Reconditioning a 42S keyboard and bezel


The 42S I bought (S/N 32xx, ver C) had sticky keys. They did not stick down, but some keys resisted initial pressure then released with a click and pressed normally. It was usable but annoying. The metal front plate was also a bit loose on the right side, near the "RPN SCIENTIFIC" logo.

To fix the keyboard, I put enough 91% isopropyl alcohol on it to get some into the underside of the keyboard, then pressed the keys repeatedly. I wiped and shook out as much as possible. To dry the 42S I left it for several hours on a metal-cased fanless PC server, which gets quite warm but not too hot to touch. After two cleanings, the last one heated overnight, the stickiness is gone and all the keys work well. It remains to be seen if the repair lasts; has anyone done this?

The loose front plate is still a problem. I need to get some superglue under that bezel (1/2 mm crack or so) without getting any on the visible part of the calculator. Is there a known clever way to do that?



I need to get some superglue under that bezel (1/2 mm crack or so) without getting any on the visible part of the calculator. Is there a known clever way to do that?

Don't know it's clever or not, but I'd try with a needle.


If you go the needle route, a ready supply of syringes and needles is generally available at the local farm supply / feed store.


My very loose faceplate eventually came off entirely, so I didn't risk further damage by removing it--the worst was done.

Sticking this sucker down with CYA make me queasy. Rubber cement was a temporary solution but lacked hold. I eventually found fabric glue is a good compromise--the hold is a bit more avid but the excess pills away harmlessly like rubber cement.

I think you may get good results prying the offending corner up a tiny bit, tucking a bit of fabric glue in the corner, apply a little thumb pressure, and when the excess that exudes from the crack dries rub it away gently.

My rogue faceplate is curling up a little bit towards the bottom, but it has stayed tacked down nicely elsewhere. This fix is a few months old now. I also find the some of the apparent uneveness has improved, as though being held flat by the fabric glue has shaped the plate back partially toward a more desireable flat appearance. Not like new, but better.



I ended up lifting the edge a bit more with a jeweler's screwdriver, putting a drop of superglue on a piece of paper, and moving the piece of paper under the bezel to get glue on the underside of the bezel. This can be done without getting the glue on the edge. Then press it down and hold it for a while.


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