posted 05-21-2015 10:04 PM ET (US)
Most modern marine electronic displays are liquid crystal displays (LCD). The brightness of the display is based on the light from the display backlight device. In older electronics, the display backlight was usually a cold florescent lamp (CFL). More modern displays have light emitting diode (LED) backlights.A common problem with older LCD displays is loss of light intensity from the CFL backlight.
Usually any sort of display has a control that adjusts the intensity of the backlight. Check the owner's manual of your particular brand, year, and model of marine electronic device for information on the location of any control that can adjust the intensity of the backlight for the LCD display.
It often happens that the backlight becomes very weak in its light output. This renders the display very hard to view in direct sunlight when the contrast ratio between the strong sunlight and the weak backlight is very bad.
The dark areas in an LCD display are created by the display blocking passage of light in those areas. There are two bounds on how great the blocking of light can be:
--a limitation inherent in the display, due to its design and construction, and
--an adjustment that controls the electrical signals sent to the display.
The first limit or bound cannot be changed; the display can only get to its least light passing condition, and that is the limit. The second adjustment is usually electrical and is provided on some devices as a user-adjustment. Consult the operating instructions for a particular device to see if the manufacturer has provided an adjustment.