I would vote preserve it. These things are not common and there wont be much on the other side of the PCB.

Don't break it, it doesn't deserve it.

EEVblog Please keep the calculator intact. I would rather see a brief video about how to program that thing. Thanks for all the great stuff you do.

I vote for preserve it. It's almost as old as I am (42nd week 1987) and rare specimen of it's kind. There is plenty of stuff to tear apart, modern CFL's for instance (prepare for horror though if you open one apart).

Dont go any further dave, that thing is a beauty!

PLEASE, Dave -- leave this beauty in working condition. As we can easily obtain a defective unit cheap on ebay, for complete teardown anyway..;)

The most beloved calculator of my life. Still using one HP41C from Ebay today an HP42S and the HP42 App

My first was a HP-25C, a present from my parents in '77 for getting into mechanical engineering at UNSW. It lasted me till 83. It was old by then but I just loved it. My first programmable computer.

I still have my 41C from 1981, and it still works. I don't blame you for not ruining it - I certainly wouldn't want anyone to break mine.

I managed to get one of these calculators when my employer told me I could have a calculator for my job. It was really good and had a lot of cool features.

Leave it alone. Its nice as it is, and useful.

Don't bother taking it apart further. We've seen button matrices before, and you can pretty much figure the rest out by looking through the board itself. It'd be more interesting to see it working - show us the features that made it last 10 years. I.e explain why a programmable calc is better than some crappy Casio we can buy for £5.

Don't do it.

Leave it alone :-)

Don't do it Dave! There must be a dead one somewhere to butcher.

i realy liked how you hold back to destroy such a great device, especially in a teardown video

I vote to respect this thing ! Don't take it apart further. There is obviously some space for a side power connector or something. Interesting.

Don't destroy it. I have a 41C where the previous owner forgot to remove the batteries, so the Flex and PCB contacts are destroyed - It's destined for the bin in that shape, unfortunately ... Also, the electronics is a whole lot different. I could send it to you Dave? You can destroy that one without problems.

Sweet! Another awesome video!!!

Preserve it. I doubt it'll be worth it underneath to destroy it.

Don't drill a piece of history dave!

No don't go further. I think that there not much more than the buttons. make an x-ray first to see if it is necessary to continue the teardown.

Leave it, pictures of the other side can be found online as noted below.

Don't ruin it!! There is nothing of interest on the other side. Other teardowns have shown this.

Ok. Finished the video. Awesome that it survived so far, as such i vote that it survives longer. There are some things that can't be opened.

Just an off-topic comment (pertaining to all EEV videos) ... the editing and photography are super ... the macro stuff as well as the std. shots ... nicely framed ... the wide-angle shot of whole 41CV, near the end, looks very pro. KZfaq Oscar Nominee -- Best Cinematography

HP: the original apple, gluing their shit shut.

Nice to see inside a newer HP41CV. The older ones with the separate main board packed with components is far more interesting though.

Respect it

I agree... Leave this marvel of design intact. I would love to learn more about that amazing, early chip.

When I was in the 4th grade, my father and I (mostly my pops) wrote a program that would provide the remainder after a division operation. It took us a couple tries to get it right. Great memory.

Respect HP, don't break it! :-)

Don't do it! It's a beautiful work of electronic engineering art and it works! It'd be a great shame to ruin it!

Woohoo, love teardown Tuesdays

Save the HP! Surely someone else has a dead one you can cut open. It would be nice if it were an older one so we can see if the design was cost reduced along the way.

No doubt Someone has a crushed one in their junk box and could donate it for tear down. If it's not broke, don't break it.

The generous gods of KZfaq users should rule in the calculator's favor. Let it live!

Leave it be Dave. Far to cool to be in the junk pile afterwards.

I'd say leave it Dave, I'd have said tear it down if there's anything interesting, but we pretty much know how a tactile keyboard works, so ... not worth the hate you'd get :-) I'm with the others who say pick up a trashed one on fleabay

Wow, so many 'Don't do it's' and I agree also! I love old alpha displays, especially in devices that use them to full potential like that calculator seems to. Nice video of it's insides, perhaps if it were broken or an x-ray machine were available some time...

