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new way to lock up a 41 - Printable Version

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new way to lock up a 41 - db (martinez, ca.) - 02-02-2002

my 41c shows "memory lost" no matter what, if the batteries are in. i have tried (or am in the process of trying) everything from the 4.1 section of Jedrzejowicz's book, even though that stuf is not exactly for this application. nothing has any effect. any ideas before i drain it and let it set for a year?

Re: new way to lock up a 41 - Ernie Malaga - 02-03-2002

I don't have the book you mention, so forgive me if this advice is a repeat: Have you tried unplugging all peripherals and modules? To unplug a peripheral or module, turn the calculator off, unplug it, then turn it back on.


Re: new way to lock up a 41 - db (martinez, ca.) - 02-03-2002

thank you, but that is the problem; i can't turn it off. i did however take out the batteries and remove the rom's. one is very suspect. can a rom go bad and can it lead a 41 down the highway to degradation with it?

Re: new way to lock up a 41 - Vieira, Luiz C. (Brazil) - 02-03-2002


I read your posts and I would like to know:

-did you open the calc?
- if so, is it a full- or half-nut?

In any case, there is a capacitor inside the calc (in paralel with the p.s. lines) that can maintain the calc`s circtuits charged for more that a couple of hours IF ON KEYS ARE PRESSED; try short-cirCuiting this capacitor's terminals (DISCONNECT ANY EXTERNAL DC SUPPLIES AND GET RID OF YOUR OWN ELECTROSTATIC CHARGES BEFORE DOING SO); I have solved many MEMORY LOST problems this way

My own HP41C was about 12 months-old (it was young enough I could count its lifetime in months) when the full-amnesia occurred. I inspected the calcualtor later (mine is a fullnut) and the first RAM IC was substituted for a new one. Yes, the first RAM is the one that holds system data, including the 169 all-is-well control flag. As this very RAM was the lost one, nothing could work.

I know this is only info, but may help.

My US$0,02.


Re: new way to lock up a 41 - db (martinez, ca.) - 02-03-2002

thanks marx. it is an old tall keyed fullnut, and since it has never been opened i'm trying to avoid popping the footpads off unless i have to.
i will be away from home till friday so i will leave it without rom's & batteries and with the battery terminals crossed with aluminum foil. i'll try it on friday night and if it's still a no go i'll try your method....carefully. i've had several open; just not this little jewell. if that doesn't work i'll just put it away without batteries for 6 months. that cured a cx that was very angry at me a few years ago.
thanks again and i'll check this site friday before i do anything drastic.

Re: new way to lock up a 41 - Joachim Kirsch - 02-14-2002

Hello !
I have the same problem like you whit my 41cv.All tries like
opening,cleaning,soldering severel contacts,shorting the contacts have been whitout succes.Did you had in the meantime a succesful solution?would be very glad to get an
answer.Thanks and greetings, Joe

Re: new way to lock up a 41 - db (martinez, ca.) - 02-14-2002

joe; i did just what i said i would do and got lucky. luiz explained the next step quite clearly, which was to short out the capacitor. this scares me a bit because i am just a staticly charged up kind of guy and that is why i did the lazy and slow way first. i also did the slow way because i had a week till i had enough time to take it apart. did you mean that yours displays "memory lost" all the time- no matter what - as long as there are batteries in the calculator? that is what mine was doing. i've had a couple of different lock ups since '83 and if you explain it maybe we can figure something out. if not we-as-in-me, then we as in everybody here. theres some real bright people that read the forum.