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Old 11th Dec 2022, 7:16 pm   #1
ScottishColin
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Default Help with power cable for a Casio R-1 calculator

I've retrieved this rather wonderful old calculator (last PAT tested in 1978) from my Dad's but it does not have a power cable.

I have rather a lot of power cables but not one like this - does anyone recognise it and if so could you point me at a lead to go and buy?

Thanks.

Colin.
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Old 11th Dec 2022, 7:27 pm   #2
factory
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Default Re: Help with power cable for a Casio R-1 calculator

I've also got a Casio calculator without the lead, unfortunately they are too expensive, might have to replace it with something modern.
Only one I've seen for sale can be found on ebay; https://www.ebay.co.uk/itm/193915295938

David
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Old 11th Dec 2022, 7:32 pm   #3
ScottishColin
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Default Re: Help with power cable for a Casio R-1 calculator

Thanks. But crikey, that's a little more expensive than I thought it might be....

Colin.
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Old 11th Dec 2022, 7:38 pm   #4
factory
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Default Re: Help with power cable for a Casio R-1 calculator

Probably why it's been advertised for almost two years, but hopefully the pictures will help people identify the lead.

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Old 11th Dec 2022, 7:43 pm   #5
Paul_RK
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Default Re: Help with power cable for a Casio R-1 calculator

I thought my Casio fX-1 from 1972 used the same connector, but I'm wrong, it employs a standard IEC type. A little Addmaster Merlin 8K, on the other hand, does look to have the right cable, but can't nicely be deprived of it. Must be a good chance of one lingering in somebody's spares box.

Paul
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Old 16th Dec 2022, 5:13 pm   #6
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Default Re: Help with power cable for a Casio R-1 calculator

The tape measure suggests that it's around the same footprint as an IEC C14 "kettle" type, the fixing centres may even be similar. I realise that fitting non-original connectors counts as a cardinal sin to some, but at least the C13/14 combo is universal, inexpensive and approved.
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Old 28th Dec 2022, 2:41 pm   #7
ScottishColin
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Default Re: Help with power cable for a Casio R-1 calculator

Hi all - I've replaced the connector with a normal kettle connector and after having a good clean up and inspection, I've powered it on and it powers up and prints when I use the keyboard so I'm off to a good start; there's even a small amount of ink left in the ribbon surprisingly.

The problem now is that the paper motor does not work so the paper does not advance when using the calculator, nor when I press the Feed button. On further inspection, the ribbon does not move either which I assume it should do.

I'm guessing I'm going to be moving on to taking lots of photos and stripping the calculator down.

Has anyone ever worked on anything like this before? I can find no manuals or schematics anywhere on the internet; the University of Stuttgart Computer Museum has one and I have emailed them to see if they can help.

http://computermuseum.informatik.uni...v_en/casio_r1/

Thanks in advance.

Colin.
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Old 28th Dec 2022, 6:22 pm   #8
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Default Re: Help with power cable for a Casio R-1 calculator

I've never worked on one of those but I have worked on old Casio desktop calculators. And on printing calculators.

The fact that it basically works when you press keys is a good sign, it means most of the logic is working and that probably the custom LSI chips are good. So you have some hope of fixing it.

How should the printer work? A lot of printing calculators of that period used a drum type pronter. A rotating drum with the digits round it in rings going across the whole width of the paper, And a print hammer for each column which is fired at the appropriate time to print the right digit in that column. There is normally only one motor, it drives the drum, to advance the paper, a solenoid engages a lever with a cam on the drum sprindle which operates a ratchet to advance the paper. The ribbon advance is normally operated by the same mechanism.

So, if it is like that, it might be a mechanical problem (levers stuck in hardened grease), the operating solenoid, the solenpid driver, or worst of all the logic that controls it.
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Old 29th Dec 2022, 12:21 pm   #9
ScottishColin
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Default Re: Help with power cable for a Casio R-1 calculator

Thanks Tony. It is a drum printer.

I'll start by taking lots of photos so I know how to put it back together and then take it apart carefully.