That event gives a relaxed feeling :)

DOON'T DRILL keep it working I can't watch you do something like that!

Respect the beauty!!!

I vote no do not take it apart keep it you love it way to much and Id hate to see you destroy it.

Leave it intact. I had one of these and loved it.

No no, don't do it, we've seen enough, well I have.

Preserve the Beauty Dave!

Long-time viewer, first time commenter.... DON'T DO IT!!!! We've all seen a keypad matrix before, don't need to wreck this classic machine to see another!

I just watched this again after opening mine up... from what I could find out, mine dates from February of 1983. The one big difference I noted, is that the speaker for mine is on the main board and not attached by a wire to the other half of the case.

no dont teardown anymore. keep it going another 40 years

Good Video! I wouldn't go any further with the tear-down; it would be a shame to destroy it. Besides, there's not going to be much more to look at unless we want to see the intricacies of the mechanical side of things. Quite impressive ;=) How about that Avantest R6142? That would be an amazing tear-down!

There is was also the CX which had a built-in RTC module. This was available for the 41C and the 41CV as well.

That Device is FAR too rare to destroy for our entertainment, working or not! DO NOT DESTROY IT!

The Beatles said it best; Let it be, let it be. Whisper words of wisdom, let it be.

Don't take it apart any further, it's not worth it. Maybe someone has a already broken one to send in so you could proceed with that one instead?

+EEVblog, Dave, perhaps the solution is to send it to Mike and have him x-ray it. He did a teardown of an x-ray bagage scanner some time back. If he still has access to it.

You're not missing anything on the other side. If anyone is interested in seeing the traces and metal dome buttons they can search the interwebs for it. The only interesting thing is the interface to the display which is more pressure contacts.

For those curious all the service manuals as well as everything else you could want to read about it is available on hp41.org website as a free download.

Anyone know where to find the replacement battery flex module and the z flex that drives the display. I'm told they exist (repop's) but can't find a source?

I still have my Dad's HP 97 programmable calculator. An order of magnitude older than the HP41CV. I also have all the original goodies, manuals, case, programming strips and books. Manual dated 1976, revised 1977. Good stuff. I remember my Dad using this calculator well as a boy. My Dad was, hold your boots on Dave, a petroleum engineer! Ha! He was the guy that would perform surveys and then run astronomical mathematical calculations to determine the yield of a specific site. He was also a geologist at heart and earned his degree from the esteemed Colorado School of Mines. His diploma is printed on a plate of silver.

dont go calling flatflex connectors innovative, they're a pain in the ass to repair and fail often

David please do not proceed any further on this one. It is a shame to damage an almost mint condition working calculator. If you can find one that is not working, then yes, go ahead, although I do not expect that much on the other side.

You say it yourself all the time. Don't turn it on, take it aparrrrrrrrtt!!!!

On the other side of the main circuit board is just the switch contacts. The interesting part is how the switches are made with springy steel, which give the nice click feel to the keys. If you do remove the heat stakes, do it by lifting, not cutting, so the centre part of the heat stake remains, and you basically lift off a donut shaped piece of plastic. Then, if you wish to reassemble afterwards, you can use a small amount of glue on each heatstake to make them hold again. A better tear down would be an older HP41c with separate processor board :-) Cheers, John

Can you replace the broken melted plastic bits with small screws and restore it after you fully dismantle it? Maybe some how save the broken plastic bits and re-melt it on with a soldering iron to rebuild it?

Actually I take that back. Leave it together, there's nothign much to see.

😄 Don't break the HP-41CV. That would be akin to taking a baby apart to see how it works.

Could someone explain to me, why are ther traces going to those plastic nail-things on the board? Are they vias?

Don't do it, Dave! Respect the HP! It's too valuable to tear it apart! Side note, my dad still uses both of his HP41C's. I've only got a shameful 49G+. No classic 41 for me.

