Re: foam pads. was: Successful keyboard jack repair

On Saturday, March 7, 2015 at 3:08:51 AM UTC-5, Simon Claessen wrote:
>
>
> I suspect that the thickness of the foam is not right and the foil is
> not touching the pcb. I've measured a still functional pad and it is
> 3.8mm heigh, 11mm wide. at the moment I am developing a production
> methode to fix our more that 10 keytronic keyboards (lisa, vt100, gigi,
> etc.) and yesterday I combined a Ikea mousepad, doublesided foam tape
> and the bag from potato-chips. I still have to check if the foil is
> right for the job, but the height is critical.
>

Here's some information on the subject I posted to cctalk a month back. The foam I describe comes closer to the original feel than anything else I've used. In all other respects, I followed Al Kossow's advice, using aluminized "Party Foil' from Michaels Crafts, commercial plastic sheeting and a cheap disc-cutter punch from eBay. Still a royal PITA, but great results.

I've fixed a couple of keyboards using hobby shop track bed foam, but have not been very happy with the "feel". That foam is considerably less resilient than the material Keytronics used. After trying a number of alternate materials, I have found something that is almost identical to the original. Take a look at eBay #171549720453 for an example.

It's 5mm thick with an adhesive backing, sold for shoe inserts. I stuck 0.075" plastic sheet to the backing, then turned it over and used spray adhesive for the aluminized mylar. Worked like a charm. Just finished resurrecting a N* Advantage and the typing feel is (in my opinion) far better than the last unit I did with track-bed foam (Corvus
Concept).

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