What Does This Error Mean?

A faded Casio calculator screen is most often caused by a weak battery that can no longer drive the LCD at full contrast. Replace the battery with a fresh one and the display should return to full brightness. If a new battery does not help, the LCD polariser film may have degraded from heat exposure.

Affected Models

Casio fx-991EX
Casio fx-82ES
Casio fx-CG50
Casio fx-9750GIII
Casio ClassWiz series
All Casio scientific and graphing calculators

Common Causes

Weak or dying battery — LCD requires sufficient voltage for proper contrast
Calculator stored in heat or sunlight — LCD polariser film degrades
Contrast setting reduced (graphing models have adjustable contrast)
Cold temperature reducing battery output temporarily
LCD glass cracked internally — rare, usually from physical impact

How to Fix It

Replace the battery.

Most Casio scientific calculators (fx-82, fx-991 series) use one or two CR2032 button cells or AAA batteries. Check the battery compartment on the back. Install fresh batteries and test — a faded screen almost always recovers with a new battery.
Adjust the contrast (graphing calculators).

On the Casio fx-9750 or fx-CG50 series, the display contrast is adjustable. Press MENU then navigate to System Settings or use the key sequence SHIFT + 7 (on some models) to access contrast adjustment. Press the right cursor key to increase contrast and left to decrease.
Warm the calculator.

In cold environments (below 10°C), LCD display contrast degrades and screens appear faded. Bring the calculator to room temperature and test again. If the display recovers as the calculator warms, cold temperature is the cause — no repair needed.
Reset the calculator.

On Casio calculators, press SHIFT + 9 (RESET) and select All Reset to restore factory settings. A reset clears any software-based display setting that may have reduced contrast. Note: a full reset erases any stored programs or custom settings.
Check for heat or UV damage.

LCD polariser film degrades when exposed to direct sunlight or temperatures above 50°C (120°F) for extended periods — for example, left on a car dashboard. This causes a permanent yellowish or faded appearance that a battery change will not fix. Replacement polariser film is available for some popular Casio models as a DIY repair.

When to Call a Professional

If a fresh battery provides no improvement and the screen is faded uniformly across all segments, the LCD panel itself has degraded and the calculator needs professional repair or replacement.