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Chapter 3 - Troubleshooting
CTV-68 11
FIGURE 3-2
NO VIDEO TROUBLESHOOTING FLOWCHART
No Video
Backlights
turned on?
Unplug LVDS
connector at
TCON while unit
is running. This
may need to be
done more than
once
Any flashes
seen on
screen?
Yes
No
TCON
(LCD Panel)
Any OSD
graphics
present
?
No
BAL Board
No
TCON
(LCD Panel)
Yes
Yes
BAL Board
Video Distortion
This is, perhaps, the more difficult failure to diagnose. It is difficult when
talking to the customer on the phone because an accurate description of
the problem must be obtained in order to determine which part (or parts)
to bring to the location. It may also be difficult for the technician when the
problem is witnessed.
If the problem is specific to one or more inputs it should be easy to
determine if the fault lies on the BAL board or a device that is plugged into
it. If the distortion occurs at all inputs it must be analyzed based on what
appears on the display and isolated to the BAL board, TCON, or LCD
panel. These components usually cause distortions that are unique to the
specific circuit. Below is an example of the typical distortions:
BAL Board: Since the video signal is processed on a frame-by-frame
basis it is very unlikely that a distortion that is occurring on a specific part
of the display panel is originating here. Distortion problems originating in
the video process circuits tend to affect the entire picture. Listed below are
some examples:
• Improper color reproduction or no color
• Improper luminance levels
• Lack of detail in the picture
• Distortions that change with movement in the video
• Diagonal lines
• No video