EEVblog

[@TheEPROM9]

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

[@Jellow2202]

I agree! Some low-res photos of the other side of the board can be found here: goo.gl/Lx4GUP

[@NorbertHarrer]

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.

[@ronaldhudson169]

Also I vote to not destroy the calculator - surely some one of us has a non-op unit that we can donate. (I don't I use a Swiss Micro DM41L)

[@Gyrxiur]

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

[@PeregrineBF]

And if you must break it, carefully cut off or drill out the heat seals, then replace them with nuts and bolts (with teflon washers as needed) and put it back together. That way the calculator will still work when you're done with it.

[@HighTechLab]

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

[@Mark.Brindle]

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.

[@1965wazza]

Likewise for me. My first was a HP 15C for mechanical engineering in 1983.

[@CurtCameron]

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.

[@THEtechknight]

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

[@Joe__Tech]

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

[@DjResR]

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).

[@hankus253]

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

[@CalculatorObsessed]

Glad you kept it together. There are so many ones where the case has got brittle and compression joints failed or damaged by leaky batteries. it’s good to keep a good one intact. The earlier ones had a separate board with discrete components, connected, and flex/ zebra connection to the keypad PCB. Less reliable as the plastics fail. There seems to be a bit of a cottage industry in producing parts to repair/ upgrade these.

[@quincy8557]

Leave it alone :-)

Don't do it.

[@mikedjames]

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.

[@TehHijack]

Don't drill a piece of history dave!

[@zaprodk]

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.

[@TheSuraj03]

Just mail it, he does not reply to you tube comments often.

[@mitchenerjosh]

You can buy a new flex cable for it: www.thecalculatorstore.com/epages/eb9376.sf/en_US/?ObjectPath=/Shops/eb9376/Products/Flex-PCB They sell out fast though...

[@zaprodk]

Joshua Mitchener Wow, that's expensive!

[@jamesgrimwood1285]

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.

[@0LoneTech]

It's pretty amazing what you can get from Casio these days - programmable models appear to start at just £20 or so. But this is the HP 41, an extensible computer. Where my Casio can connect to tape and printer, the 41 could connect to lab instruments, card readers, barcode readers, code expansions, and more.

[@20kilovolt]

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.

[@ChipGuy]

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.

[@USWaterRockets]

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.

[@nanoheal]

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

[@tubical71]

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

[@markistheone]

Respect it

[@CP140405]

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.

[@aserta]

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.

[@UberAlphaSirus]

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

[@TheNamesGunk]

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

[@fragalot]

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?

[@redtails]

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

[@pfsmith007]

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.

[@santo426]

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!

[@PeterCCamilleri]

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

[@EricSmith42]

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.

[@Fridboh]

Just to add, the updated version was called "Halfnut" in contrast to "Fullnut". An inspection of the LCD display easily reveals the version. Fullnut has angular corners while in the Halfnut they are rounded. Dave is clearly showing us a Halfnut.

[@douro20]

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

[@johnrobinson7034]

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

[@h0ll0wm9n]

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. KZbin Oscar Nominee -- Best Cinematography

[@ironman7261]

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.

[@sprybug]

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!

[@CalculatorObsessed]

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

[@frollard]

HP: the original apple, gluing their shit shut.

[@mushroomsamba82]

Woohoo, love teardown Tuesdays

[@hunorshands]

So do I! :-)

[@cemx86]

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?

[@trahim2]

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

[@WhitentonMike]

+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.

[@p00ky76]

hehe, I think Mike mentioned that his x-ray machine was out of action in his last vid but he's probably sorted it by now.

[@Desmaad]

He no longer has the conveyor belt one (he tore it down for parts and scrap because it barely fit in his garage). However, I think he still has a static one.

[@stmounts]

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

[@sbreheny]

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

[@JosefdeJoanelli]

14:15 The heat stakes also look like they go through extra large diameter vias, I guess to save on the number of holes taking up board space. Very thoughtful :)

[@MatthewAnson]

I have never seen this before. It us really cool though. Trying to think of somewhere to use it. :p

[@JosefdeJoanelli]

Never seen what before? The heat stakes? They are used all the time on cost sensitive stuff to save on screws. You can ultrasonically mold or just melt the plastic boss that rises through the PCB to form the plastic button. I have used them at work a little bit.

[@jgmrequel]

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

[@CharlesGallo]

I have mu CV - still in constant use

[@cybersed57]

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

[@artifactingreality]

surprised to see those small surface mount caps from '87

[@GaRbAllZ]

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

[@ronaldlijs]

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

[@whayden001]

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.

