Older CRT Sony TV models may become dimmer as components such as the electron gun and the flyback transformer fail with age. These components must be replaced to restore screen brightness. Newer models have an automatic brightness feature that can be turned off or adjusted to remedy a dimness.
The official Sony troubleshooting entry for screen darkness recommends consulting the owner manual for model-specific help. General advice includes checking whether the TV is set to cinema mode or custom mode, both of which may have lower brightness settings. Restoring the TV to the factory defaults using a menu option may remedy the problem. Manually adjusting the screen brightness in the video submenu is another possible solution. Deactivating the Power Saving program on the TV may increase screen brightness at the cost of increasing power consumption.
Input devices, such as a DVD players or TV boxes, may also cause screen dimness. Connect the TV to a different source and check if the problem persists to determine if an input device is causing the problem. External devices may have brightness settings of their own that can be adjusted acceptable levels. Rear projection TV models, such as the Sony KDS series, can get dimmer as the lamp ages. Replacing the lamp restores brightness in such models.