PTT Telescript 32 keyboard

[nourathar]

recently I got the keyboard assembly of a Dutch PTT Telescript 32 machine. I don't have a good picture of the whole unit to post here, and I could not find anything online about this particular machine, but from what I was able to find it looks like its internals are identical to a Siemens T1000S telex/teletype/fernschreiber. That model was introduced in 1985, which could be right for this one as well, it seems that really only the color scheme is different.

main.JPG (472.57 KiB) Viewed 3436 times

The keys come in three parts: the main keyboard and two groups of function keys that have a different type of switches, some of them latching. The switches on the main keyboard are surprisingly quiet and rather smooth, with a rather pronounced tactile bump and no real click. A bit like cherry browns or clears, but much more springy in sound and feeling and with keytravel that seems substantially more than 4 mm, more like 6 or 7. When in use, there was probably a lot of noise from the simultaneous printing of every letter, but on its own like this it is rather pleasant typing.

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fun1.JPG (302.14 KiB) Viewed 3436 times

fun1_latch.JPG (411.48 KiB) Viewed 3436 times

I really like the look of this block of keys, with weird telex-related legends in Dutch. Some of the keys have leds in them, and two wires that lead to the keycap.

main_fun.JPG (501.73 KiB) Viewed 3436 times

side.JPG (441.65 KiB) Viewed 3436 times

side_ledwire.JPG (490.01 KiB) Viewed 3436 times

I don't think I've ever encountered such a silent spacebar, perhaps because the stabilizers are partially covered in rubber.

spacebar_stabs.JPG (315.74 KiB) Viewed 3436 times

The keycaps are beautiful, spherical doubleshots, all the same profile. I do not know what the switch type is, but even though the stem is vaguely cruciform, the keycaps are not at all cherry-compatible.

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keycap_profile.JPG (377.75 KiB) Viewed 3436 times

keycap_doubleshot.JPG (352.24 KiB) Viewed 3436 times

There is no controller on this pcb. It does say '85', so that could be the year of fabrication.

pcb.JPG (560.98 KiB) Viewed 3436 times

pcb_detail.JPG (656.72 KiB) Viewed 3436 times

pcb_diodes.JPG (532.38 KiB) Viewed 3436 times

[nourathar]

And here some pictures of the switch internals, I am no expert, but I have no idea what type of switch this might be...

switch_open.JPG (378.93 KiB) Viewed 3435 times

The switches are very large, with long stems, and with no brand or other marks on them.

switch_internals.JPG (434.95 KiB) Viewed 3435 times

To me they look similar in principle to Cherry switches, but then much larger and much more sturdy.

switch_under.JPG (177.2 KiB) Viewed 3435 times

The little bump in the lid of the switch housing serves to dampen the return of the switches.

switch_lid.JPG (210.16 KiB) Viewed 3435 times

[HaaTa]

Oooooooooooooo.
This is new

The long circular stem probably is what makes it so smooth.

(If you ever want to part with it... )

[HaaTa]

Would you mind taking a pic of the underside of an LED keycap?

[Muirium]

The coveted HaaTa Doesn't Have It prize! You won!!

[Daniel Beardsmore]

Nice bit of overengineering there!

Interesting that it's gold crosspoint. I used to think that it was Cherry patented, but I've yet to find evidence of that. The earliest mention I have of gold crosspoint is from Cherry's 1973 Switches & Keyboards catalogue, where it's claimed to be another Cherry first. The RAFI Full-Travel Keyswitch series is gold crosspoint, but that appears to be 1975 onwards.

Still, it's not a common design. Alps opted for a soft metal foil membrane that's squeezed against the stationery terminal through a separator sheet, for example.

The gotcha with German products is that Google Patents doesn't have most of the illustrations, so you'd have to trawl through all the descriptions trying to guess whether you think it's the same patent. I wouldn't be surprised if this was Siemens's own switch, as it's distinctly different from other metal-contact switches. I doubt Cherry was making anything like this in the mid 80s, as the MX series was already out, and M11 and M9 have been found to have the same contact mechanism as M8.

The other thing you didn't mention is keycaps wired to switches! That looks like scope for a major blunder if you yank a keycap assuming that it's a bare metal contact or that the LED is inside the switch!

To be honest, that switch looks awfully large and outmoded for 1985, and it doesn't appear to offer anything that you couldn't get from a much smaller (and, for Siemens, suitably German!) Cherry M7 or (by that stage) M9, including the LEDs. There's a lot of complexity in the slider and movable contact assembly design though, and the patent would be an interesting read.

[nourathar]

wow, can't deny that I'm excited this is something even HaaTa doesn't have
but I'm sort of surprised this would be completely new.

It sure seems oldfashioned for 1985, but then I saw somewhere that the T1000S is a newer version of the T1000 telex machine, and that one came out in 1976. The main difference seems to concern other things than the mechanism (add screen and floppy drive), and it looks they did not change the keyboard at all. So the switch might date from 1976 ?

see some picts here:

http://teleprinter.net/english/inhalt/t1_e.shtml

and here a nighttime pict of the underside of a led-keycap, with two wires crossed..

led_keycap.JPG (168.85 KiB) Viewed 3406 times

[Icarium]

I just remembered why I spent so much money on keyboards when I spent more time on DT. X)
Nice find!

[sth]

with a regel vull, she cried more, more, more!

[OleVoip]

The gotcha with German products is that Google Patents doesn't have most of the illustrations, so you'd have to trawl through all the descriptions trying to guess whether you think it's the same patent. I wouldn't be surprised if this was Siemens's own switch, as it's distinctly different from other metal-contact switches. [...] There's a lot of complexity in the slider and movable contact assembly design though, and the patent would be an interesting read.

It might be a bit late, but I just stumbled over this thread, and there has a Siemens patent been published on this switch.