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HP Forum Archive 19

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display compatibility
Message #1 Posted by alessio136 on 17 Aug 2010, 11:53 a.m.

some days ago a dark spot appeared on my hp15c display. i dont know how it could happen, maybe i just pressed it in the bag.

anyway, i'd like to fix it becouse i'm quite afficionated to that calculator.

i'm thinking to substituting the display with one from a hp12c. do you think it will work? since i dont own a 12c yet, i'm not sure aboute it...

for example, does the 12c have the exponent small digits?

thank you in advance :)

      
Re: display compatibility
Message #2 Posted by Eric Smith on 17 Aug 2010, 7:05 p.m.,
in response to message #1 by alessio136

for example, does the 12c have the exponent small digits?

No, but neither does the 15C!

The 15C display is the same as the display of a 12C from approximately the same timeframe, but not from one much earlier or later. You definitely can't use one from a 12C that uses one or two CR2032 coin cells; it has to be a 12C that uses three button cells. But even that isn't sufficient to guarantee that they are interchangeable. Early 12C and 15C calculators used a 2:1 multiplex display with about 52 electrical contacts, and later ones used a 4:1 multiplex display with about 29 electrical contacts.

            
Re: display compatibility
Message #3 Posted by Randy on 17 Aug 2010, 10:01 p.m.,
in response to message #2 by Eric Smith

Quote:
...You definitely can't use one from a 12C that uses one or two CR2032 coin cells; it has to be a 12C that uses three button cells...

Need to change "definitely can't" to "might be able to" as both the later three cell and the one cell 12C's all used the 4:1 arrangement as did the last version 15C with two IC's.

The only difference on the 15C was that for a while, they used a silver polarizer rather than the 12C's gold. They eventually used gold on the last 15C's. It is obvious if you're looking for it, otherwise you need to put an older 15C next to the later versions to see the difference.

The two cell supply 12C's have thermally bonded displays so they cannot be reused.


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