HP41cx problem


I have display problems as follows: when I turn it on, only the upper half of the screen shows and for me to get it to show properly I have to hold one corner of the calculator down, specifically the left bottom corner, or it has to be on a hard surface with all four feet firmly planted. It will not show unless I am sqeezing it or holding down a corner. I can wiggle the calculator and the display comes and goes. If I pick it up the display disappears completely or just the upper half. I can wave it around in my hand and the display will come and go. If I squeeze it slightly the display will stay, you get the idea. Is there something loose? I have played with the batteries, cleaned the contacts, etc, but have not taken it apart.

Any suggestions?


It sounds like you have a broken (or stripped out) bottom screw post. The fullnut HP41 machines have a CPU card that connects to the keyboard via a "zebra" type connector that uses the compression of the case to make contact. Typically the machine gets dropped and one or more of the screw posts breaks causing bad contacts. Another problem is the screw posts can split vertically.

You can try to glue the post back using a plastic welding solvent (typically dichloromethane) available in small bottles at most hobby shops. Despite what the bottle says let the joint dry for at least 24 hours.


another possibility is that one or more of the little tabs that connect the screen with the pcb have come un-soldered. they may not be making connection and still look tight so look real close. if this turns out to be the problem the good news is that it is an easy fix; they are relativly big and out in the open.

Possibly Related Threads...
Thread Author Replies Views Last Post
  HP41CX: Strange serial #... Stephan Matthys 1 276 09-13-2013, 01:38 PM
Last Post: Stephan Matthys
  Using PIL-BOX & ILPer to Transfer Programmes from PC to HP41CX? Michael Lopez 5 492 06-25-2012, 09:31 AM
Last Post: Michael Lopez
  Science Project with HP41CX and Arduino? Fouad M. Kaadou 9 668 01-04-2012, 04:04 AM
Last Post: yves
  Strange HP41CX Problem - HELP! Fouad M. Kaadou 2 306 11-20-2011, 05:12 AM
Last Post: Fouad M. Kaadou
  HP41CX - Strange turning-on behaviour Frido Bohn 8 624 05-04-2011, 06:05 PM
Last Post: geoff quickfall
  HP41CX power consumption Egan Ford 6 462 04-12-2011, 11:30 PM
Last Post: Garth Wilson
  Preprogrammed EPROMs for HHE PE unit for the HP41CX Prabhu Bhooplapur 3 320 01-28-2011, 02:08 AM
Last Post: Geir Isene
  Production Dates HP41CX Fullnut vs. Halfnut Frido Bohn 5 456 10-10-2010, 12:59 PM
Last Post: Jim L (OHIO)
  New HP41CX listed on Ebay Nigel Bamber 2 282 09-30-2010, 07:09 AM
Last Post: Jean-Michel
  Dropped HP41CX (carpeted floor), no longer working jim540 29 1,619 01-08-2010, 08:43 AM
Last Post: Mike Morrow

Forum Jump: