Sony KDS-R60XBR1 - 60" Rear Projection TV, Руководство по обучению, Страница: 95 / 122

TVP-21 92
5. Video Processing System
The opposite of the previous conclusion is true if the video distortion
appears on the ATSC Tuner and Memory Stick inputs but not on the
Video 1, 2, 3. In this case, the defect would most likely exist in the Q-Box
module. The reason for this conclusion relies on the fact that Video 1, 2,
and 3 travels completely through the ASU/DSU Assembly and there is no
distortion. This provides a strong indication that the ASU/DSU Assembly
is functioning properly. The fact that the majority of the ASTC Tuner and
Memory Stick signal path is through the Q-Box module and the signal
is distorted provides strong evidence that the defect exists in the Q-Box
module.
The same deductive reasoning can be applied when troubleshooting video
defects using the other video inputs shown on the flowchart. This method
simple involves knowing the path the input signal must take through the
video processing system to reach the display. With this knowledge you
can effectively divide the video system into distinct areas, and therefore,
isolate the defect.
Optical Block
Optical Block
Troubleshooting
The primary objective of this troubleshooting flowchart is to determine if
the Optical Block, Video Circuits, or the Power Supply System is causing
the abnormal TV operation. The very first step is to eliminate or confirm
the Optical Block as the defect component. The quickest and surest way
to confirm proper Optical Block operation is to access and display the
ROOK test patterns.
Turn ON
PANEL SERVICE MODE
Internal Signal Generator
Because the ROOK IC7701 (located on the C-Board) generates the
test patterns, the patterns are applied directly to the LCD drive IC’s and
LCD panels bypassing all other video processing circuits. Therefore, the
Optical Block is isolated for troubleshooting purposes. If the patterns are
displayed then the Optical Block is OK and the video processing circuits
need to be examined.
Dark Raster
is Displayed
The next step is to check the raster intensity (or Overall LCD Panel
Lighting) when the ROOK test patterns are turned off and the TV is in
normal display mode. If the raster is dark, then this indicates no drive
to the LCD panels and you should go to the No Video Troubleshooting
Flowchart D to check the video processing circuits.
Bright Raster
is Displayed
On the other hand, if the test patterns do not display and the raster is
bright white, then the LCD panels are receiving drive signals from the
LCD drivers. However, no video is reaching the LCD panels. Therefore,
the next step is to check the power supply to the C-Board video circuits.
Check Voltage at
CN7954/pin 1
DSU--Board
The voltage at CN7954/pin 1 on the DSU-Board should be 16.5V. If
the voltage is missing then you need to troubleshoot the power supply
system, go to Power On Troubleshooting Flowchart B. The Main Power
Supply develops the 16.5V.
If the 16.5V is present then the defect exists on the C-Board. In this case,
replace the Optical Block because the C-Board comes as part of Optical
Block assembly.