Canon S-51 typewriter (SMK "peerless"?)


28 Sep 2018, 19:45

I found a cheap-looking electronic typewriter at a flea market for €5. The keycaps were nice though and I liked the key feel so I bought it without looking further. And when I got home, I took it apart ...

CanonS-51.jpg (403.15 KiB) Viewed 10436 times
We have seen other other Canon typewriters, but with Alps stems and switches. This keyboard however, has two other types of switches that I have not seen before. Also, the keycaps are cylindrical, not spherical... except for the ones on either side of the space bar which are flat.

The full-size keys have a discrete integrated slider-over-spring-over-conductive rubber dome-over-PCB switch, whereas I think the smaller buttons are merely discrete integrated domes.

CanonS-51_PCB.jpg (832.32 KiB) Viewed 10436 times
CanonS-51_PCB_back.jpg (491.64 KiB) Viewed 10436 times
Apparently, this keyboard was made by SMK. And like some verified SMK switches, these switch modules have no markings other than a digit or letter, probably indicating position in the injection-mould parts tree.

The LCD screen 's PCB is attached to the top of the plate, with passthrough to the keyboard PCB which has a ribbon cable to the typewriter's main PCB.
CanonS-51_modules.jpg (588.66 KiB) Viewed 10436 times
In each switch's bottom, there is a dome, and ...

Large switch
CanonS-51_key_off.jpg (374.51 KiB) Viewed 10436 times
... inside the top of a larger switch module, I can just see that there is a coiled spring in there.
I have not found a way to take these modules apart, yet ...

The large switches are light and clicky, with a very light sound that got louder after I had unscrewed the PCB-plate assembly. The switches feel linear up to the click point at which resistance drops off and the dome inside juts forward.
So, this is most likely similar to the Fujitsu Peerless mechanism — but I would dare say, better, as these are light and stable. No key felt the least scratchy on a off-centre key press but then I got this in good condition.

With my measly calipers I measured total key travel at 4 mm and (slow) travel to actuation to ~2.5 mm.
I do suspect that (as Peerless switches), the actuation distance could vary with typing speed.
They bottom out soft and distinct, like good rubber domes (such as Topre, BTC etc).
CanonS-51_stab.jpg (63.64 KiB) Viewed 10436 times
The stabilisers are nice too. Hinged inside the keycap and the clips in the plate have ramps that guide the stabiliser wire into the right position when you install it. A much better solution than Costar-style or Alps stabilisers IMHO.

Small switch
CanonS-51_small_dome.jpg (82.11 KiB) Viewed 10436 times
CanonS-51_CODE.jpg (61.03 KiB) Viewed 10436 times
The smaller switch has a slider that covers the top of the switch: the entire top presses down and only a short amount.
The mount is not Cherry MX-compatible BTW. These can also have stabilisers.

Anyone seen these before? I quite like the larger switches. Clicky but quiet.
Last edited by Findecanor on 28 Sep 2018, 22:10, edited 1 time in total.


28 Sep 2018, 20:19

I actually found a few of these among a collection of random NOS switches I picked up a few months ago. I have several of the bar mount integrated dome version. I have one of the cruciform mount, but my instance has a cutout in one corner that I assume is for an LED.
switches-47.jpg (2.86 MiB) Viewed 10420 times

They are interesting switches, but like most rubber domes all the action happens very close to bottom out.
They all appear to using a conductive pad for activation. Does the PCB on your board confirm this?

Edit: The cruciform one only seems to have about 2mm of total travel.


28 Sep 2018, 21:59

Cool. Do you have any lead from your purchase back to any manufacturer?

Yes, the swirly gold pads on the PCB in the image are each two terminals shorted by the conductive pad on the bottom of the dome when pressed.

The cruciform-mount switch has very low key travel, yes. I'm sorry I forgot to mention that. Also, the buttons on those "keys" are much lower than regular keys to start with. The circle is a dial on the display's board, which I think adjusts contrast.
I have not actually fired up the typewriter, because it was missing a power supply. It does take batteries though, but I don't have any that large... have not used for years. :-þ


28 Sep 2018, 22:22

Findecanor wrote: Cool. Do you have any lead from your purchase back to any manufacturer?
Unfortunately, no. The lot of switches had examples from several different manufacturers.

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28 Sep 2018, 23:36

I actually just picked up a Cannon Typestar 6 (S-60) and was about to start a thread about it, but here we are! It uses the same switches with the same caps but has an additional small text button to the left of the mode button. The switches are pretty nice to type on and they sound pretty nice as well. It is certainly a nice find.

EDIT: Mine also has some spanish characters (Ñ ¿ ¡) which yours does not have, but this is probably not related to the model difference.
Last edited by zrrion on 29 Sep 2018, 00:03, edited 1 time in total.


28 Sep 2018, 23:58

Apparently the S-51's keyboard has the pad for the S-60's "Text" button. Maybe they have the same PCB, unless the S-60's bigger display's PCB needs more pins.
Please do post your pics. I have only crappy cameras.

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01 Oct 2018, 09:49

Anyone looking for Alps-compatible keycaps on Canon typewriters just have to look for the centred lock light on the caps-lock, worked like a charm for me when rummaging through ads on my "craigslist". :)


27 Feb 2019, 21:37

Sendrim over at Mekaniska Tangentbord Sverige recently got a Canon S-80 which looks 99%identical to mine above, but it dual spring-over-membrane switches — those commonly called "Amstrad switches".

So.. three different types of switches identified so far:
• Alps
• SMK spring-over-dome
• Amstrad


05 May 2019, 21:04

I've just acquired one of these typewriters, and rather incompetently demoed it on video if you want to see it in action:

I really like the keyboard, and am rather interested in converting it to USB and using it as a PC keyboard (I'm not allowed to use my Model M at work). The only problem is there aren't quite enough keys for an ISO layout and so I'd either need a custom keymap or acquire another one and somehow cobble together a expanded keyboard. A custom PCB, maybe?


06 May 2019, 18:59

Why aren't you allowed to use a Model M at work?
Who would forbid that? Did anyone complained about them being too noisy? :)


09 May 2019, 15:13

Yup, just too loud. I kinda quite like my cow orkers.

Turns out that a number of these old typewriter keyboards are really good complex rubber dome mechanisms --- the Brother keyboards are apparently very reminiscent of modern Topre, so I'm going to try and retrofit one.


04 Nov 2019, 21:08

I know this is verging on a necropost, but this is directly related to a previous post: I have finished converting the typewriter to USB. There's lots of stuff including video of the whole sordid business here.

I'm pretty sure the keyswitches are SMK spring-over-dome. Spotting the bit in one of my videos where I noticed the large SMK logo on the PCB, which I subsequently forgot about seeing, really helped. wiki/SMK_spring_over_dome

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