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Chapter 3 - Troubleshooting
CTV-68 12
TCON: Since the TCON allocates the RGB video information based on
specific timing information, the distortions tend to be fixed and usually
appear as symmetrical patterns that occupy most (or a significant portion)
of the display. Some examples of TCON errors:
• No video
• Thin vertical lines spanning most or all of the display
• More that one column of wide vertical columns which may appear
black or any color, or may contain distorted video.
• Multi-colored vertical line patterns with a repetitive pattern
Service Tip: Whenever vertical lines of distortion appear, select an
inactive input or disconnect the antenna in the tuner mode. The idea is
to not have a high-definition signal as the source. This allows the picture
zoom functions to operate.
Change the zoom mode from the remote commander. If the lines follow
the normal and zoom modes the problem resides on the BAL board. If
the lines remain fixed throughout the various zoom modes the TCON is
at fault.
LCD Panel: Distortions originating from the LCD panel tend to be
localized with the exception of horizontal line issues. A failure of a gate
driver can cause a horizontal distortion with all video content below that
point appearing distorted. Depending on which gate driver has failed the
distortion may only cover a small area of the bottom of the screen or a
large area of the screen if the driver failed near the top of the panel. With
the exception of visible physical damage, listed below are some examples
of LCD panel related distortions:
• Any single, thin vertical line (regardless of color)
• Any thin vertical lines isolated to a specific area of the screen
• A singe vertical column of lines of any color or containing distorted
video
• Any fixed horizontal lines
• Blotches of black or improperly colored areas
• Ghosting of images in which the entire image is repeated one or
more times
A thorough understanding of how the video is processed throughout the
chain of circuits all the way to the panel is important. A past article written
for the Sony Newsletter describes, in detail, how this process works.
A copy of the article is included in the appendix section of this training
manual.
The troubleshooting flowchart in Figure 3-3 will assist in isolating which
component is causing the distortion.