KPT (or possibly clone) comparison

User avatar
zrrion

03 Jun 2021, 06:11

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I have a few KPT boards at this point (a few more on the way, but I'll make another thread about those when they get here) and I think I can do a comparison to document switches I have seen pictured/mentioned but not really examined. I'll be upfront about these switches and the boards they come in though, they kinda suck. They're on paper built better than Cherry boards, but Cherry's execution is actually very well done for what they are giving you. If you want a clipped together board without mounting plates then Cherry gives you the best off the shelf version of that you can get, however if you want a screwed together keyboard with a plate there are likely few boards that do that worse than these boards. The plate is plastic, the case is thin and brittle, a lot of these boards only stabilize the spacebar, enter key, and right shift, and the later ones just resort to replacing most of the screws with brittle tabs. Cherry feels light whereas these feel cheap. I can't even recommend getting these for the caps either since you would still need a stabilizer for the rod stabs in the spaecbar and the BAE which this board integrates into the plastic plate instead of using discrete stabs. Taihao still sells BAEs that use this sort of rod stab but I can't find on their website where they well a stab for it so unless you somehow have stabs without the caps to go with them you can't even use these caps most of the time. Get them for as close to or under 20USD as you can. That said I think they have a certain charm in how badly they manage to do basically everything but as you might be able to tell from my calculator and typewriter posting I'm not really buying things that are good so take my like for these things with a grain of salt. The layout's basically perfect I guess ¯\_(ツ)_/¯

anyway, the switches are more interesting than the shitty boards they come in
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Left to right we have:
  • Yellow slider KPT "clones" from a Podworld 292 with a bigfoot style case, plastic back case, no function label strip, and detachable feet. This one actually stabilized all the keys.
  • Peach slider KPT "clones" from a Podworld 292 with a kinda focus knockoff look (this is the rightmost case in the lineup picture later on) this one uses clips to replace most of the case screws and doesn't have a locklight sticker
  • Blue KPT from a KPT102 with a kinda focus knockoff look (this is the middle board)
I'm not entirely sure if these are clones or if the KPT ones are merely KPT branded. There's not enough documentation to know for surte.

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same PCB footprint

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different plate-to-pcb distance, as well as plate cutout dimensions on all 3 of these switches. Blue KPT is alps mount. some later KPT boards use alps clones so this may have been future proofing, no idea why these changed plate cutout so much

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the contacts for these are all the same (and kind annoying to get out, so I only included one) but the click leaf is identical between all of them. The internals of these switches being so similar even though they don't have the same plate-to-PCB distance or plate cutout is really odd. I don't think they're clones, or the leaf would be different at least, but if they aren't made by different manufacturers then why would other dimensions be different? Maybe if the switches were made for a 3rd party it might make some sense that they would differ depending on 3rd party request, but PDC, JTC, and KPT branded boards have switches in this "family" all seem to just be rebrands of each other so afaik there isn't a 3rd party to sell these too. I don't recall these being compatible with another line of switches either so they aren't cloning something else. I still don't have any of the ones with ALPs style sliders or black slider yet, so it i possible that those ones actually are compatible with something like Omrons.

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the "ramp" on the blue slider is narrower than the other sliders. This would imply it was later in the timeline, and the chips on the blue board are dated `94 (and I have another blue board dated '92) while the peach one are dated `91.

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The peach ones are deeper, and I think the brown housing looks cooler.

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make sure you hold the outer contact such that it the inner contact doesn't get caught in it otherwise the slider cannot return as the contact traps it

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the contacts should look like this when reassembled, if not you will need to disassemble about halfway and try again.

Conclusions: these are definitely the same switch family, the internals are the same between switch. All the switches with KPT branding have KPT branding on the keyboard and the PDC (podworld) boards do not have this branding. I have yet to find any examples that break this rule, but I do not have any JTC boards, switches with alps style sliders, or black slider switches, so it is possibly there will be switches with non-KPT branding or branding on a switch that doesn't match the branding on the keyboard. (the KPT PCB says KPT and so does the controller, but on a podworld the PCB has PDC, but the controller just says KB, so possibly KPT wanted their name in more places?)
Blues are a lot louder for reasons I cannot fathom
Peaches are quieter
None of them look like they were ever lubed, maybe they get better with lube but I don't know how much better that would get you really.
apart from weight and sound they feel the same, which is to say they feel like worn white alps. The examples I have are bindy too, but you can kinda see the sliders aren't particularly clean so I can't hold that against them.

User avatar
Polecat

03 Jun 2021, 06:38

Thanks, interesting and very informative. I have a later KPT-84 with Tai Hao Alps clones, and I'm glad I got it instead of the earlier version with KPT switches. I can at least swap in genuine Alps when the clones go belly-up. It gets limited, but frequent use on a P1 that runs my ancient SCSI page scanner.

User avatar
zrrion

03 Jun 2021, 06:49

Yeah, the switches are good enough if you've never tried good switches lol. The later ones where they gave up and just used ALPs compatible clones are probably the best to seek out since you can swap the switches. I'd love to know more about the history of KPT or whoever OEMed these, it seems like a lot of trouble to go through to make your own switch/keyboard line to just kinda leave no documentation behind of any sort.
I have a NOS black one with ALPs clones on its way to me at some point. I also have a different 84 on the way as well with black slider KPT. Excited for both honestly. Now if I could find some of the white slider ones I'll have all the flavors I've seen thus far.

User avatar
Polecat

03 Jun 2021, 07:05

My Alps clone KPT84 is the same layout, but with black and gray caps. Really not bad, I said Tai Hao clones but I meant Hua Jie, and those usually don't hold up well over time. But I got it NIB and it's been good so far. The "different 84" looks very much like a Focus FK-727/747 clone! I almost bought a Datacomp DFK-171 with what looked like black KPT switches a while back, but someone beat me to it. Like you I was curious about the switches. I had a keyboard with what were probably blue KPTs about 30 years ago, and "cheap" was my impression at the time.

User avatar
zrrion

22 Nov 2021, 04:11

I have since acquired white slider slider black housing and black slider black housing versions of these switches, no major differences to report. click leaves are the same between all examples I have at this point. I've seen a pink slider brown housing version and yellow slider brown housing as well (and a green slider brown housing, but that's a spacebar switch) that I haven't been able to get ahold of yet either. I don't expect to see any significant differences but it'll be nice to get most of the variations finally. I still haven't ever seen the alps style sliders anywhere other than listings for NOS parts. haven't bought any yet, maybe they're different in some way.

EDIT: almost as soon as I posted about not finding alps style slider KPT in anything I found a highly fucky board with yellow alps style slider as well as a single white alps style slider which I was previously unaware of. It's cheap as well so hopefully I will put some funds together for a reasonable haul of KPT stuff shortly.

Jan Pospisil

23 Nov 2021, 19:25

Speaking of KPTs, I just saw this Costar board with blackNblack ones. (? I think)
https://www.ebay.com/itm/125012320015?

Previously I think these boards were known to have Alps. (?again - I think?)

User avatar
Palatino

23 Nov 2021, 19:38

Jan Pospisil wrote:
23 Nov 2021, 19:25
Speaking of KPTs, I just saw this Costar board with blackNblack ones. (? I think)
https://www.ebay.com/itm/125012320015?

Previously I think these boards were known to have Alps. (?again - I think?)
I’ve been watching this one since it was listed: a dangerously good-looking keyboard. It’s going to put my one out, one in policy to the test.

User avatar
zrrion

23 Nov 2021, 20:21

That does look like black-black KPT, if I didn't already have a boxed podworld board with those it would be mighty tempting.

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