Question about HP 12c Calculator

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Keyboard HP 12c

I can not work with "Zero" symbol and "+" symbol. Do you know how to fix it?

I have been running the normal test to find something wrong, but every thing seems to be fine.

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Under the rubber membrane ,touching the individual symbols (in this case zero & plus[+] there is a carbon coating (black stuff) that shorts out the two metal connectors on the board, when u press down on the keys
Open hp12c and lift up membrane away from body and see if the metal contacts[on the body] are warned, damaged or that the " black stuff " is on the membrane.
u can try a fix...........take a small piece of aluminum foil and glue it to the underside of rubber membrane where the "stuff" was.
Don't put a thick piece because the metal foil should bounce back with the membrane as u press down on the key.
Hope that helps.
I tried this once.........a small dab[ hey!!,, when I say a dab....i mean a dab....of glue. Sharpen a pencil & rub the tip across a EMERY board so that the carbon "black stuff" from the pencil falls on top of the glue. Let it set & try for 2 hrs or more.

Posted on May 14, 2008

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You can change the keyboard layout to match the one you have.

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Under the formats tab, change the format. try the ones with English (" ") and then click apply.
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The numers four and zero do not work om my computer

Most likely it's the keyboard itself and it needs to be replaced. You can try some of the following to see if it helps:

- Start Windows into Safe Mode. (See here for instructions)
- Open Notepad -- Click Start > All Programs > Accessories > Notepad.
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- Click the Start Button and select Run
- Type "devmgmt.msc"and click OK
- Click the + next to Keyboards
- Right-click on your keyboard and select Uninstall
- Click OK on the window that comes up.

3. Try booting to a linux live USB drive and test keyboard
- Create a Linux bootable USB drive (Click here for instructions using F8 method)
- Start computer from your newly created USB drive (Click here for instructions)
- Open Firefox or some other typing program and test keyboard.

If any of the above steps allow the 0 and 4 keys to work then the keyboard is fine and it's a software issue. Here are some further troubleshooting steps:

--Use MSConfig to disable all non-essential startups and start to normal.
--Enable startups one-at-a-time or in groups of 3 until the problem comes back. This tells you the problem is with one of the last items enabled.

-- You're done, Congrats!

-- Backup all your files and reinstall Windows.

If however, none of the steps fixed the issue your keyboard is bad and needs to be replaced

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Sticking/Under responsive zero key on an HP12c!! Is it trash?

It could be some dirt or grit in the keyboard, which a blast or two of compressed air might clear out. It could be a worn dome on the inside of the keyboard.
If you want to have it repaired, there's FixThatCalc, though they're currently not taking new orders. There also have been several threads on opening and cleaning Voyager series keyboards at the Museum of HP Calculators. Here's one article on opening a Voyager.

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My HP 15C calculator recently developed a problem with the number pad being unresponsive. Calculator appears to pass the self test, however, the key pad test does not work at all. Suggestions for repair?

If the keyboard test fails the calculator should be sent for repairs. One shop in Pennsylvania repairs most models, except the newer ones. The URL is Best of luck!

Dec 28, 2009 | HP 12c Calculator

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You hit a keystroke combination. You'll have to press the Fn key in the lower left side of your keyboard and one of the special function keys (in a HP, I think it's something like F11 or F12--look at the symbols on the keyboard. Anyway, that combo locks the special characters on. Just hit it again to get back to normal typing.

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I couldn't find any reference to a HP calculator model 12p.
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HP 12C

gtabblt.gif Description gtabblt.gif Resetting the calculator using the keyboard gtabblt.gif Resetting to drain the capacitor gtabblt.gif Other solutions gtabseps.gif Description Sometimes a calculator will lock up or will not respond correctly. The calculator may require a reset for a variety of reasons. These resets will erase the memory on the calculator and restore the calculator’s defaults. For this reason, it is important to back up any critical data. Resetting the calculator using the keyboard The easiest reset is done from the keyboard. To reset the calculator, follow the procedures below in the order presented.
  1. Press ON to turn off the calculator.
  2. Press and hold [ - ] .
  3. Press and release ON .
  4. Release [ - ] .
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  6. The calculator will reset to the default settings, and the memory will be erased.
If the above reset did not restore the calculator to normal, continue to the next section.

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