[@ipodfixerman]

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

[@ddrl46]

You have to switch the video quality back and forth for it to work.

[@frozenelectronics]

Sweet! Another awesome video!!!

[@youbecha64]

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

[@adumont]

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.

[@Corpsefury]

Respect the beauty!!!

[@DimitriRoegiers]

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

[@JaredReabow]

could you heat gun the pins and slowly lif the board so they melt out of the way, then when you re assemble you can heat them and push them down with something hard

[@powder-phun949]

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

[@KelvinW344]

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

[@AdrianTripp]

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!

[@elmin2323]

Please tear down a ti83 plus! I'll send u one if u like!

[@Revoku]

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

[@padraicmcguire108]

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?

[@11danzizzle11]

I hope the video is still processing because the entire video is black for me as of right now.

[@aserta]

Same here.

[@lukasandrysik3666]

It works for me, but it is only 360p now :-P

[@11danzizzle11]

Lukáš Andrysík Works now, first time this ever happened to me!

[@ironman7261]

Respect it i still have my hp41c from 1980 best calc i ever had. Have hp48 hate it.It went up on early shuttle missions for backup navigation duty if their were problems with main computers

[@Coolkeys2009]

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

[@Coolkeys2009]

Can you write some programs on it to demonstrate how it would be used in engineering, or use it to do design calculations in one of your videos.

[@stmounts]

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.

[@stmounts]

Here are the links to teardown images of both "halfnut" and "fullnut" versions- www.keesvandersanden.nl/calculators/hp41cv_inside.php www.keesvandersanden.nl/calculators/coconut_repair_fullnut.php

[@stmounts]

And here is the schematic for the "fullnut" HP-41C - NOT the one Dave has. members.ziggo.nl/kees.van.der.sanden/downloads/HP41C%20schematic.pdf

[@geeko321]

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.

[@shaun27ful]

Yes, all I'm seeing is a blank screen, but can hear the audio

[@casperhito]

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

[@kemalnottaturk2500]

I think that Halfnut has the Hyper mod. It is a clock speed doubler.

[@wdavem]

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...

[@natsumiyuki9173]

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

[@tomwaters86]

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

[@mikedjames]

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

[@AssembleAsomething]

no dont teardown anymore. keep it going another 40 years

[@DarkLink1108]

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?

[@MCCRITTERS]

Preserve the Beauty Dave!

[@jessegotowork]

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

[@mopar3502001]

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!

[@elleonplayero]

I would love to buy an HP41C and regain the power of these great calculators, where can I buy it?

[@petermikus2363]

Ebay or yard sales are you best optuins probably

[@Fridboh]

SwissMicros built a HP41 clone called DM41X. It's a bit costly but worth its price considering that you can load all those expensive ROM modules without additional financial burden.

[@SatyajitRoy2048]

This is really the art of manufacturing back in 80's

[@maximilianmustermann8172]

That event gives a relaxed feeling :)

[@frozenelectronics]

It hasn't finished processing the HD streams yet. It takes a while, same happens when I upload. He must have uploaded it right now and not 'scheduled' the release

[@frozenelectronics]

Keep refreshing, the HD stream usually only takes an extra 5 or 10 minutes, even on long videos. So far I only see 360p

[@lighty8130]

why isn't there any picture?

[@TheChipmunk2008]

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

[@andresgazso881]

The diodes and the capacitor is a mod to speed up the processor clock.

[@eddydutton4614]

Sacrifice one and save others. By opening one so others are saved? Does that work for you? I want to see inside, plz and thanks

[@sic-]

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!

[@frozenelectronics]

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

[@frozenelectronics]

Assuming you're actually going to USE it for something, that is...

[@keshabapatel8322]

DONT TURN IT ON....... TAKE IT APART!!!!!!!!!!!

[@BillSnitzer]

No further teardown necessary!

[@Patchuchan]

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.

[@curiosity2314]

Other tear downs have probably shown what is inside.

[@wuwo9348]

Hey Dave, interesting teardown You missed something which confused me the whole video: between Pin2 and Pin3 (counted from the right) of the FlatFlexConnector coming from the upside comes a trace - and get lost! No via or anything. It ends at the DIP connector in the upper right. Looks like the designer ran out of steam - or is it some RF-Funny-Thingy? ;-)

[@JRBlood]

Respect it, please.