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HP Forum Archive 14

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hp 41cx keyboard problem
Message #1 Posted by Nunez on 2 Feb 2004, 2:20 a.m.

Hello, i have an HP 41CX with a pb on keyboard : the / key doesn't make a "click" as the others keys (but it works). What can I do ? How can I open my 41cx without destroying it ? Where are the screws ? Thanks for your help.

      
Re: hp 41cx keyboard problem
Message #2 Posted by Victor Koechli on 2 Feb 2004, 4:43 a.m.,
in response to message #1 by Nunez

The screws are under the rubber feet. Access them by gently lifting the feet with a sharp device, such as an x-acto knife.

Repairing the keyboard is difficult because it's heat staked to the calculator front. You might be in luck, though, if your problem were that some heat stakes at the bottom have become loose. You could then try to re-attach the keyboard, and probably everything would be fine. However, I've never seen this kind of problem in a HP-41, but only in a Voyager (HP-15C).

If that is not your problem, I'd recommend to live with the / key as it is now. The key dome may be broken, which is not easy to repair. Chances are that any attempt to fix it will only make things worse, especialy as long as the key still works fine.

Just my 2 cents, Victor

            
Re: hp 41cx keyboard problem
Message #3 Posted by nunez on 2 Feb 2004, 5:21 a.m.,
in response to message #2 by Victor Koechli

thanks for your answer. I'm not sure I will open the calculator.

                  
Re: hp 41cx keyboard problem
Message #4 Posted by Victor Koechli on 2 Feb 2004, 5:29 a.m.,
in response to message #3 by nunez

Go ahead, open it and see what's going on. If it's not a simple problem to fix, you can just reassemble the calculator and continue using it as it is now. You can always try a more aggressive fixing strategy if the / key stops working one day.

Cheers, Victor

      
Re: hp 41cx keyboard problem
Message #5 Posted by Randy Sloyer on 2 Feb 2004, 7:47 a.m.,
in response to message #1 by Nunez

You have one of two problems:

  1. A cracked switch dome. Not an easy repair but it can be done. Requires removing the heat stakes to access the front of the pcb.
  2. Dirt inside the dome. This is easy by comparision.
For #2, here's something I have found to work in some cases.
  1. Identify the key from the back, each dome has an access hole in the pcb.
  2. Place two to three drops of UN-DU (heptane) adhesive remover in the hole. Wait 10 seconds.
  3. Using a canned air duster, hold the flex tube directly on the access hole and direct two short bursts of air into the key dome.
Hopefully the dirt will be carried out past the dome an imbed itself in the tape that holds the domes in place.

The whole calculator approach: If you have access to an ultrasonic cleaner, they work very well to remove dirt inside the keyboard as well.

            
Re: hp 41cx keyboard problem
Message #6 Posted by nunez on 4 Feb 2004, 3:51 a.m.,
in response to message #5 by Randy Sloyer

Thanks for your answer.

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