Years ago, I had a T.I. Calculator that had a very similar display and worked with both batteries or a power supply much like the one you have here. Wow, lots of memories. I got a lot of years worth of use from that calculator and it still works !!
The year was 1976 and 1977 for me and my electronics class and this calculator was the best! In later years I too made a power supply for it. With 1.1 in both memories and the display it used a few hundred milliamps. With -8888888888.88 in both memories and the display it pulled a whopping 800 milliamps. Even in school the battery never lasted more than a couple hours even when it was new. I did not care. It is an awesome calculator.
Thanks! I never spent any longer period of time in an English speaking country. All the English I know is from RUclips videos. ;) (Joking aside, I actually studied English Literature at uni for a couple of years, I guess that helped a bit.)
@JanBeta I lived in Germany for 5 years as a child and my German was OK, but over the years it has faded away, I can understand some but have lost the ability to talk in it. A lot of your off the cuf comments are perfect which is why I thought you must have spent some time around English-speaking people.
From the 1970s calculator wars, that were about the first mass-produced electronic gadget. In order to raise profits in a linear fashion (or even just stay in business) the company has to produce exponentially more calculators over time. The business works like this to this day.
At one time, many years ago, I had a Commodore 64 that I just loved ! One thing I found it very very useful for was it's ability to act as a very large calculator. I just turned it on and typed in whatever formula I was working on and I always got the correct answer. I also liked being able to change how many digits the answer could be changed to for accuracy.
Yes, I thought about that. Did some successful polishing on plastics a while back. The scratch is pretty minor, it looks way worse on camera than it does in actual use but I still might try to polish it out sometime.
To remove marks and scratches on plastic screens Displex display polish is very good, if a bit on the expensive side. Here in the UK it’s around £8 on eBay / Amazon for a small tube but you don’t need to use very much of it.
Yes, I've done some successful polishing of clear plastics a while back (there's even a couple of videos about it on the channel). I might go back and try it sometime on the display. The scratch is super minor (looks way worse on camera than during actual use) so maybe not worth risking more damage. We'll see.
GL-997R, the calculator that sits on my desk since 2 decades now. A bit newer than yours and less functions. But I love it, especially the green display.
@@JanBeta yeah, works great until today. the VFD is still bright and very evenly illuminated. Even the few caps are still good. I checked them years back, but all were fine. So I wanted to keep them original as long as possible. What's really surprising is the reliability of the plastic and paint. The calculator is always on my desks, sun is hitting it. Nothing brittle or worn out. Close an age of 50 and still going 🙂
For the scratches on the display Brasso in the can works great. A little pinch of that would probably get rid of the scratches completely. Learned that one from tech moan. Used that method on a horribly scratched turntable lid and it eliminated all but the deepest ones
@@JanBeta I used to make my own mirror finish stainless steel rings in Jr high by hand. Decidedly harder material. My first job out of high school was polishing stainless plates and sheets, etc. So I know what surface quality is about. With the bezel removed and held by the fingers you could likely buff that out on your knee in a pair of jeans.
This "step-up converter" is definitely needed to provide negative voltage - on the PCB close to the edges you find labelled voltage rails VSS (positive) and VGG (negative). The circuit looks like typical negative voltage generator designed around PNP-NPN transistors/two diodes/two capacitors judging by the components and PCB layout in my CBM. It would be great to reverse engineer and know the diagram for the learning - for me difficulty is the toroid transformer. There are 5 pins coming from it, all windings are connected, not sure what it does.
I've also always used permanent marker for touch-up. Now I'm wondering if black nail polish would be better? Will have to give it a try next time I need to touch up a metal surface.
To get the display back into its shiny glory and remove the scratches left by the button, I recommend using masking tape (so as not to polish the rest of the case), some PolyWatch, and lots of patience.
Bit of Peek polish (or similar) ought to get that mark polished out from the display lens, it's quite good at making scratches and scuffs disappear from shiny plastics like that... :D
@@AB0BA_69 It is indeed a fine abrasive, but it's called a polish for a reason, I've used it to polish up scuffed and scraped plastics nicely, there's also Novus polishing kits, but that's quite an expense for such a small project...
@@twocvbloke The trouble with these polishes is that they don't guarantee to completely hide the blemish. Since you are removing material (and some was already removed by scratches) you are not guaranteed to get the same finish. This is a consumer device and not some priceless art piece so it won't be a total disaster but IMO sometimes "less is more", you know?
Yes, I think so. I've had some very good results on clear plastics with polishing paste a while back. I might try it sometime, although the scratch is very minor and looks worse on camera than in real life on this one.
Of course, another workaround for the case scratching the display would be to turn the calculator around in the case, either front-to-back or top-to-bottom.
I am confident that you are right: these early calculator chips used a PMOS process that required a negative bias. The Commodore PR100 I have here for example has a similar inverter that gives about -4V. Black is ground, red is switched approx 4V Vbat, and blue is the approx -4V output. Depending on the process, the PMOS threshold voltage may require a larger negative bias, it was not uncommon for a -12V rail to to be required back in the day.
What amazes me is how a calculator can add, subtract, multiply, divide and much more with 12 digit floating point numbers. Whoever programmed this is a genius. 🙂👍
Yes! It was very cutting edge technology at the time. Amazing feat to integrate all of the math operations in a single chip. And it still works, too! :D
I bought some of those felt pads years ago - now and then I used to randomly stick them to my wife in her sleep for her to discover later on in the day, she loved it ... 😮💨 heheh.
You could of course easily mod this to power it via USB. Then you could power it with the computer or a USB docking station and keep it on the desk without using an extra mains socket. I know you want to keep it mostly original, but it's an option for these old mains powered calculators.
I tried running the calculator from 5V via my bench supply but it didn't suffice to start it up. Would need a bit of tinkering and changing the original circuit to make it work with an old school USB adapter unfortunately. Or a voltage converter and USB-C. I might look into that.
Jetzt brauchst Du nur noch eine Commodore Schreibmaschine und die Sammlung ist komplett. Obwohl die Reparatur dann vielleicht nicht Deine Stärke wäre?😄
Ich hatte schon ein paar mal eine auf der eBay-Beobachtungsliste, habe mich dann aber dagegen entschieden. Mechanik ist nicht so wirklich meine Stärke. Aber wahrscheinlich kann ich irgendwann nicht mehr widerstehen. :D
I thought about that but decided against it for now. The plug being loose on the original power supply is not very safe. Might go in and give it a try sometime though.
With annoying cables like that that keep going back the that shape where it's been cabled tied, I soak the cable briefly in hot water from a kettle and then stretch it out until cool.
Hi Jan, I just finished a package for you today and will ship it tomorrow (hope your address is still the same). It contains a device frorm the same era. I won't tell you what it is, but i'm sure you will like it and I hope that you will make it the subject of another video.
Commodore Business Machines is what it stands for. They used to make typewriters, office furniture and mechanical adding machines before they went electronic. :)
You should have used the old case of the old power supply and moved the board from the new to the old one. Changing the plug on a new power supply ruin the whole thing.
I thought about that but decided against it for now. Mostly because the original plug was so loose and it poses a bit of a risk. I might still tinker with that at some point though.
500,000 years from now, our descendants will find this Commodore in the clutches of Jan Beta's bones and they'll ponder it's ceremonial significance.
:D
Years ago, I had a T.I. Calculator that had a very similar display and worked with both batteries or a power supply much like the one you have here. Wow, lots of memories. I got a lot of years worth of use from that calculator and it still works !!
It's so cool that these old gadgets still work these days. Who would have thought? :D
What awful person would ever give rude comments to this amazing RUclipsr?
Haha, thanks. It actually happens very rarely but I guess it can't be avoided completely. This is RUclips, after all. :D
The year was 1976 and 1977 for me and my electronics class and this calculator was the best! In later years I too made a power supply for it. With 1.1 in both memories and the display it used a few hundred milliamps. With -8888888888.88 in both memories and the display it pulled a whopping 800 milliamps. Even in school the battery never lasted more than a couple hours even when it was new. I did not care. It is an awesome calculator.
Good job with the felt pad and marker pen Jan. My OCD is now truly covered.
Excellent! :D
No rude comments here. Thanks, Jan!
Thank you!
Nice Video. Looking at the calculator is like going back in time - Happy days !
Your English is so perfect, you must have spent a very long time in an English speaking country. Love your videos 😊
Thanks! I never spent any longer period of time in an English speaking country. All the English I know is from RUclips videos. ;) (Joking aside, I actually studied English Literature at uni for a couple of years, I guess that helped a bit.)
@JanBeta I lived in Germany for 5 years as a child and my German was OK, but over the years it has faded away, I can understand some but have lost the ability to talk in it.
A lot of your off the cuf comments are perfect which is why I thought you must have spent some time around English-speaking people.
From the 1970s calculator wars, that were about the first mass-produced electronic gadget. In order to raise profits in a linear fashion (or even just stay in business) the company has to produce exponentially more calculators over time. The business works like this to this day.
