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HP 41CX NULL MESSAGE - Printable Version

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HP 41CX NULL MESSAGE - Derek G. Graham - 01-01-2008

This is my first time on this message board so please take pity !

For the first time ever I have a "NULL" Message on my 41CX.

I cannot figure out how to get rid of it and get back to normal functions.

I have pushed all the buttons (and wiggled them too) but obviously not the correct one(s) or sequence(s).

I've tried to turn it off with the ON button but this does not work at all to shut it off.

Removing the battery clears the screen but on replacing the battery, the screen NULL message comes right back.

There is a program set by cards on the CX that can be re-loaded.

Any hints would be most greatfully received.

Thank you


Re: HP 41CX NULL MESSAGE - Karl Schneider - 01-01-2008

Derek --

"NULL" is the message displayed when a command is cancelled by holding its (last or only) key down for a few seconds. The message should disappear when the key is released.

Possibly, a persistent electrical contact is being made on one or more of the keys on your HP-41CX, due to mechanical failure or contamination.

One thing you could try is a master clear: Turn the calc on while holding down the backarrow (CLEAR) key.

If that doesn't help, I'd recommend inspection and repair by
www.fixthatcalc.com. The site owner has repaired several of my own fullnut (pre-1985) HP-41's.

-- KS

Edited: 1 Jan 2008, 4:36 p.m.