Component on case bottom of 48S

[TomC]

The keyboard to main board interface is certainly one of the weakest points of the HP48 hardware. Relying on simple mechanical pressure between the keyboard overlay and the plated 'fingers' of the main PCB is a design that is destined to fail over time - given temperature, humidity and hence oxidation at the interface point. (I also wonder about some liquid (?) that could be applied to this interface that would inhibit further oxidation and promote conduction over time. (?))

I've considered some type of more robust connection here, but robust connections to the keyboard overlay (which is a thin piece of plastic with carbon(?) deposited traces) is not possible. The beauty of a properly soldered connection is that it is much more robust - not subject to oxidation over time. Perhaps replacement (ultimately) with some type of thin PCB material (with appropriate resistance added) that has solder points is the ultimate solution.

The HP48 is such a great combination of utility (and (mostly) mechanical structure) that I hope it will see a long life (perhaps a 'rebirth' ala the HP42).

TomC