Televideo Terminal Keyboard

[Tarzan]

This is mostly a thread to add some information to the GH collective, and as a build log for a hardwired version using a Teensy controller.  I don't expect a lot of people to rush out and source these obsolete keyboards, the linear switches they use are really stiff, more so than Cherry MX Greys.

I recently acquired three different Televideo keyboards; TS-800A, TS-802, and a TS-825 (800A and 802 shown below).  All of these have plate-mounted Futuba Complicated Linear switches, documented quite nicely on the DT Wiki: http://deskthority.net/wiki/Futaba_complicated_linear





Cases are varying degrees of yellowed, seller said these were stored on a shelf.  I've been Retr0briting them over the past couple of weekends, two have cleaned up quite nicely, but the third is still a shade of taupe along the lower leading edge.



The cases on these are burly; four screws hold the feet on, four more hold the case halves together, and four screws secure the plate to the lower case half.  Non-adjustable feet, the case is a massive wedge to hold the rear up at the right angle. 

Keycaps seem to be SS-profile.  Really thick, with Cherry-compatible stems, but each stem is set at an angle, so the keycaps are level only when the keyboard is raised in the rear. 

Switches can be removed once the PCB is desoldered (whole lotta pain doing that...), and come in different varieties.  There are plate-mounted stabilizers only for the space bar, and one lock switch for the caps lock (the black one in the pic). 



Plate is painted black on top, underneath it has some sort of metal finish, but age is taking a toll so there's some rust around switch openings.



I've painted the metal plate, using metal-etching primer and Navajo White paint (kind of a cross between eggshell and sand).  It's now a shade or two darker than the case, but most of the plate isn't visible once the keycaps are in place.



Switches are back in the plate now, I used a mix of the stock switches along with some NOS switches from Electronic Surplus - $3.00 for a bag of 20.  http://www.electronicsurplus.com/Item/150004/FUTABA%20-%20Switch_%20P_B_%20NO%20Keyboard_%20Package%20of%2020_%20-%20MD-4PCS/



As long as I had the keyboard apart, I've been lubing all the switches with Mkawa's GH lube.  Each switch is held together by the two pins, which are actually screws:

[SpAmRaY]

Interested to see what comes from this! Especially the wiring part.

[Tarzan]

Interested to see what comes from this! Especially the wiring part.

Thanks!  I've got a bag of diodes on my desk waiting to try the lowpoly solution, hoping I got the right ones...   

[SpAmRaY]

Interested to see what comes from this! Especially the wiring part.

Thanks!  I've got a bag of diodes on my desk waiting to try the lowpoly solution, hoping I got the right ones...   

I've got ~500 on the way from china

[rowdy]

From the DT page those little switches have 16 parts each!

No wonder they are called "complicated".

[metalliqaz]

Cool.  Looking good so far.

[Tarzan]

From the DT page those little switches have 16 parts each!

No wonder they are called "complicated".

Almost as if the engineer tasked with designing these was being paid by the part...   )

The only good thing is that they don't explode into 16 little bits when you open them; they can be opened, lubed, and closed again just by removing the two screw-in lugs.  Makes a big difference in the feel, the old stock switches feel kind of scratchy, but some grease really eases that.

[Daniel Beardsmore]

Hello there. Author of the DT pages on the Futaba linear switches here. One of my favourite switches!

Any chance of some internals pictures for the latching version? We don't know what's inside those yet.

Also, I notice that the enter key uses a pair of white base switches, while all the others have an orange base. Can you tell how those differ? Normally in that kind of arrangement you'd have one real switch and one dummy, but instead it's two switches of side by side, each with pins. Very odd! Any chance of some photos detailing this as well?

Cheers

Daniel.

[Tarzan]

Hello there. Author of the DT pages on the Futaba linear switches here. One of my favourite switches!

Any chance of some internals pictures for the latching version? We don't know what's inside those yet.

Also, I notice that the enter key uses a pair of white base switches, while all the others have an orange base. Can you tell how those differ? Normally in that kind of arrangement you'd have one real switch and one dummy, but instead it's two switches of side by side, each with pins. Very odd! Any chance of some photos detailing this as well?

Cheers

Daniel.

Howdy!  Thanks for your scholarship on these switches, your pictures are what motivated me to try making a hardwired version using these switches!

I'll certainly try and take some decent pictures of the latching switch, I have three in total so I can take one apart this weekend. 

The two white switches for the Enter key seem to use a lighter spring, and they also don't have locator pins - small plastic nubs on the square portion that fit into holes in the steel plate.  Not sure why they'd be free-floating when they are both soldered into the PCB, maybe it's to help in aligning them so they don't bind?  Speculation only.

I'll let you know what I find out!

[Daniel Beardsmore]

Thank you!

Feel free to upload some photos to the wiki too :)

[Tarzan]

Thank you!

Feel free to upload some photos to the wiki too

Will do!

[jalli]

I was lucky enough to buy a set of keycaps from one of these last week for 15€ with shipping, it was an 825 but the case was cracked and I didnt want to pay shipping for the whole thing half way around the world, still have not decided what to put the caps on but once I get them Ill post pics.

[Daniel Beardsmore]

Keycaps seem to be SS-profile.  Really thick, with Cherry-compatible stems, but each stem is set at an angle, so the keycaps are level only when the keyboard is raised in the rear.

Cherry M7 compatible? They're not Cherry MX compatible, but possibly M6/M7 — I forgot to add M6/M7 to Cross mount clearinghouse.

[Tarzan]

Keycaps seem to be SS-profile.  Really thick, with Cherry-compatible stems, but each stem is set at an angle, so the keycaps are level only when the keyboard is raised in the rear.

Cherry M7 compatible? They're not Cherry MX compatible, but possibly M6/M7 — I forgot to add M6/M7 to Cross mount clearinghouse.

You're right, the keycaps aren't actually Cherry MX compatible.  They fit on the switch stems just fine, but the outer diameter of the cap stem is too large to fit into the switch housing.  Probably would work on the flat Cherry switches.

Ironically, they do fit just fine on Cherry MY switches.  In this case, though, the slant of the cap stem means you'd have to have the back of the keyboard about 3-4 inches off the surface of the desk to get the right angle.

[Daniel Beardsmore]

For me, the simplified version and the MD-4PCS complicated (from Electronic Surplus) have sliders that are too large to fit inside a Cherry MX keycap (tried with Filco and BTC). A Futaba keycap won't stay on a Cherry MX switch. (All the Futaba linear series appear to take the same keycaps.)

A Cherry M6/M7 cruciform switch has a slider too large to fit into a Futaba keycap — they're even bigger still.

Not sure how you're getting them to fit!

[Tarzan]

Some pictures of the caps lock switch (left), and the switch used under the Enter key (right).



The all-white casing switch seems to be identical to the other complicated Futuba Linear switches


A few of the 16 different parts that go into each one of these.  That black square is a mini case, holding yet more micro parts...  (Please ignore the fact that I ripped several pads off of the PCB trying to desolder those pins!)


As long as I have it apart, a couple of dabs of Krytox would not be amiss.  There are four slider channels for the two-part(!) stem, I put a droplet in each one.


Buttoned up again

[Tarzan]

The Alpha Lock switch looks almost identical outside, but the sides of the stem/slider are different.  (Could have used a comparison pic here, eh?)


The casing and base for the lock switch are all black, other linear switches used in these keyboards are white/cream with orange or white bases.  [The black switches with orange bases are the new ones I purchased for this project.]


The stem on this switch is quite different, with a tiny lever-looking object pivoting on the side of the stem.


The free end of the tiny lever rides in a eccentric groove cut into a small white plastic plate - latching on one press, releasing on the next.


I lubricated the slider/stem, the dogleg lever/latch and the latch plate prior to reassembly.

[Tarzan]

Just as a data point, assuming the rectangular switch micro-case holds the same number of bits, this means that the latching Futuba switch has 17 different and discrete parts.  It still has a two-part slider (lever instead of plate), but the small white latch plate is additional. 

The more I find out about these switches, the more I like them!   

[Daniel Beardsmore]

Yeah I noticed that it only has a one-part slider. I love these switches, in part because they're so incomprehensibly strange. What does the two-part slider achieve? And the miniature rubber band around the little pivot point? The rubber disc inside the slider appears to increase the ping instead of dampen it (I reassembled a switch with the little damper missing and the switch was noticeably quieter).

It also answers my possibly only subconscious question about why there is that extra recessed slot on the opposite side of the slider — it's to hold the latch track part. It all makes sense now! OK, one little bit makes more sense …

[Daniel Beardsmore]

Wait a minute — no, the latching version must be 16 parts too, as the single-part slider won't have that little rubber band in the middle.

But, also, normally you have a little rubber disc inside the slider at the bottom of the spring recess — is that present? If not, it gets knocked down to 15 parts

[Daniel Beardsmore]

PS I presume all three have the same locking switch? (at least, outwardly identical)

Edit: I can't find any evidence that the TS-825 computer even exists ... I wonder what you've got there?

[Tarzan]

PS I presume all three have the same locking switch? (at least, outwardly identical)

All three keyboards are identical apart from the model tags.  Same mix of switches, at least.  One locking switch, two all-white ones on the enter key, the rest are white with orange bases. 

PCBs have the same mix of chips, the number on the large controller chip is only one digit different.

[Daniel Beardsmore]

Cheers, just wanted to get that clear so that I could use this topic as a reference without any guesswork. The TS series of computers look pretty nifty too:

http://bitsavers.informatik.uni-stuttgart.de/pdf/televideo/Televideo_TS8xx_Brochure.pdf

The 925 on the other hand is just a terminal.