HP 48GX ON key

Hi, I have a HP 48GX that helped me throw collage so you must have an idea how please I’m with this calculator. For several reasons I had to put it away for a couple of years and now that I need it I found that my ON/CANCEL key isn’t working. I have already try the key test and failed. The only way I can make it work is If I apply a lot of pressure and in some times work and others doesn’t. I leave in Mexico and HP had told me that they do not have services for calculators. I believe that if I open it and clean the pad the problem is going to be solve, but… I don’t know how to open it or if it’s a good idea. Can some one help me. GRACIAS!


Good afternoon Marco. Have you tried to adjust contrast on calculator? Maybe it reset itself when sitting so long and need to adjust contrast. I believe I remember reading that if you turn on and then hold ON and + (plus key) it make contrast darker, and ON and - (minus key) it make it lighter.

Also, stupid question, but have you tried new battery? Does the ((*)) stay lit on the display?


Try gently pressing on the faceplate just above the "F" key, and then press "ON". If this makes it work, then do a search of the Archives here to learn more about it.




Hello Marco,
have a look at this thread too...




Its not the contrast, actually is in excellent setting (you are correct ON + plus key it make it darker and the other way around). The problem is that some times it works fine the button (ON/CACEL) and some time it doesn’t respond at all. I haven’t figured it out if a lot of pressure makes or not a difference. Batteries are new and the clac except this problem is working fine. Thanks for your reply.


Prego Massimo,

It was very helpful, know I have to find courage to open my HP. I will let you know how did it went.



It doesn’t make any differences. Thanks!


Ciao Marco,
actually you don't have to open it up: just check if the metal bezel around the ON key is loose or bent so that it stucks the key down.


Edited: 10 Aug 2007, 1:19 p.m.

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