Seeking keyboard for Compaq Portable
christopher.parish at parishcomputers.com
Sat May 23 09:32:01 CDT 2015
I actually just finished re-padding mine last night. I struggled to find the right materials with the correct electrical properties, but I eventually came up with a process that works.
The mylar I had (conductive on one side and the plastic base on the other) wasn't working. The plastic side did nothing and the metal side shorted the pins. Out of frustration, I conformally coated the keyboard PCB with a thin layer of silicone (available at your favorite internet retailer), and now both aluminum HVAC tape and the mylar sheet (metal side down) work correctly. I stuck with mylar because the aluminum tape tends to develop sharp corners and can scratch through the conformal coating over time.
So here's the stackup:
Double sided tape (3M 9474LE 300LSE)
Coarse open cell foam cut to height
2mil thick mylar, metal side facing the keyboard
I used a 7/16" hole punch to shape each material. The resulting keys feel almost the same as the ones I didn't re-pad. Given the deterioration of the existing foam, I suspect that it's closer to the original feel anyway.
Hope that helps,
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