Anyone have a photo of a broken HP28S battery cover?



#10

I've been thinking of branching into the HP28S series, but would like to know a bit more about the battery cover problems (I've read about them from various sources). Does anyone have a photo of an example of a broken cover (or a photo of what typically goes wrong with these covers)? A precise description would help if no photo is available.

Thanks in advance!


#11

This is my 19BII which has the same case as the 28S

Both the battery door and the case are broken.

Marcus


#12

Thanks for the photo!


#13

I have been using a HP28S for 15 years.
This is my calculator of choice.

I can tell you that you have less than 10s to replace your batteries once the battery cover is removed otherwise you'll have your memory cleared.
The only method I have found is to shake strongly the calculator to eject the batteries with centrifugial force (without touching the "ON" key) and insert the new batteries immediately after.
Actually the memory is preserved as soon as you make contact with the battery cover, but if you don't know that, you may push the cover hastily and risk to break it at this very moment.


#14

If you get a "Memory Lost" message in ten seconds, then there's
something wrong with your 28S. The Owner Manual says that the time
limit is one minute, and I know that I've never managed to change
the batteries in ten seconds. The only accidental Memory Lost that
I've ever had was from replacing "low" batteries with "new" (but
extremely low) N cells.

Regards,
James


#15

Quote:
If you get a "Memory Lost" message in ten seconds, then there's
something wrong with your 28S. The Owner Manual says that the time
limit is one minute, and I know that I've never managed to change
the batteries in ten seconds. The only accidental Memory Lost that
I've ever had was from replacing "low" batteries with "new" (but
extremely low) N cells.

Regards,
James


Actually I have the kind of guy that keeps using his calc with "low bat" signal on for a very long time before getting new batteries.
The voltages may have dropped so low that the countdown becomes very short.

#16

A friend of mine has a 28S but doesn't know the battery size. Could you tell me?
Thank you.


#17

The HP-28S uses N cells (a.k.a. IEC LR1) -- the same size the HP-41 uses.


#18

And just in case anyone doesn't know, N cells (at least of the alkaline chemistry) are nominally 1.5 volt. Other chemistries will have somewhat different voltages, but may work with the 28 series. I'd guess a range of about 1.0 to 1.6 volt would probably work.

Some 12 volt nominal batteries have a similar size and shape, and look as if they might fit, but I expect that they'd fry the calculator.

Regards,
James

Edited: 19 May 2006, 3:48 p.m.


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