41 Auto shut-off


Hi 41-world out there !

I´m a HP (41)-collector for roundabout 1 year.
I got two CV´s (fullnut) and several peripherals for them.
All is in excellent optical and working condition.
The only problem is : auto shut-down occurs after a mere 30 seconds. For my older brain this is often too fast to finish thinking about the next keystroke. The Handbook tells that i have 10 minutes time until shut-off.
I guessed that there is a certain R/C-circuitry controlling this time and that a capacitor is just fatigue an should be changed. But looking at the schematics i could not identify the appropriate circuitry and the capacitor. Can anyone help me fixing that problem ?

Kind regards




Thanks Randy!

That was a great hint!

I tried it out immediately and for the first time i saw the inner life of that miracolous machine. First i thought "sh.." when i saw the fine-line contactors. But after thoroughly cleaning and drying i reassembled the 41.
After the first power-on the display shows crazy signs. "Gulp". So i did shortcut the power contacts and inserted the bateries again. WHHHEEEE !!!! It runs and even my programs are still there! Shut-down time is now 9:30 minutes and that´s O.K. for me.
By the way: can i use this time as an indicator for cleaning-service intervals?
i would never have found that thread without your assistance





I always disable the time-out. You can do that by executing ON or setting flag 44. Since I have my 41cx automatically do various things at turn off and turn on, I assigned the sumation key to my TOFF (turn-off) routine. One of the things TOFF does is set flag 11 so immediately upon turn-on, the program picks up execution again automatically. When it turns on, it sets the continuous-on flag (44), and checks to see if there's anything in my DAYTMR (daytimer) file that it's time to remind me of. If not, it goes on to see if there's an alarm pending, and if so, shows how much time is left before it comes due. Otherwise, it just puts the time and date in the display. Being on a 41, it's not instant, but the small delay is not a problem. I never use the ON key to turn the machine off, or let it time out. I suppose the time-out is good for forgetful people, but I find it quite annoying.


great idea Garth, iwill try this this afternoon,

thanks alot


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