deskthority

https://imgur.com/a/cHojFYW

My apologies for some of the lack-luster pictures, but hopefully they at least give enough information to be useful. So I bought this on a whim from a seller on ebay, who claimed it came out of a Zenith board. (It was cheap, and the switches and caps appeared to be in good condition, so I said what the hell.) However, I cannot seem to find a Zenith board that even uses this layout, much less these switches, themselves I have not been able to identify. The layout appears to be sort of an AT equivalent of the layout on a Macintosh Plus extended keyboard, with the addition of the standard 12 function keys and an "EL" key. Note also the five LEDs, two of which are red. The closest thing I've found on deskthority to the switches are these white, alps mounted KPT clones: wiki/Alps.tw_Type_OB5 However, the switches on this board are marked with "AC" and then some number, and are linear. The ones described and pictured in the article are not marked, and are supposed to be clicky. From what I can tell the PCB is not marked or branded anywhere, whether it might be under the mounting plate I have no way of knowing. But as you can see it has what appears to be a TI microcontroller, googling the model number of which returns nothing. I've been able to find this information on Toshiba's website of the pictured CMOS Logic IC, but I'm not sure how much use that would even be. Also, I'm not really sure about what this 13-pin interface is. I've never seen another internal connector like it (granted I'm not at all any kind of expert.)

Any help at all in identifying what this is, what the switches are, or even what the interface is, would be greatly appreciated.

I bought one of these from eBay recently too. I was planning to get some pictures up today but I didn't have time.

As far as I know, the switches haven't been documented yet. What's odd is that they do seem to be KPT clones, but they're completely plate-incompatible with KPT switches. The KPT switches are too wide front-to-back to fit into the clones' plate, and the clones are too wide side-to-side to fit into KPT compatible plates.

Got some pictures but they're not great.


Contacts appear identical, though I did kind of mangle the AC3 contacts trying to get them out. Really didn't help that every single pin was flattened against the PCB.

KPT on the left. As you can see the AC3 is a fair bit wider.

Another side by side. The KPT is slightly taller.

Hey, the pictures at least certainly get across all the information. Thanks for taking the time to dissect them. Any idea who the manufacturer of the board might be? Could it be some zenith board itself not yet documented? Or at least, have you seen this internal connector before and what interface it would go to? That 13 pin connector is totally unfamiliar to me. I'd like to just see if I can plug this in without any kind of special conversion and see what happens.

I'm also curious to see what the actuation force on these are. They feel unusually stiff for linear switches. They to me at least feel as stiff if not stiffer than MX blacks when compared side by side.

Have you tried looking up the FCC id?

zrrion wrote: ↑Have you tried looking up the FCC id?

There's not one to be found, unfortunately.

I just saw this on eBay today and gave it some serious consideration until I noticed it wasn't ALPS. How do the keys feel? Are they delicious or bland?

They're pretty bad, in my opinion. Smoothness is very inconsistent but overall fairly rough. The worst part though is that you can actually hear the contacts on some of the switches. I might record a quick audio sample with my cheap desktop mic, just to give you an idea of what they sound like.

For me the smoothness seems decently consistent. Maybe our switches are not exactly in the same condition, maybe my taste in switches is not as refined. For me the main thing is the stiffness. They just feel weirdly stiff for linear switches. But yeah, you do hear the contacts to a degree, but that doesn't bother me particularly.