Old keyboard replacement rubber domes

cr0ft

08 Oct 2019, 17:17

I realize that starting my first ever post here with a dome keyboard may forever cause me shame and suffering, but the problem is I have a pair of keyboards I've been using so long they feel more like extensions of me than keyboards. This means I'm willing to go to some lengths to keep them going. I'm using one at home and another at work, and have been for years. So I'm hoping I can get some help finding the parts. These things saved my hands, I was experiencing RSI already, with these that went away. So I'm real sentimental about these.

They're a pair of very old Keytronic rubber dome based boards by "ergoLogic"; essentially a tenting keyboard made by Keytronic for/with ergoLogic (yes that's how they capitalized it). Keytronic made their own variant too, I forget the name. Neither type was available for very long but I believe they use standard Keytronic domes from that period.

Anyway, they're wearing out. So I'm trying to find new rubber domes and such to refresh these to as new state, or as close as I can get. Anyone have suggestions for where I can find a pack/kit? Ideally low 1 ounce force, but I'm not proud at this point, I'd take the standard 2 or 2.5 ounce, not sure which they shipped with off hand. I'm not sure what the switches look like deeper down, but perhaps there is stuff there too that needs replacing, anyone know? I'm new to the whole idea of actually digging deeper into keyboard guts.

The keyboard has actually been mentioned here before; this is what the switches look like https://webwit.nl/input/ergonomic/ergologic/37.jpg - not my picture, found a bunch of images https://webwit.nl/input/ergonomic/ergologic/ here.

In my dream world it would be possible to convert these to mechanical but I suspect that would be a bigger job than it's worth? New custom PCB's, all new keycaps, something with the electronics... probably just a pipe dream; it's not like I can't live with the action, having done so for over a decade now.

User avatar
abrahamstechnology

08 Oct 2019, 17:41

We ought to convert this to use BKE domes and a really thin capacitive PCB to replace the membrane. I don't know anything about capacitive PCBs though.

cr0ft

08 Oct 2019, 17:48

Yeah, I'm really new to all of this, I mean I have a passing familiarity of mechanical keyboard switches and the like but I'm a total novice when it comes to actually opening a keyboard up.

I've been going through the wiki and googling my heinie off and I'm beginning to suspect that these keyboards are “Foam and Foil” capacitive, so what I really need are the foam and foil pads, and possibly new rubber domes? Does that sound reasonable to umm anyone?

Though the real issue is probably the foam and foil wearing out on me. I mean, just to get these back up to speed as rubber dome keyboards that actually works.

Going mechanical is more of a dream, not a necessity. :D

User avatar
abrahamstechnology

08 Oct 2019, 17:53

I was thinking more along the lines of Topre-style capacitive domes but I am not really sure how to accomplish it.

Perhaps BKE Light domes can be used and a 3D printed part could be made to push down on the existing membranes.

Findecanor

08 Oct 2019, 18:01

Converting to use BKE domes would be easier said than done, because those are full domes to fit within a very specific switch, not rubber sleeves.

Yes, the switches in Webwit's images are Key Tronic Foam and Foil. The rubber sleeve that goes around the slider is what provides the resistance and tactile feedback.
Each slider has a disc of foam on it, with a metal foil disc glued to it. The foil gets close to the circuit board at the bottom to actuate. The foil is actually not conductive, but affects the capacitance between large pads on the circuit board.

It is often not the rubber sleeve that wear out but the foam pads inside the keyboard that deteriorate with age.
I do have a bag of rubber sleeves that I have scavenged from another old Key Tronic keyboard, but the foam pads are long gone.
If the foam is what's broken, then the keyboard should feel the same but the switch should just not work.

Edit:
Here's a source that sells the pads: https://texelec.com/product/foam-capaci ... keytronic/

I found another maker/seller on eBay but those pads don't include the mylar sheet, so you'd need to replace each one from the old pads. (fiddly work...)

User avatar
abrahamstechnology

08 Oct 2019, 19:18

Oh I was under the impression that this was a regular Keytronic rubber dome.
Actually right now I'm converting a Keytronic Foam&Foil (regular fullsize ANSI) to use MX switches. Since the plate cutouts are slightly too large to clip the switches in I'm going to have to suspend the PCB off the plate with standoffs (designing a new PCB from scratch for this) Perhaps something similar could be done with your board?

Do the switches on your board look anything like this?
Image

cr0ft

08 Oct 2019, 19:56

Findecanor wrote:
08 Oct 2019, 18:01

It is often not the rubber sleeve that wear out but the foam pads inside the keyboard that deteriorate with age.
I do have a bag of rubber sleeves that I have scavenged from another old Key Tronic keyboard, but the foam pads are long gone.
If the foam is what's broken, then the keyboard should feel the same but the switch should just not work.

Edit:
Here's a source that sells the pads: https://texelec.com/product/foam-capaci ... keytronic/
Yeah, I was cleaning these today and gave it a little blast of compressed air; I suspect that did something I didn't want because the A key and the enter key both went dead on me. Some frenzied pecking later they started working again, I probably displaced whatever I managed to blow into the switches... but that was a wakeup call.

I think I'll follow that link to the seller and hope they do have those capacitive pads on hand, and then replace those and clean these from top to bottom, inside and out. The rubber domes are probably still in decent shape, at least I still get a tactile activation so it doesn't seem like they're entirely dead yet. If and when that happens I suppose it's time to consider drastic action to try to convert to mechanical.

I wonder if you can even get these rubbers, I'm a bit surprised there's a source for the pads, but I'll take it! :)

At least these keys aren't linear or quite as bad as the real cheapo domes. Could be worse. Thanks for the input guys.

cr0ft

10 Oct 2019, 14:48

Got a bunch of pads coming so the rescue mission continues. A pity I can't seem to find the buckling rubber domes anywhere though. Swapping those out for new would be nice if I'm tearing these down anyway, but oh well, probably not absolutely necessary.

User avatar
ZedTheMan

10 Oct 2019, 16:37

I actually once had one of this board, under the Keytronic Flexpro name. I sold it to another user and included some springs to linearize it.
One thing to look for is other Keytronic Foam and Foil keyboards secondhand, they tend to be a bit cheaper as for most people they aren't highly desired. This could get you more of those buckling rubber sleeves, or perhaps some springs so you can try them linearized. (I think foam and foil feels much better as a linear switch than with the tactile domes but it's possible you like the feel of the dome so that is okay too)

Post Reply

Return to “Keyboards”