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SteveH
February 18th, 2018, 05:53 AM
Oh boy, this is going to be fun, NOT.

I've acquired an LSI Octopus, Concurrent CP/M-80/86 based, computer and the keyboard (manufactured by Cherry) employs foam and foil capacitive keys. As is usually the case with these 30+ year old keyboards, the foam pads have deteriorated. However, unlike the typical Cherry or Key Tronic capacitive type keyboards, the foam pads are not disc shaped!

I think this is going to take time and experimentation to repair all 109 keys. :|

43821 43822

roberttx
February 18th, 2018, 06:24 AM
Do the foam pads absolutely have to be the exact same shape as the foil? I would first experiment on one or two keys, using smaller circular or rectangular foam pads. If you get lucky and find a shape that works, that would save a lot of time and effort.

SteveH
February 18th, 2018, 06:34 AM
I don't know as I've not got any suitable foam or mylar foil yet. I also thought of using rectangular pads, or maybe circular pads with two sides cut off.

snuci
February 18th, 2018, 08:39 AM
I don't know as I've not got any suitable foam or mylar foil yet. I also thought of using rectangular pads, or maybe circular pads with two sides cut off.

Regular mylar and foam pads cut to approximately fit will work. long rectangular should work. However, these are thinner than normal Keytronic foam and foil keyboards so you will have to make custom foam pads no mater how you look at it. I have two or three keyboards like this but I have not tried to reconstruct them.

JonB
February 25th, 2018, 02:55 AM
You do like a challenge, don't you Steve? Funny, I recall someone saying that to me!

I've done refoaming on my TRS80 Model II keyboard, but that uses circular pads. If you have no mylar foil, I believe silvered antistatic bag will work (the type of stuff components are delivered in). You could experiment with that and double sided foam strip. I expect the H shape is not too critical, but you can reuse the old film if you clean the glue off the back. I did this, by soaking each pad with meths and scraping (as shown in the video posted by TRS-Ian). Takes ages but with patience it can be done. Then you can reattach (making sure the film is the right way up) with square foam pads and leave the "ears" of the film floating.

Edit: https://www.youtube.com/watch?v=TvFcr03g-j0 <-- Ian's video has what you need, including cleaning the mylar foils.

Good luck!