HP11C permanently ON


Hi all,

yesterday, my HP11C (made in USA 1985) surprised me with a feature not seen so far: it didn't shut down! The day before it was working like always, but now it didn't accept any input from the keyboard anymore, displaying 1.7E-3 all the time. Removed and replaced batteries after some minutes: 1.7E-3 returned. Removed batteries again, shorted the terminals for some time, reinstalled batteries: all elements of the LCD show up, except the holy star! Stays this way for 12 hours now.

Any ideas??



I'd suggest briefly shorting the batteries' terminals with the batteries installed, as stated in all Voyagers manuals. The brief short circuit must be fast enough to ensure the voltage in their terminals briefly drops to zero AND THAT the batteries' energy is not drain too much. Of course, even the briefest short will be equivalent to some hours of calculator activity.

The reason to keep the batteries in place has already been discussed in this forum some time ago, and I still believe that the batteries make sure the voltage in their terminals never goes higher than 4.5Vcc, so there is no way to dammage the calculator with an ESD if they are in place. If you remove the bateries and short the calculator terminals without them, chances are that residiual static electricity is trasnfered to the calculator circuitry and it may hang. It may happen.

I prefer loosing a few hours of calculator activity...

My 2¢.

Luiz (Brazil)

Edited: 19 Jan 2007, 6:53 a.m.


Bom dia Luiz,

muito obrigado! It worked like a charm. Thanks for bringing my HP11C back to life!

Cumprimentos de Alemanha d:-)


O prazer foi meu. (My pleasure)

Hope it keeps working fine.

Luiz (Brasil)

Possibly Related Threads...
Thread Author Replies Views Last Post
  restoring an HP11C Alberto Fenini 12 2,633 03-14-2011, 09:24 PM
Last Post: Dallas Osborne
  HP11C Dominique Deprez 2 917 07-13-2010, 07:13 PM
Last Post: Vieira, Luiz C. (Brazil)
  removing alluminium bezel (was restoring an HP11C) Alberto Fenini 2 981 05-24-2010, 04:21 PM
Last Post: Alberto Fenini
  restoring an HP11C Alberto Fenini 0 630 05-20-2010, 06:20 AM
Last Post: Alberto Fenini
  HP11c - Swapping Internals Between Two DavidShenk 6 1,752 02-26-2010, 04:55 AM
Last Post: Frank Boehm (Germany)
  sticking key HP11C Pete Copeland 4 1,149 02-29-2008, 04:31 AM
Last Post: Walter B
  how to reset my hp11c Dirk (Japan) 1 749 02-05-2008, 06:56 AM
Last Post: George Bailey (Bedford Falls)
  HP11c showing all eights, won't shut off.... RP 3 1,029 11-01-2006, 08:31 PM
Last Post: Vieira, L. C. (Brazil)
  HP15C, or is it an HP11C? Gerald Waters 1 664 10-25-2006, 12:33 PM
Last Post: Charlie O.
  HP11c bad key? Marta 0 489 07-22-2006, 01:22 PM
Last Post: Marta

Forum Jump: