My HP-12c seems to be dead....

Good morning everybody,

This morning my belowed HP-12c (Singapore 3347S04420) is not responding to the ON button. I took out the 3 batteries and put them in again, but it is still not working. Yesterday it was OK and the batteries are almost new. I know that it hasn't a great value and that it is still sold, but I love THIS ONE !

I kindly ask you suggestions....

Thanking you in advance,

Best regards,



Take the batteries out and shunt the two connectors together with a paper clip. Then try reinstalling the batteries and hit the ON switch.



Thank you for the reply !

I tried, but it didn't work.

Other suggestions ?

BTW, I immediately ordered a new HP-12C, and while waiting I will use my dear old HP-41C writing some financial programs in order to transform it in a financial calculator. At least I will do some exercise !

Best regards,



HP manual suggests shorting battery terminals *while the batteries are in the calculator*.

Also, you may try exchanging batteries, even if the current ones are new. I would try that before buying a new 12c - China units are not as good as your Singapore unit.

There are some financial programs for 41 here:




Grazie mille, Massimo ! (Many thanks)

I have done what was written in the manual, now I will try new batteries as per your suggestion but anyway I want a spare unit (even a Chinese one).

I was in the middle of a financial meeting when the calculator died and I borroved a stupid algebric one from a collegue: now I know that I cannot work without RPN !

I am not an engineer but trust me that RPN works better also for marketing and financial people !

Thank you so much also for the link, it is very nice to see how kind and helpful is the people you find in this site !

Best regards,




I apologize....there are few with an Italian name and nevertheless I made a mistake...... I am suffering for my HP-12C.....



Besides, may I suggest you buy a used 12C instead of a new chinese unit. There are Singapore and Malaysia units around, and I bet they will last longer than most new chinese ones. You can even get lucky, and find a Brazilian or American one.

I´ve been in Italy in mid-90s, at Falconara Maritima, working on a telecom manufacturer. Nice country - Brazil has a large number of Italian origin people, and has inherited some features.




Obrigado muito muito !




Many thanks, Renato !

I did as you suggested, also with new batteries, and it didn't work, but after cleaning the contacts and doing it again few days later, it is working again now !!!

I agree with you about the China made units, I bought one as a back-up but the feeling is not the same as my old one !

Thank you again,




Ciao Luca !
I´m happy you got your 12c working again.
I was not surprised you succeded. There have been many horror stories - cars passing over, hypopotamus digestion, etc., and the 12c survived.

I also have seen some cases where a battery change turns up to a non-working calculator. I´ve seen this on 11c, 42S, 32SII and 41CV. Patience, some knowledge and persistance makes a necessary and effective solution.

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