Nixie Tube Calculator - 1972 Monroe 620 - Repair and Demo
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- เผยแพร่เมื่อ 22 ก.ค. 2024
- After a long wait I've finally got myself a Nixie Tube Calculator (or more correctly, a calculator with a Nixie tube display - it doesn't calculate nixie tubes!!!). The Monroe 620 was made somewhere around 1972 - I think there's a date code of November 1971 on the Texas Instruments chips, so that would put the calculator into 1972 or thereabouts. This calculator and others in this series, was actually made by Canon and placed in a Monroe case.
The calculator was in a pretty bad state when I got it, the case was badly damaged, the circuit boards were filthy and some (most) of the capacitors were reading incorrect values. Once everything was cleaned, some components replaced and the case repaired, the calculator started playing up - the problem eventually being traced to a bad via on the keyboard PCB.
The Nixie tubes in this machine are marked as:
JRC
B-5755
K114E2
Made in Japan
If you're interested in seeing some other vintage calculator repairs and demos, I'll put a few links below:
Hitachi KK561 repair • Vintage Calculator Rep...
Hitachi KK561 Demo • Vintage Calculator Rep...
Friden 2002 repair and demo • Vintage Calculator - S...
Madas 20LZVG repair and demo • Calculating Machine Re...
If you want to see some beautiful nixie tubes being made, head to Dalibor Farny's channel • The Art of Making a Ni...
Start 00:00
First Look 00:37
Power Supply 01:16
Pre Testing 02:55
First Test 04:14
Case Repairs 05:00
Power Plug 06:10
Keyboard Fault 06:30
Demo 08:39
Divide by Zero 14:45
The Nixie Tubes 15:17
Outro 16:44
If you've enjoyed this video and you'd like to help support the channel, you can make a one off, no obligation donation, using the PayPal link below:
www.paypal.com/paypalme/Grump...
Outro Music
"As Yet Untitled"
by GrumpyTim (available to download from GrumpyTim's Bandcamp page)
grumpytim.bandcamp.com/
www.grumpytim.com - วิทยาศาสตร์และเทคโนโลยี
In college, we had a course called, “Business Machines: Computational”. we had these models for learning how to quickly key the calculator without looking at the keyboard. We also had units that covered the traditional mechanical calculators. The one carriage calculator was broken for most of the quarter so we skipped those units. This was a college in Tennessee, USA so we didn’t get updated technology until way after I’d graduated. It was nice to see the Monroe again with the nixie tubes. These were some of the most reliable machines we had seeing all the abuse the students gave them. Some of the offices had them, too but a lot of them had printing models with no displays.
Hi Stumpybear60, that would have been so cool using these machines back then - I think new technology from the 70s was really exciting. I love the Nixie tube calculators, they're beautiful things to look at, but I also have a lot of time for the printing only machines, some of those made the most fantastic sounds - I guess my dream machine will always be a teletype machine - kind of big and not necessarily that cheap, but definitely the ultimate soundtrack for me.
A very handsome calculator, the design is very elegant. Just the right amount of curves and in right places. Thanks for sharing.
I fell in love with the look of this machine when I first saw a picture of one (I think it was the 610 that I saw, which doesn't have the memory keys but is otherwise identical), as you say, just the right amount of curves. Cheers for watching and commenting.
Great video. Back at school in the 80s, our science teacher was clearing out her store cupboard and found a couple of Numicator calculators. I loved the clicking of the relays when the digits changed.
Hi John - I love anything like that - especially the sound of clicking relays and the like - I've seen videos where people have made themselves relay computers - I'd quite fancy doing that but it would take time, and would probably be far from cheap! Maybe one day....
While I think of it John, in case I'd misled you into thinking my machine has relays - when I did the count down at the end of the video, I simply entered 20, then pressed 1, shortly followed by the minus equals key and repeated that at about 1 second intervals to give the impression the machine was counting down - I didn't intend to include the sound, but it actually sounded so mechanical that I left that channel unmuted. So the sound you can hear is just me tapping at the keyboard.
@@GrumpyTim lol I hadn’t noticed the sound tbh. No, the calculators we found at school had lovely clicky relays when the figures changed. Made it sound like the thing was doing some work!
I thought that was what you meant, then suddenly I thought you might have been meaning the sound of my calc!!! Those machines at your school must have been so cool - I'd love to get one of those, but I'd be willing to bet, unless I got very lucky, that I'd never find one, or certainly one I could afford. I watched one of the early Anita machines sell for something like £2000 on ebay last year - I had a very early bid on that machine but it soon became obvious I was nowhere near so I sat back and watched!!!
@@GrumpyTim I bought 5,000 relays from a scrapyard. I believe they are 5 V.
Well done on getting this machine to work again! I too love the look of Nixie tubes, but don’t have any.
Cheers Jaap, it's been a multiple year wait to finally get a machine with a Nixie tube display - I'm sure they must come up cheaply or even free at times, but never when I've been looking. Definitely worth the wait.
I have one of these. I was lucky enough for it to be in working order, all for £3.20. It fell through the cracks on eBay because the magic “Nixie” word was missing from the listing. The chap I collected it from was happy it was going to a good home, and sold me another Monroe (Model 430) with a Panaplex display for £5. Well worth the 150 mile round trip!
Good heavens, that was a good day out!!!! I never get that lucky. I've had a couple of machines that I bought, or at least thought I'd bought on ebay, but both had been thrown out during a clear out of the garage and the sellers forgot to remove the listings, so there must still be plenty going for scrap - just need to figure out a way of intercepting them.......