I have had an email reply from the University of Stuttgart; they don't have any manuals but they are going to dig their R-1 out of storage to take a look. They have also suggested grease may be the problem.

If it's grease, I guess it's a matter of digging it all out and replacing it with something? Or would some kind of silicone spray do the job?

Colin.
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Old 29th Dec 2022, 4:51 pm   #10
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Default Re: Help with power cable for a Casio R-1 calculator

I often find that photos are pretty useless for something like this in that they don't show what you really need to know.

In particular there will be a timing sensor for the drum rotation, it may look like a tape head. The gap between this and the spinning bit that triggers it is critical, measure it with a feeler guage if you dismantle anything in this area. Also the angular position of the timing trigger 'spinnging bit' to the drum is crtical, get it wrong and it won't print the correct numbers or print evenly.

There may also be crtical timings between the gears in a gear train, if in doubt scratch marks on meshing teeth before you take it apart so you can get it back right.

And after putting it back together, turn it by hand, not the motor to check it can run. I found out the hard way that if you get something wrong the whole mechanism can lock up, And the motor can have enough torque to strip plastic gears or break toothed drive belts.

But before doing anything much :

You'll almost certainly find that the printer unit comes out as a separate module. Post a photo of it out of the calculator. I might recognise it. I might even have some information on it.
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Old 29th Dec 2022, 5:04 pm   #11
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Default Re: Help with power cable for a Casio R-1 calculator

Interesting! Having recently done a project involving significant dismantling, sketches and desoldering before discovering the problem was purely mechanical alignment that could have been fixed with the removal of three screws, I'd agree with TonyDuell that grease and the like can have significant impacts!

I'd check continuity of the 'feed' button circuit etc. I suppose the motor should be running and isn't, and it could be as simple as a failed power rail capacitor or dirty contact. I hope it's something similar and you can fix it before getting into marking meshing gears and timing sensors - that sounds scary!
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Old 30th Dec 2022, 11:03 pm   #12
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Default Re: Help with power cable for a Casio R-1 calculator

Just to let you all know the calculator now works fine and the printer advances the paper and the ribbon.

I took it all apart (the photos were so I knew how to put it back together again) and everything moved fine manually and I could manually get the printer rollers to advance by pushing a lever.

I then took a look at the solenoid and cleaned it up and tested it and all is now well.

I attach a couple of photos for anyone's interest - I would like to know if the areas of metal the solenoid moves are both supposed to have what looks like copper on them? Only one does and I'm just wondering if I should fashion some kind of replacement for the other one? Or is it fine how it is?

And if anyone has any idea where to get a two coloured ribbon from for this calculator, I'd be grateful.

Thanks all.

Colin.
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Old 30th Dec 2022, 11:14 pm   #13
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Default Re: Help with power cable for a Casio R-1 calculator

That's excellent it was straightforward, Colin!

If it works, I'd be tempted not to fix it until it's broken, but beyond that can't offer advice on the solenoid.

I can say that two (or more) coloured ribbon is widely available. If it's a typewriter-type ribbon you need rather than a proprietary cartridge. Check the diameter of the reel spindles and the width of the ribbon if it's a discrete type, and try George Blackman , Charlie Foxtrot, or Globe Typewriters on eBay. I've bought ribbons from them all, and the last one was able to supply me with a peculiar 8mm ribbon for a watch timing machine.
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Old 2nd Jan 2023, 4:10 pm   #14
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Default Re: Help with power cable for a Casio R-1 calculator

Quote:
Originally Posted by ScottishColin View Post
I've retrieved this rather wonderful old calculator (last PAT tested in 1978) from my Dad's but it does not have a power cable.

I have rather a lot of power cables but not one like this - does anyone recognise it and if so could you point me at a lead to go and buy?

Thanks.

Colin.
I've taken many of these old calculators apart over the years, the ones which were most common were the Olivetti machines which I noticed always had similar leads and pin arrangement... although the corners of the Olivetti lead plugs are always mostly round (elongated), I still think that they would/might fit into your Casio calculator's rectangle plug hole... might be worth a try if you could find one cheap enough... Good luck
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