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calculator key is stuck

topic posted Tue, December 20, 2005 - 4:07 PM by  Ovenette
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sharp EL-506G D.A.L. scientific calculator

the 7 key just stopped working. then the 4 also. this is my favorite calculator ever. and i don't ant to use something else. i love this calculator. I have reset it and the 4 started working again, but not the 7. and it just won't budge.
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  • Unsu...
     

    Re: calculator key is stuck

    Tue, December 20, 2005 - 8:12 PM
    last resort method:

    take the batteries out. fill a shallow, super clean container, big enough for your calculator to lay flat in, with isopropyl alcohol. bath your calculator in this, shake it around for a few minutes in the bath. shake the isopropyl alcohol out and hang dry. now put the batteries back in.

    if your calculator is solar powered, do all this in the dark.

    as you know isopropyl alcohol is used to clean electronics. it will not hurt them much if it has evaporated completly before turning on the electricity, batteries, etc..
    • Re: calculator key is stuck

      Wed, December 21, 2005 - 3:04 PM
      ach, do not submerge your calc in alcohol, simply take it apart, clean the back of the keys with iso and where they contact the circuit board then reassamble. simple as that
      • Unsu...
         

        Re: calculator key is stuck

        Wed, December 21, 2005 - 5:47 PM
        i agree, that would be best rick, but almost always they glue those things shut and you ususally ruin it taking it apart.
      • Re: calculator key is stuck

        Fri, December 23, 2005 - 12:40 PM
        I've removed the back. I discovered yet another panel that has about 8 screws. so now i need to remove those. but I'm just a bit nervouse that once I take those out, reassembly will be fiendishly difficult
        • Re: calculator key is stuck

          Fri, December 23, 2005 - 1:01 PM
          At this point there isn't much to lose.

          You *may* end up finding that the plastic key-caps of the calculator mechanically actuate the electromechnical part of the keypad. I've seen several design approaches used, so I can't be more specific.

          If surgery is unsuccessful, you can always glue the various "body parts" to a piece of clolored glass and make an art project out of it.
      • Re: calculator key is stuck

        Sun, December 25, 2005 - 12:30 PM
        I took the whole thing apart, rubbed it a bit with iso, then the 4 key started working...then the 7 key started working, but only lit up partially on the display, woth the top part chopped off, made it look like it could be either a 4 or a 7. then It was a miracle, and it started working again. so i put it back together. then later i turned it on, and nuttin'. no 4 or 7, again. even after a reset. any ideas?
        • Re: calculator key is stuck

          Sun, December 25, 2005 - 12:32 PM
          btw, whn the back is removed, I find a rubber pad that contacts the circuit board. I cleaned both. as i said it was working...but then after reassemble and an hour or so it stopped
          • Unsu...
             

            Re: calculator key is stuck

            Sun, December 25, 2005 - 12:47 PM
            My guess is one of the traces that leads to the key decoder matrix has a hairline fracture. This happens after years of pressing. If you can find which trace is bad you can solder a jumper across it. I hardly think its worth it for a old calculator though.
          • Re: calculator key is stuck

            Mon, December 26, 2005 - 9:50 AM
            It's toast! Give up!

            You can drop it off at Goodwill (they take old electronics for recycling). Last week, you could have bought the same calculator for $12 incl shipping on ebay.

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