Your videos are always very interesting!
Thanks Sayaka! Love your videos, too! So cool to see some younger peeps enjoying the old tech still! :)
At one time, many years ago, I had a Commodore 64 that I just loved ! One thing I found it very very useful for was it's ability to act as a very large calculator. I just turned it on and typed in whatever formula I was working on and I always got the correct answer. I also liked being able to change how many digits the answer could be changed to for accuracy.
I did the same with my C64! I had a (boring) LCD calculator a bit later but the C64 was running most of the time anyway, so I often used that. :)
Your videos are always interesting.
Thanks! :D
You can remove the marks on the display glass by using a polish creme used for car lights. Done that to some other modern calculators, works fine.
Yes, I thought about that. Did some successful polishing on plastics a while back. The scratch is pretty minor, it looks way worse on camera than it does in actual use but I still might try to polish it out sometime.
@@JanBeta That bezel can be removed easily to do the job without the mount getting abraded or "polished" with it.
Gotta love that LED display.
It is absolutely magnificent. :)
To remove marks and scratches on plastic screens Displex display polish is very good, if a bit on the expensive side. Here in the UK it’s around £8 on eBay / Amazon for a small tube but you don’t need to use very much of it.
Yes, I've done some successful polishing of clear plastics a while back (there's even a couple of videos about it on the channel). I might go back and try it sometime on the display. The scratch is super minor (looks way worse on camera than during actual use) so maybe not worth risking more damage. We'll see.
GL-997R, the calculator that sits on my desk since 2 decades now. A bit newer than yours and less functions. But I love it, especially the green display.
Just looked that one up, looks really nice as well! It's kind of amazing that these old calculators still work at all these days. :D
@@JanBeta yeah, works great until today. the VFD is still bright and very evenly illuminated. Even the few caps are still good. I checked them years back, but all were fine. So I wanted to keep them original as long as possible.
What's really surprising is the reliability of the plastic and paint. The calculator is always on my desks, sun is hitting it. Nothing brittle or worn out. Close an age of 50 and still going 🙂
For the scratches on the display Brasso in the can works great. A little pinch of that would probably get rid of the scratches completely. Learned that one from tech moan. Used that method on a horribly scratched turntable lid and it eliminated all but the deepest ones
Yep, I consider trying that. I made some videos about polishing clear plastics a while back (coincidentally, also a turntable lid). :D
@@JanBeta I used to make my own mirror finish stainless steel rings in Jr high by hand. Decidedly harder material. My first job out of high school was polishing stainless plates and sheets, etc. So I know what surface quality is about. With the bezel removed and held by the fingers you could likely buff that out on your knee in a pair of jeans.
This "step-up converter" is definitely needed to provide negative voltage - on the PCB close to the edges you find labelled voltage rails VSS (positive) and VGG (negative). The circuit looks like typical negative voltage generator designed around PNP-NPN transistors/two diodes/two capacitors judging by the components and PCB layout in my CBM. It would be great to reverse engineer and know the diagram for the learning - for me difficulty is the toroid transformer. There are 5 pins coming from it, all windings are connected, not sure what it does.
I've also always used permanent marker for touch-up. Now I'm wondering if black nail polish would be better? Will have to give it a try next time I need to touch up a metal surface.
I have yet to try that myself. I guess it depends on what you are touching up. :)
To get the display back into its shiny glory and remove the scratches left by the button, I recommend using masking tape (so as not to polish the rest of the case), some PolyWatch, and lots of patience.
Bit of Peek polish (or similar) ought to get that mark polished out from the display lens, it's quite good at making scratches and scuffs disappear from shiny plastics like that... :D
Is that just a very fine abrasive?
If so, then IMO it would not be worth it for such a small imperfection because of a chance of making things worse
@@AB0BA_69 It is indeed a fine abrasive, but it's called a polish for a reason, I've used it to polish up scuffed and scraped plastics nicely, there's also Novus polishing kits, but that's quite an expense for such a small project...
Yep, I consider trying that at some point. I had some great results with a product meant for car headlights a while back. :)
@@twocvbloke The trouble with these polishes is that they don't guarantee to completely hide the blemish. Since you are removing material (and some was already removed by scratches) you are not guaranteed to get the same finish.
This is a consumer device and not some priceless art piece so it won't be a total disaster but IMO sometimes "less is more", you know?
love your work - interesting as always - maybe you can build an USB to 6V converter to use it while working on the pc or notebook
keep going
Michael
Thank you! A USB converter would be handy indeed. I might look into that. :)
I wonder if something like polywatch might be able to repair that display and take the scratches out.
