Casio electronic calculator

[001]

Hi

My main gear is Casio FX-991ES ELECTRONIC calculator
Display contrast is adjustable by menu
But digits looks blue at any contrast value, not black

Can I replase polariser etc to get black digits?

[Kean]

How does this belong in Test Equipment category?

[001]

How does this belong in Test Equipment category?

Becouse  it is my test equipment 

[Gyro]

Almost certainly not, without destroying it.

[benj38]

I have successfully replaced LCD polarizing films in the past (though not on this specific calculator).

The good thing is that you can easily tell if it is indeed the polarizing film by simply placing a good polarizing film between your eyes and the LCD and observe if the contrast improves. Note that you should try this with the film rotated at different angles.

One can usually find replacement polarizing films for cellphones very cheaply on eBay. One such film would probably be several times bigger than the calculator LCD, thus allowing you to try again if you mess it up the first time.

The polarizing film has one side coated with glue, and if done carefully it can be applied by hand to a small display, such as one used in a DMM or calculator, without introducing any air-bubbles. Removing the old polarizer can be easily done with the help of a hot-air gun and a razor blade. Clean the leftover glue with isopropyl alcohol.

Note that the new polarizing film comes with an almost invisible protective film that should be removed when done (usually the protecting film can be identified by some printing on its edges: e.g., two thin lines) .

The usual disclaimer follows: try it at your own risk, You may do more harm than good if you are not careful, or if your particular LCD turns out to be the exception.