I have an old HP-12c I used when I was in Real Estate. It's been sitting in a drawer for the last 10 years. Recently a friend of mine needed a calculator to use in his Real Estate business so I dug out the old 12-c and bought a new set of batteries for it expecting it to be "good as new"

When the batteries are in, the display remains at 0.00 no matter how many times I try hitting the ON button.

I hate the idea of just junking it, as I have the manuals and a complete set of tapes on how to make the best use of it plus I love the old clunker and I'd like to past it on.


(1) Is there something I'm doing wrong?

(2) The batteries are Energizer 357's are they possibly the wrong type? Frankly when I replaced them I just assumed the guy at Radio Shack was selling me the right ones.

(2) If it's just broken is it worth repairing and if so where?

Thanks for any help or suggestions in advance.



You got the right batteries,I think the keyboard is causing the problem,one or several keys are stuck.Try blowing on the keyboard or hit the calculator just hard enough to release the key or keys that are stuck.Good luck.



what recently helped me, was to shorten the battery contacts with a short cable (wihout the batteries in the calculator) to unload the build-in capacitor.



Andreas is right but the proceedure in the manual specifically mentions shorting the battery contacts briefly with a paper clip *with the cells in place* (Briefly is <1/2 a second) Though I doubt it makes much difference it is a little less violent to the circuitary. What happens is a static charge builds up in the machine, shorting the contacts dissapates this.

Possibly Related Threads…
Thread Author Replies Views Last Post
  HP 12C, 12C Platinum & 15C iOS App Walter Lam 2 1,424 06-02-2011, 01:25 PM
Last Post: Andrés C. Rodríguez (Argentina)
  12C vs 12C Platinum Cash Flows Katie Wasserman 10 2,890 12-28-2005, 10:12 PM
Last Post: tony(nz)
  12c/12c Platinum programming differences Don Shepherd 6 2,046 08-11-2003, 10:11 AM
Last Post: Gene
  12C or 12C Platinum...that is the question Joe 3 1,364 06-21-2003, 11:39 PM
Last Post: Don Nguyen
  What's CPU of HP 12C and HP 12C Platinum Luc Chanh Truong 3 1,455 06-11-2003, 01:49 AM
Last Post: Vieira, Luiz C. (Brazil)
  Hi !! Gene, HP 12C vs 12C Platinum Luc Chanh Truong 0 810 06-09-2003, 10:28 PM
Last Post: Luc Chanh Truong
  Re: Inconsistent results #1: 12c vs. 12c Platinum hugh 1 955 05-14-2003, 03:22 PM
Last Post: Gene
  Inconsistent Results #2 and #3: 12c vs. 12c Platinum Gene 3 1,301 05-13-2003, 06:58 PM
Last Post: Patrick
  Inconsistent results #1: 12c vs. 12c Platinum Gene 3 1,249 05-13-2003, 11:58 AM
Last Post: Vieira, Luiz C. (Brazil)

Forum Jump: