Top half of screen is darker than bottom half
The problem is most likley the TV backlight - it is very unlikley to be the graphics card or video input or any other circuitry within the TV.
Also, the problem can be manifested by flashing or flickering of one or both halves of the screen, and sometimes it is a left/right split rather than a top/bottom split, depending on where the lights are positioned. Before failure, you sometimes hear a very high frequency buzz for a few weeks before it fails - the frequency can't be heard by most adults as it ranges from 15kHz-25kHz, but children\animals can usually hear it.
Generally you will need to replace the backlight tube or the invertor that drives it. Generally you can identify the backlights as thin glass tubes buried deep within the panel itself usually with one wire going to each end of them - they are very fragile. The invertor is connected to the backlight tube and looks like a circuit board, often containing a high voltage warning. Usually there are two or four conductors connecting the invertor to the tubes, which can be identified as thicker individual wires as opposed to the flat ribbon wire used for data for the actual image displayed on the screen.
On some screens you may be able to unplug\swap one or both tubes to identify if it's the tube or inverter.
Oct 05, 2008 |
Flat Panel Televisions