HP-41CV

[burkhard]

The 41 calculators tried a couple of pretty clever ways to simplify manufacturing. These innovations generally worked as planned, but sometimes caused unintended reliability effects. I think what is going on with your calculator stems from the "lower posts" being cracked.

The two boards in the calculator are not electrically coupled with a ribbon cable but rather a squishy multi-wire electrical connector that is kept pressed between them. If the compression is lost, some connections can be as well. Constant pressure is supposed to be supplied by self-tapping screws on the bottom of the calculator going into plastic posts on the top. After 30+ years of aging, embrittlement, and being dropped/jostled a few times, those posts can crack and the screws lose their bite. No compression results and then the loss of continuity between the keyboard and the rest of the calculator.

There are LOTS of people who have fixed these and different methods. If you search the forum for "posts" and "41", I think you will find some ideas. I have repaired some minor cracking on mine when I had it apart to put a 41CL board in. In my case, it was pretty easy and free, but they weren't too far gone. For ones completely wasted, there are replacement parts available as well.

It is fixable and will be perfectly operating again afterward, but you'll need to take it apart to do this. Read up on it. Geoff Quickfall among others has written a bunch on this topic I think.

Good luck and keep us "posted." Heh heh