Good repair on the electronics and outstanding repair on the plastic! Well done!
Cheers Ben, I could, and probably still will, do a bit more work on the plastic, but not so much that it detracts from the originality of the unit, definitely not going to be respraying the whole thing!!! One thing I didn't point out in the video because it would have been difficult to show, was that there are two dents in the front edge of the calculator - not from an impact, but from where the user rested their fingers for many years - that thing must have seen so many hours of use during it's lifetime. The pimple on the number 5 is also more or less worn out too.
@@GrumpyTim That's quite an impressive mileage!
Great video as usual but most all thanks for the reference to The Art of Making a Nixie Tube. That guy and his work is amazing! I love your channel.
Thanks Scott, glad you enjoyed the video from Dalibor Farny - I love watching how he makes the tubes - every step of the process is interesting.
Hi Scott, I hadn't checked my emails when I replied earlier, thanks so much for the donation, that'll help getting components for the next machine - it arrived today, and it's a bit of a daunting task on first glance!!! There might be a few videos on other topics before I start the next calculator repair, but it'll be along fairly soon.....
@@GrumpyTim Anytime. I wish I could give more I love all your videos. I love watching you repair and restore calculators and typewriters. Keep it up please.
Will do Scott, there's plenty more in the pipeline to come soon.
At this point I'm fairly confident that you're a wizard or possibly a mad scientist and at some point you're gonna figure out faster than light travel.
I always love watching you take these things apart and repair them despite not having a clue what any of it means.
Oh and Nixie Tubes is incredibly fun to say and would be a great name for a band!
Have a good one, mate🖖
I've always wanted to be a mad scientist David, but in reality I'm just tinkering with stuff that some previous mad scientist invented - still it's fun even if I'm not actually inventing the stuff myself. Hmmmm the Nixie Tubes would have been a fantastic band name - I wonder if anyone ever used the name, even some more or less unheard of band. I've got an even earlier calculator to work on now - progress was fast at that time, so going back 3 years makes a lot of difference, and it smells of the 1960s too.........
Cheers for watching
@@GrumpyTim Yeah looking at how fast things changed between the 60’s and say the 80’s is bonkers. Looking forward to seeing that video, Tim🖖
All I need now is an early 60s electronic calculator, but the last one I saw sell on ebay went for about 2 grand, so I won't be getting one of those any time ever!!!! They had the most bonkers mad science components inside - maybe I'll find one in a skip one day......
They're mesmerizing.
I'd quite like to get hold of a bit of old test equipment of some kind that has a nixie tube display - that would just be cool, and potentially useful depending on what it tested!!!
Great job, and congratulations to your successful bid on Ebay for one of those "holy grale" nixie calculators 😊. Wonderful close-up shots of the nixie tubes! I always enjoy that 3D factor of these displays where the digits are jumping back and forth.
To my point of view, you are completely right not to respray the case to make it perfect. By the way, this calculator has a wonderful 70th design.
You know the weird thing, I've been waiting for 3 years or so to get a Nixie calculator, and within one month I've got another one - no idea if the latest one will work or not, but I'll check it thoroughly before applying power. The new addition pre dates the Monroe by about 3 years, so instead of 4 chips, there are about 40. It's not visually as attractive as the Monroe, which, as you say, is a great 1970s design. Glad you approve of my decision not to respray - I rather like originality, even if it's a bit shabby here and there.
@GrumpyTim Wow, I'm looking forward to the video where you will reveal the machine. I have Soemtron ETR 220 from 1972 in my collection, which was produced in the GDR and has no chips at all.
It only has discrete transistors and diodes and a core memory. It's bigger than most of my mechanical calculators...
Wow, your Soemtron must be a fantastic beast of a machine, what a brilliant machine to have in your collection - I've just looked up some photos. I've found with a few of my early electronic machines, that they're somewhat bigger than they looked in the photos - I can only imagine how massive the Soemtron is!!!
Interesting to see it has a Canon motherboard
Hi ohjajohh, it appears to have been quite common at that time - calculators were developing so fast that some established brands like Monroe and Friden, bought machines from Japanese manufacturers and put their own name on them. I guess it's a bit like that with many cars these days - like the Toyota Aygo is also sold as the Citroen C1 and the Peugeot 107 - it just costs so much to develop a new car these days that many manufacturers do these joint projects.
I have just purchased one of these without the power. I'd be very very VERY greatful if you'd consider printing one of your connectors for me & popping it on Ebay or something? As I'd love to be able to test this unit. Cheers Tim.
Hi RenaissanceManChild, if you want to send me an email (address somewhere in the "About" tab for my channel) I'll see if I can print one sometime - I should still have the design lurking on my computer somewhere.
🔥👍
Thanks capy-bite - oooh it looks like you have some nice stuff on your channel, I'll take a proper look later on.
I got it without nixie tubes, do you want it? Just let me know :)
Thanks for the offer Pawel but I'm probably ok with just the one of these. I your machine one that someone has removed the nixie tubes for other projects?
@@GrumpyTim Yes, niexies removed. If you could set up the shiping from Poland i could give it for free...
Thanks for the kind offer Pawel, but I'm rapidly running out of space so I really need to stop adding machines to the collection!!!
@@GrumpyTim You cannot even imagine how I can relate to this :P Wives huh?! :P
I think there are two types of people - ones who have pristine houses with nothing in them, and people who like collecting stuff - I know which one I am!!!!