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28. Grand Wega Video Process
Video Problem Only with a single input or feature
Table 28-3 lists a feature and/or input that has a picture distortion and the corresponding board that is most likely
responsible for the problem. For example, if a video problem only appeared while watching a TV station but not
in a video input, the most likely cause is shown by the #1 under the A board column (A board defect). The # 2
under the U board column indicates a lesser possibility that the A/V selector IC is defective on the U board, a
second board choice. The remaining boards that process the other input signals are not suspect because the
problem does not appear with another input.
Table 28-3 - Board causing a Video Problem
Video Problem
appears only with
U board
BC board
BC4 board
BB board
Optical Unit
Assembly
A board
TV Tuner
2
1
Video input 1-4
1
3
2
S Video 1-3
1
2
Video 5, 6
(Component Video)
1
1
TV Out
1
Any input including
the OSD.
2
1
Mild Menu setting *
1
CCD
2
1
OSD
1
Twin Picture
1
1
* The “Mild” Menu video selection (Vivid/Standard/Movie/Mild) routes the signal around the Digital Reality
Creation Circuitry, feeding it directly into the MID IC. Noisy NTSC input signals can fool the DRC circuit
into introducing false picture improvements, adding to the noise, making the MILD mode useful with noisy
signals.
Using Twin View Mode to Locate the Video Problem
Twin View Signal Path Concept
This TV has the ability to display two pictures side by side on the same screen. In the “Twin View” picture mode
(Figure 28-3), both main and sub signal paths are used to produce the dual picture. The difference in the two
paths is that the main path contains the DRC picture enhancement circuit (left picture). Both main and sub
picture paths arrive at the MID circuit (BB board) to be assembled into a single picture. The rules for this Twin
View video processing are:
1. The DRC circuit can only be used for a 480i (NTSC) input signal.
2. The DRC picture will always be the larger picture.
3. When both NTSC pictures are the same size, the LEFT picture will be the DRC picture (using the main signal
path).
4. When there is a High Definition (HD) picture input (video 5 or 6), the RIGHT picture will be the DRC picture.
5. The RIGHT picture CANNOT select a HD (video 5 or 6) input.
Video switching in both the BC and BB boards will ensure these rules are followed. Figure 28-3 shows the
displayed signals with different inputs.
