Strange HP41CX Problem - HELP!


Hello Hp museum,

I have recently opened up my Hp41cx to repair what I suspected was a broken screw posts problem but it was only broken posts on the back side of the calculator and by placing them correctly it is now firmly held together.

Now the real problem: After I reassembled the Hp41cx I was plugging in some modules and noticed that if I plugged any modules or card reader or printer or anything into the right ports (ports 2 and 4) the calculator will go crazy and not respond to anything unless I unplug the modules on the right side. The calculator works great if the right ports are empty. The left ports function properly.

Any Ideas? HELP!

Thanks in advance,



Disassemble and check for foreign matter under/on the i/o port block connector.


Thanks Randy. I found the problem, but I also have another problem:

I have a card reader that works on my other HP41C but when connected to the HP41CX the calculator would not even recognize that it is plugged in when I run CAT 2. although the port used by the card reader works properly with other modules.

Any thoughts?


Possibly Related Threads…
Thread Author Replies Views Last Post
  Strange HP 25 Problem (Repair) Onur Ilkorur 5 2,884 12-06-2013, 05:13 PM
Last Post: Onur Ilkorur
  Strange Battery Icon during updaate of Prime Firmware. Harold A Climer 7 3,515 12-05-2013, 04:40 PM
Last Post: Michael de Estrada
  HP PRIME : strange behavior when trying user key capability Damien 12 3,935 11-03-2013, 11:02 AM
Last Post: Joe Horn
  HP Prime function APP - Strange limitation ! :o( dg1969 2 1,584 10-04-2013, 12:10 PM
Last Post: dg1969
  HP41CX: Strange serial #... Stephan Matthys 1 1,163 09-13-2013, 01:38 PM
Last Post: Stephan Matthys
  [WP34s] strange behaviour at number entry Dieter 12 3,664 06-06-2013, 05:36 PM
Last Post: Harald
  Strange battery leak Cristian Arezzini 0 954 06-03-2013, 09:49 AM
Last Post: Cristian Arezzini
  Strange video Peter Niessen 9 2,832 04-07-2013, 08:33 AM
Last Post: Csaba Tizedes (Hungary)
  HP-41C Tall Keys Strange ON Behavior aj04062 3 1,706 12-02-2012, 06:49 AM
Last Post: aj04062
  HP15C strange complex number behavior Mike W 5 2,000 09-11-2012, 04:36 PM
Last Post: Mike W

Forum Jump: