HP 42S odd behavior and a temp fix.

[Diego Diaz]

Hi,

HP-42 keyboard is of the membrane type and the contacts with the CPU board are held in place by a pressure sponge (no hi-tech whatsoever). This pessure tends to get weaker as time goes by.

With this arrangement keyboard malfunction in the long term is a common failure for this series.

Regrettably, the only way to properly fix such problem requires to take the calculator apart to replace the sponge with a tighter one, which is not an easy task and often leave marks or dents in the case.

Sorry about the bad news.

Best regards from Caribbean.