0x0031 - Casio 121-L Calculator Restoration

[@C6438911]

A good guide to how to approach cleaning and restoration of vintage devices, at least the first steps how to go about it. And preserving a piece of history in the process. And like others have mentioned, you have a gift for making video's and explaining what is going on. They are very good! Thank you!

[@PaulHuininken]

733 is the date-code. When they started counting in the early '70, they just mentioned the least significant digit of the year. So: 733 is 1977, week 33

[@michaelturner4457]

I'm pretty sure it's not 1977 this 121L was manufactured. For one thing it has Casio's old logo which they changed to the current one 1973. Also on the Hitachi chips there's things like 2M and 3C, so for these with Japanese date codes, 3C is March 1973, and 2M is December 1972. The letter represents the month, ignoring I. In additon a 1977 Casio would have been a lot more integrated than this, with only 1 or 2 chips.

[@PaulHuininken]

@@michaelturner4457 thank you for the complete info. Love it.

[@albertolucca8187]

i realize Im kinda off topic but do anyone know a good site to watch newly released movies online ?

[@coltenraphael1268]

@Alberto Lucca i watch on flixzone. You can find it on google :)

[@AgentJeffy]

Puhleeeease keep doing electronic repairs. Quite relaxing to watch the ups and downs and helps me out when I'm doing them as well. Soldering techniques, troubleshooting steps etc.

[@leisergeist]

What a neat little thing! I've never seen reed switch keys before, that's real clever.

[@hotplatelabs]

Owen Wilson has “wow” and AkBKukU has “this”. It’s a wonderful thing.

[@brianmangan2459]

I really liked this series of videos. Personal favorites include repairs and cleaning/restoring.

[@denniswoycheshen]

Oh man when he pulled the plastic off I cringed expecting the “cut” to come off with it. This calculator is amazing. The cable management is beautiful and reminds me of old school telephone central office wiring.

[@fryersoncaptain]

5:16 That's clearly a phone company asset; it's stained with coffee.

[@SnapshotTube2]

This is my new favorite channel. Watching this is like tech therapy.

[@Rightlime7923]

this dude surely does like to go back in time.

[@richfiles]

Remember when testing a lot of these old devices, that many chips use open collector outputs... They don't automatically swing high and low. You have to provide pull-up resistors, hence so many resistor packs used in this for pull up. It also means that if it's at ground, and you are referencing ground, then the chip is actively pulling down the output to ground, and you'll measure nothing. It's also entirely possible that that's not overflow, but a negative indicator.

[@alexpaww]

Please keep doing repairs/restorations! I love them in your style :)

[@LightTheUnicorn]

Wonderful little calculator. If you're going to collect things, they may as well be functional and have some proper vintage charm!

[@MikeSmith-sh3ko]

I have got one of these calculators and the bulb is a negative indicator. Mine was open circuit when I got it and with no current flowing in the bulb the meter didn't show much ether. I replaced the bulb and it worked. As a negative Massa indicator.

[@archville82_99]

i'm not even interessed in calculators but i found this very nice to watch, thanks

[@Redspl]

Nice calc! At first, I thought that the lamp might be a power indicator, but judging by where it's connected, it's probably not the case. It might be a component that was put into the circuit, but never actually programmed to be used.

[@user_romanport]

4:06 So beautifully over engineered

[@themilestonelp1524]

Looks like its going to be a great video!

[@eduardoavila646]

Nice calculator! The closest thing i have to that is a standard business calculator from, i think 1999. It still works pretty well, and still runs on some AA cells, i was thinking in getting some rechargeable ones there. Or maybe, just put a psu that outputs its voltage, as it aways stands in the same table, maybe using dummy batteries made out of plastic.

[@bikerdave1274]

I can hear Dave Jones Squealing with delight 😋

[@Carstuff111]

Good to see I am not the only person that uses a Sharpie to hide flaws or "repaint" something :P

[@SidTheGeek]

Those are pretty heavy for my table. that was nice work bro 👍

[@BackForwardPunch]

Are you interested in a Casio CQ-1? I have one that doesn't turn on but it is cosmetically in great condition. It'd be cool to send it to you to see if you could get it working and add it to your collection. Edit: I also have the carrying case!

