HP41CX weird behavior


I found a 41CX at a thrift store for the princely sum of $2. It seems to work for basic operations, however, it has weird problems with certain functions. For example, if I try “CAT 1” it doesn’t allow me to enter the number portion of the command. Trying “RCL 01”, it allows me to enter the “0”, but the “1” changes the command to a “ST+”. I took the batteries out for several months, and when I put them in again the screen displayed “EMORY LOST G”. In PRGM mode, there appears to be something still in the program memory, because when I try “GTO . .” it assumes it is program step 08. Hitting “BST” just locks the whole calculator up.

Any suggestions on how to fix this calculator?


Internal contacts probably need to be cleaned.


I would recommend first resetting the machine by holding down the gold shift key and the pressing and releasing the "ON" switch. You should see "MEMORY LOST".

If problems persist you will need to clean the internal contacts between the keyboard and the battery assembly and CPU cards.


Thanks to those who responded. I cleaned all the internal contacts with DeOxit and the calculator works much better.

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