Changed the batteries in my 42S last week. I did so as quickly as possible, but the memory was still reset. Is there a way to change the batteries in a 42S without loosing the memory? Just would like to know for the next time.
Thanks!
Changing battery in 42S
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10-29-2011, 04:23 PM
Changed the batteries in my 42S last week. I did so as quickly as possible, but the memory was still reset. Is there a way to change the batteries in a 42S without loosing the memory? Just would like to know for the next time. Thanks!
10-29-2011, 06:47 PM
If the old batteries are not exhausted, internal capacitors / capacitance will keep some charge and thus the contents of the calculator will be preserved for about one minute, which should be enough. It is important not to short the terminals when inserting the batteries.
10-29-2011, 08:01 PM
Quote: Yes! Furthermore, this is likely to happen when one tries to replace them as quickly as possible. http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv016.cgi?read=102675
10-29-2011, 11:35 PM
Quote:Recently I needed three LR44/357 cells for a small UV light, and had none in the house. I had two Pioneers, a 17b and a 22s. Since I thought I could more afford to lose the Solver routines in the 22s than the 17b, the former became the donor. Much to my surprise, even after being out of the calculator several minutes, when put back in the 22s had retained all memory.
10-30-2011, 12:02 AM
The HP 42S has been my main work calculator for 14 years, and I've replaced the batteries at least three times. I've never has a "memory lost" condition during battery change occur on the 42S, or any other of my six Pioneers and four (old) Voyagers. I have the three new cells lined up, ready to go. Then I slap the 42S down in hand to make the old cells slip out, then I carefully insert the new ones, avoiding shorting of the battery clips.
10-30-2011, 01:25 AM
Quote:
I routinely use stacks of three cells bound with a single wrap
In any case the unified stack prevents inter-cell shorting and
[s/14s/42s] Edited: 4 Nov 2011, 5:28 p.m.
10-30-2011, 08:24 PM
Hi Keith,
The standby current of the HP 42S when power off is around 9uA by my measurement.
On the other hands, in the sleep mode, it'll goes down to less than 100nA at nominal temperature.
So it's recommended to put the 42S into the sleep mode by pressing
[EXIT], [+] and [XEQ]
simultaneously before battery replacement.
The other option is to connect an external power supply of +3.6~5V with series protection resistor of 1K Ohm before battery removal.
Good luck
10-31-2011, 06:01 AM
I did a light search and didn’t find a thread about, sorry if it has been discussed before.
10-31-2011, 06:33 AM
Hi Julian,
Please take a look at,
HP 27S : Irun ~= 6~11mA, Iidle ~= 340uA, Istandby ~= 8.2uA, Isleep ~= 170nA
Regards, Edit to use 'u' instead of using Greek mu character.
Edited: 5 Nov 2011, 3:43 a.m. after one or more responses were posted
11-04-2011, 03:36 PM
How can I enter sleep mode on my HP 32sII? /Sören
11-05-2011, 04:01 AM
Since the 32sII has no real time clock nor crystal oscillator, Lyuka
11-05-2011, 02:10 PM
Quote: How do you put a 27S into sleep mode?
11-05-2011, 07:39 PM
Just same as 42s. Lyuka
11-05-2011, 09:31 PM
Thanks! BTW you wrote:
Quote: for the 42s, it should be [ON] not [EXIT], correct?
11-05-2011, 10:16 PM
Where is this documented? I must not be looking in the right place.
11-05-2011, 10:31 PM
Hi Katie,
If you mean [ON] as the key that activate the calculator, either way will do.
Regards,
11-06-2011, 01:07 PM
Pressing that combination [ON/EXIT][+][1/x] or [ON/EXIT][+][XEQ] on my 42S does not do anything while it is in "ON" state, while it is in "OFF" state no visible change either it remains off. Edited: 6 Nov 2011, 5:40 p.m.
11-06-2011, 05:48 PM
Hi, Just try the key sequence below,
Press and hold [EXIT], press and hold [XEQ], press [+] and release, release [XEQ], release [EXIT].
Key sequence (timing chart) to put an HP 42S into sleep mode. [EXIT] ~~~~____________________~~~~
You'll see "Machine Reset" message at power on after sleep mode. Lyuka |
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