Advice for 15C for junk on display

[David Hayden]

A friend has a 15C with some funny stuff on the display. And advice what this is and how/whether it can be fixed? See the attached photo.

Thanks,
Dave

[burkhard]

(10-05-2018 07:36 PM)David Hayden Wrote:  A friend has a 15C with some funny stuff on the display. And advice what this is and how/whether it can be fixed? See the attached photo.

Thanks,
Dave

Wow, somebody uses "GRAD" mode!

Me thinks the display is (slowly) dying. I've never considered if the 15C shares an exact identical display with one of the cheaper Voyagers, but it might.

Running a self-test on a 1988 vintage 15C, a 16C (not cheap, I know), and a modern 12C (I don't have an old one handy), I see they all spit out the same digits, even annunciators like "GRAD" and "C" which I don't believe that the 12C makes use of. So, my guess is that he might be able to do a transplant from an old 12C which are pretty cheap, $20 or so. It would take a little online investigation to see how involved that is...

EDIT: Looking at the 12C guide, I guess they do use "C". No RAD or GRAD though, and there are still annunciators for those, which leads me to suspect the Voyagers (at least the vintage ones) might share a common display.

[Massimo Gnerucci]

(10-05-2018 09:09 PM)burkhard Wrote:  leads me to suspect the Voyagers (at least the vintage ones) might share a common display.

Yes, they do. Better choose a 12C from a similar time frame as the Voyager that needs a transplant.

[David Hayden]

Thanks for the advice. I'll let her know.

[everettr]

I have two HP 21S calculators that had large dark spots on their displays. In 2014, I kept one (Singapore 3010S04039) on my desk at work, where they never seem to turn off the bright fluorescent lights. Over the course of two months, the dark spot on the work calculator faded away, not yet to return.
For the at home calculator, I started storing it on a shelf under a skylight. Over the course of a year, the original spot slowly faded away. However, a smaller new squiggle began to appear.
Hypothesis: Bright light without IR fades spots, but bright light with IR component fades a spot while growing new ones.

[burkhard]

(10-08-2018 04:40 PM)everettr Wrote:  I have two HP 21S calculators that had large dark spots on their displays. In 2014, I kept one (Singapore 3010S04039) on my desk at work, where they never seem to turn off the bright fluorescent lights. Over the course of two months, the dark spot on the work calculator faded away, not yet to return.
For the at home calculator, I started storing it on a shelf under a skylight. Over the course of a year, the original spot slowly faded away. However, a smaller new squiggle began to appear.
Hypothesis: Bright light without IR fades spots, but bright light with IR component fades a spot while growing new ones.

That's an awesome empirical observation experiment waiting to be repeated!
You need to try setting up the home one under a fluorescent light.

[Csaba Tizedes]

(10-08-2018 09:07 PM)David Hayden Wrote:  I'm sure she'd be offended.

Maybe not. But some of the old fashioned members are yes.
So, I delete my post now, and you can share the link.
Or you can wrote her, her calculator is slowly dying and buy her a new one for Christmas.

Csaba