How is the flat flex held securely in place? I see some plastic stakes at one end at the battery end. But then it wraps around and over some curves where the modules plug in. Glue?

Our whole office used 41's starting in '79. We all continued using them long after they were discontinued when the replacement 48S/SX came out. NONE of us like the 48... it was just too complicated for us. We had heard that the public was not happy about the discontinuation of the 41's. As our 41's started to wear out, most sought replacements on eBay and the like. To this day they bring more $ than they did when new. The same can't be said for the 48's. We still have a couple 41's in use her in the office!

Pull it apart! You are doing it on film, so you may save many other calculators being pulled apart to see the other side. Anyway you removed the original feet, so the originality of the calculator is no more!

Get a dead one on Ebay and take it apart, maybe even fix it :) Keep the nice one for yourself

My HP-41C had rechargeable batteries in a special pack that replaced the N-battery holder. Came with a charger too, of course.

So, what was the factory mod with the diodes and the cap?

I wouldn't destroy an example of vintage electronics in that good of condition. The earlier version of it did have multiple memory chips and a CPU mounted on a separate board. flickrhivemind.net/Tags/hp41cv/Interesting It seems HP was able to integrate everything single chip mounted to the same PCB as the keyboard by the late 80s so there's probably nothing interesting on the other side of the board.

Let it live Dave !

surprised to see those small surface mount caps from '87

The 1LM2 chip is just the CPU. It is a redesign (die shrink, cost reduction) of the earlier 1LA5 and 1LE3 CPUs. The architecture ("Nut") is unchanged, but the electrical characteristics may be slightly different. Aside from a small number of processor registers, all of the RAM and ROM is in the LCD hybrid, along with the LCD drivers.

No further teardown necessary!

Respect it, please.

Beautifull

Dave, keep it in one piece. I can't bear to see it die.

I had to look up the word 'Mantissa'. That's my word of the day, thanks Dave. I'd be curious to see what happens if you disconnect that bodge wire. Please don't take it down any further. Let time take it apart for us.

EEVblog - Please keep it intact

Nice calculator!

Why do you think there is a trace near the processor which almost looks length-matched?

Don't kill it Dave! We wouldn't learn much more any way.

What do you do with all this great stuff people send you? Do you sell it, toss it, give it away, return it to the original sender?

0:52 well you know.. the TI-83 and the ti-84 (amongst others) have also lived for over a decade so far..

Those plastic rivets are nothing a razor blade can't handle ;)

I would take it apart only after getting a 3Doodler - I've been using mine for more repair than anything thus far, it'd easily allow you to put the pcb back in place, restoring the construction

Whats the deal with the blue latch on the front? Does that hold the keypad in or something?

Don't do it, Dave! It is too nice a calculator to risk killing. There isn't a lot to see on the other side. I know. I've taken apart the HP-41CV I bought in 1981. BTW, the first two digits of the serial number are the number of years since 1960. For more information on the calculator, do a search for the museum of HP calculators.

X-Ray, otherwise leave it working!

This one looks like a modern HP41, it says Rev 6, and the IC package is modern (not DIP). I've seen other 41 disassembles on YT (namely one which didn't have any revision number, so likely Rev 1), and it was very different pcb, populated mostly with dip packages.

Don't take it apart, turn it on!

There was at least one other version of the 41CV that did have separate RAM chips on the processor board - Google "inside the HP-41CV fullnut". There are pics of the keyboard pcb as well - it ain't worth destroying a working 41CV to see what is already on the 'net. There was HP-41CX module later, too. I bought a 41C around 1980 with the card reader, math module and memory module. You could use it in uni exams - I programmed it to solve complex impedance questions that normally required a Smith Chart. Examiners probably wondered how I could get the answer right to so many decimal places! You could also use it to remember formula equations with the alpha display, at the time the uni didn't realise what that 41C could do or it would have probably been banned from examinations.

Don't chop it apart...but curious, do those standoffs come out, or are those copper rings in the pcb just surrounding the standoffs?

I just remembered.I think one use for these calculators was the computer of last resort on early Space Shuttle missions.