[@TechTangents]

In about 2 weeks I plan on opening a PO Box. I would be up to the task of attempting a repair of something like that. I'll be mentioning it on Twitter and in my Discord server when it's ready. So if you still want to send it then you can check there to see when it's ready.

[@DanielBull]

I've got one of these in lovely condition. It works great during addition and subtraction but mostly falls over during division and multiplication. I'm guessing it needs a recap or some PSU adjustment. Not managed to find a service manual or anything though unfortunately.

[@Crazytesseract]

Shigeru Kashio worked very, very hard to help his sons establish Kashio. He alone moved the first prototype calculator uphill using a wheelbarrow. Then Tadao and Toshio worked extremely hard to establish Casio computer co., Ltd. They hired clever, loyal engineers, and workers. Most people remained loyal to the company for a long time, as in most Japanese companies. They were determined to make products built to last. This quality continued upto the early 2000s and even up to 2015, even with manufacturing moved to China and Thailand. But of late the quality is going down, especially Philippines and Thailand made products. One calculator made in 2016 in Philippines failed within three years, three keys went totally non functional. I have a 2008 China made calculator that still works in 2022 (14 years), a Japan made 1994 calculator working with a few segments not working.

[@MrHBSoftware]

so on one side of the lamp you have 14 volts and on the other you have ground commuted by a transistor. you were creating an overflow situation so the transistor should conduct, you were measuring voltage in relation to what?measuring ground in relation to ground gives you zero...you should measure ohms from chassis ground to lamp ground i guess...but i probably missed something.... it also seems weird that both the lamp and the IC failed at once...if the IC fails the lamp will no longer light so it will not go bad unless someone bumped the calculator very hard....maybe the transistor shorted and the light stayed on till it burned out? you should go deeper on that mistery

[@mikeyX101]

Dude gimme that magic, I need it.

[@bravo1oh1]

Great channel and content

[@KK4CNM]

I know this is an old video but if you need to paint something silver again do in the future try using a molotow "liquid chrome" pen they are excellent and gives things the luster of chrome plating.

[@whoyoucallinpinhead3451]

how did akbuku make a calculator video interesting

[@3800TType]

I have one of these where the subtraction key does the same thing as the addition key, the two lower "equals" keys in the corner. It's been cleaned inside, any ideas what causes this?

[@xXELevenXx1]

You should replace the lamp with a test lamp to just see if there is any change maybe it lights up

[@eduardoavila646]

Jeroen VS Nah, the multimeter awready says it doent have any voltagr applied. Both the lamp and the output are fried/non-funcional

[@Linkhunter]

i got brother 821L i got it from my teacher in the 90s lol

[@bsharpmajorscale]

I wish I could do something like that - I saw an old calculator at a nearby ReStore but I couldn't get it because I don't have the space to store it. :(

[@MrHBSoftware]

no space for a calculator?

[@JacobTechShit]

i took the challenge of looking up all the ICs i could find on the calcmuseum website, and this is what i came up with: here's the manual: casio.ledudu.com/images/calculs/casio/manuels/121L_en.pdf here's the product catalog, which confirms the casio 121-l was in fact available for purchase as early as, or earlier than 1973: casio.ledudu.com/images/calculs/casio/goodies/catalogue1973.pdf here is another site, which further proves the data of availability, this site states that it is ~1972: www.calcuseum.com/desk_13854.html unfortunately, i still have not been able to find any schematics for this particular model... i'll let you know if i ever manage to

[@JacobTechShit]

also, the border on the keyboard is supposed to be silver, and the case should be black. the oldest IC i found was this one, which is from 1969: www.calcuseum.com/SCRAPBOOK/BONUS/20120/1.htm the one that was giving the red light trouble is this one: www.calcuseum.com/SCRAPBOOK/BONUS/20660/1.htm hopefully a schematic for the calculator, or the IC will surface somewhere on the interwebs soon :)

[@BobofWOGGLE]

description says anther instead of another

[@TechTangents]

Thanks, fixed

[@Josh.Davidson]

Shouldn't this be 0x0031? Nice video though!

[@TechTangents]

Woops

[@qwertykeyboard5901]

15th?

[@MrValentine1915]

I have a Casio 121-F for sale.

[@1NIGHTMAREGAMER]

I'k a wifi card that's 100% compatible with win 98 se plz contact me if u wana know what it looks like and what uy need to do to get it work lol