HP 11C

[J Veteto]

I've lost my manual.I just changed bateries and all I get is 0.0000. None of the keys are working. What did I do wrong?

[David Smith]

Probably the processor is just locked up. According to Appendix D (pg 243?) of the manual you should LEAVE THE BATTERIES IN and then very briefly short the ends of the battery stack together with a piece of wire. They specifically state that you should NOT short the calculator battery contacts while the batteries are removed!

[db (martinez, ca.)]

two things;

i guess i got lucky. i was working on a made in usa 12c that i got at the flea for three dollars this weekend and i didn't know that i shouldn't short the contacts with the batteries removed. it unlocked with no problems but i won't do that again.

the pcb was labled 8122A. a lot of things hp made were 8XXX. is this the hp # for the whole calc or just the board? is the 22 in the number a nod to the old hp 22 that the 12 evertually replaced?