

Edited: 23 Aug 2005, 7:45 p.m.


It is possible if you wanted to save a little money that you could
buy a 41C and remove the processor / memory board from your CV and fit it to the keyboard / display front half sheel of the purchased 41C. The keyboard / display unit is electrically identical between
the C, CV and CX to the best of my knowledge.

The prblem is that all these units are getting old and the plastic
components fail, leading to fatal problems with the interconnects, which connect under presure. I'm doing some research into this problem to try to extend the working life of the machines another five or maybe even ten years. I wonder how long the LCD units will last?



What is the issue with particular LCD drivers and CPUs?

The service manual mentions the auto-power-off problem, where you have to change a capacitor on the logic board if you swap between early and late LCD drivers, but apart from that I can't find a problem.


It has nothing to do with CPU's...

The early 41's used LCD driver module 00041-80003, they were 16.5MM in height. The later models used 00041-60146 modules, they were 17.5MM in height. The 17.5MM modules do not fit into early 41C's without physically stressing the assembly. The keyboard mold was later modified to accept the higher LCD assembly by removing the heat stakes along the top row. The 00041-80004 pcb was later modified to remove the holes altogether, some units had holes in the pcb but no heat stakes during the transition. The unit on right shows the top row heat stakes in an early steep key 41, the left, a later CV.

The lcd's used different connection technologies (gold over copper vrs elastomeric zebras) and were of course different dimensions and therefore not 100% physically interchangeable.

Edited: 24 Aug 2005, 10:14 p.m.


My 41C has never been serviced so it can't be a half nut. It has sharp corners.

I'm hooked on RPN (25 years) and would like to repair it or replace it. I guess I should have done it 10 years ago when the 12C was affordable.

What does a parts quality 41C fetch these days? Are there folks on this forum who stock these parts? What can I expect to pay?

Alternatively, is there an inexpensive less complicated RPN calculator avaliable today??


Sorry about the typo, I meant to say 11C instead of the financial 12C.



"Alternatively, is there an inexpensive less complicated RPN calculator avaliable today?? "

The cheapest available RPN calculator would appear to be the HP 33S, now in production by HP and costing around $50. It has a somewhat weird (to old-time HP afficionados!) keyboard. It looks more like a cell phone keyboard. It is available at (at least) WalMart and Frys.

This model has been both praised and panned here at the Museum, but the general consensus appears to be that it is at least OK, after you get used to the keyboard and the somewhat miniscule decimal point (which is said to be improved in the very latest models).

I'm sure others will add more (or subtract from) my comments!


Sounds like an affordable alternative. I will likely be posting for sale my 41C, printer, cardreader/cards, 3 single memory modules,quad memory module, manuals and boxes soon since fixing the display is probably not worth the effort.

Thanks to all of you for your assistance!!


Hi Vince. I have a replacement display for sale from a junked 41C
fullnut. If interested, please write to me.

Don Wallace



Sily, silly....

"LCD display?" That's kind of like the "HIV virus," and the "ATM machine."


Yes, I KNOW!

I felt silly writing it, Volguus...

Thank you for bringing it to everyones attention!

But then you never hear about people just saying LC display,
do you? And LCD is for Lowest Common Denominator, just ask Valentin A...

At least it isn't a teutology (bad spelling??) such as:

Awfully nice, terribly good, military intelligence or
customer service... (just kidding, folks...)

(And NO! I am NOT a communist, Bill ;-)


What do you have and what do you use it for Volguus?


HP41 parts withdrawn. I have my early fullnut fully fuctional now!


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