I've got an old Casio game calculator (MG-885 ... the 8-Attack game) that works fine, but the top of the display is very light with the two standard 1.5v batteries installed.

If I boost the voltage (with a benchtop PSU) to 3.6v the display is perfect, nice and dark. Unfortunately since you can't get 1.8v batteries I'm a bit stuck.

How (if its even possible) can I get 1.8v from each 1.5v battery to have the display look like this all the time?

I've checked the components (there aren't many - capacitor and a few resistors) and they are all within range of a known good working calculator so I think it's just that the conductive ink (this uses conductive ink on paper to go from the circuitboard to the LCD) has degraded over time — the calculator is nearly 40 years old — and just has too much resistance these days.

Here's a couple of pictures - one with 3v running through it, and one with 3.6v.

 

There might be a zebra strip in the calculator to connect display
to calculator chip. If you are careful you can clean it and board where
it makes contact to insure you are getting good contact between
display and calc chip.

Regards, Dana.