Yes, I think so. I've had some very good results on clear plastics with polishing paste a while back. I might try it sometime, although the scratch is very minor and looks worse on camera than in real life on this one.
Just a man and his Commodore calculator 😊❤
I love this thing! :D
Great video Jan 👍 what’s in the red box in the background ?🤔
That's where the heat shrink tubing came from. It's an old shoe box I store electrical tape, heat shrink and similar stuff in. :)
Awesome calculator.
It is absolutely lovely!
Of course, another workaround for the case scratching the display would be to turn the calculator around in the case, either front-to-back or top-to-bottom.
Yep, that would be an easy "fix". :D Didn't think of that.
Hi,
it cannot be ruled out that that circuit can be used to generate a negative voltage. You could have checked what voltage is on the blue wire.
Oh, I'm going to have a look.
I am confident that you are right: these early calculator chips used a PMOS process that required a negative bias. The Commodore PR100 I have here for example has a similar inverter that gives about -4V. Black is ground, red is switched approx 4V Vbat, and blue is the approx -4V output.
Depending on the process, the PMOS threshold voltage may require a larger negative bias, it was not uncommon for a -12V rail to to be required back in the day.
What amazes me is how a calculator can add, subtract, multiply, divide and much more with 12 digit floating point numbers. Whoever programmed this is a genius.
🙂👍
Yes! It was very cutting edge technology at the time. Amazing feat to integrate all of the math operations in a single chip. And it still works, too! :D
I bought some of those felt pads years ago - now and then I used to randomly stick them to my wife in her sleep for her to discover later on in the day, she loved it ... 😮💨 heheh.
You could of course easily mod this to power it via USB. Then you could power it with the computer or a USB docking station and keep it on the desk without using an extra mains socket. I know you want to keep it mostly original, but it's an option for these old mains powered calculators.
I tried running the calculator from 5V via my bench supply but it didn't suffice to start it up. Would need a bit of tinkering and changing the original circuit to make it work with an old school USB adapter unfortunately. Or a voltage converter and USB-C. I might look into that.
Jetzt brauchst Du nur noch eine Commodore Schreibmaschine und die Sammlung ist komplett. Obwohl die Reparatur dann vielleicht nicht Deine Stärke wäre?😄
Ich hatte schon ein paar mal eine auf der eBay-Beobachtungsliste, habe mich dann aber dagegen entschieden. Mechanik ist nicht so wirklich meine Stärke. Aber wahrscheinlich kann ich irgendwann nicht mehr widerstehen. :D
I would have stuffed the guts of the modern power supply into the original power supply case.
I thought about that but decided against it for now. The plug being loose on the original power supply is not very safe. Might go in and give it a try sometime though.
With annoying cables like that that keep going back the that shape where it's been cabled tied, I soak the cable briefly in hot water from a kettle and then stretch it out until cool.
Ah, thanks! I am going to give that a try. :D
The AC⚡DC adapter, for those about to calc.
WE compute you!
Let there be math!
@@JanBeta 'Cause I'm the Tax Man...
Hi Jan, I just finished a package for you today and will ship it tomorrow (hope your address is still the same). It contains a device frorm the same era. I won't tell you what it is, but i'm sure you will like it and I hope that you will make it the subject of another video.
Hey, awesome, thanks! Looking forward to the surprise. The address is still the same, I'm not moving anytime soon. :D
Other workaround for scratching the display is to simply put the calculator in the pouch backwards.
You can hate me now! 😊
Haha, yeah, I didn't think of that. But then again, right side up is quicker to get out and calculate. :D
cbm? That can't be Commodore, because i got one without the Commodore logo.
Commodore Business Machines is what it stands for. They used to make typewriters, office furniture and mechanical adding machines before they went electronic. :)
@12:07 that would be me, how I wished I never took it back for a refund.
I see! Thanks for pointing that out. Sorry that I didn't remember to note down your name! RUclips comments are difficult to browse. :D
@@JanBeta just happy for the mention and hoping one day someone else says I had one too!
You should have used the old case of the old power supply and moved the board from the new to the old one. Changing the plug on a new power supply ruin the whole thing.
I thought about that but decided against it for now. Mostly because the original plug was so loose and it poses a bit of a risk. I might still tinker with that at some point though.
Turn the calculator the other way so the bottom is turned against you and it will not scratch the screen any more.
Schon wieder nicht erster 🤣🤣🤣
Tsss, du wirst aber auch immer langsamer, Sven! ;P