Sony KDP-57XBR2 Training Manual page 68

DTV
SYNC
V5
DTV
INPUT
Y
TO IC515
FOR AUDIO
SWITCHING
Troubleshooting a "No Video" Condition
Using the block diagram in Figure 14-1 provides an excellent overall view of the stages of video processing to
utilize the various features of this chassis to assist in localizing failures. Since this chassis has four additional
boards attached to the A board, the steps to follow are needed just to find which board is causing the problem!
Verify the presence of high voltage and that no AKB error is occurring. If there is a high voltage problem, refer to
chapter 12 of the RA-4 chassis dealing with this circuit. If the unit is indicating an AKB error, refer to Chapter 27.
Once the presence of high voltage has been verified, and the AKB circuit is not displaying an error, press the
menu button on the remote to see if OSD will display. The ability to generate OSD helps to indicate the video
process IC511 is probably functioning properly.
The Picture & Picture feature provided by the BM board will assist in localizing the area in which the signal is
being lost. Since this circuit has the ability to display the main and sub video sources simultaneously, it is
valuable as a first step. The main path video should appear in the right box and the sub video in the left. Engage
P&P with the remote and determine where the fault lies based on the following results on the screen:
Video Appears In Both Boxes: The main and sub video process paths are working correctly. The MID is sending
the video directly into IC511. The problem is likely located on the BR board. This is the only time in which non-
HD sources bypass the DRC. The DRC circuit on this board is constantly running and not controlled by the I²C
bus. IC511 controls the selection of the video source. If video signals are present at pins 67, 69 and 69 of IC511,
replace IC511. No signals at these pins indicate the BR board is not sending up-converted video. Check to see
if video is entering the BR board and the 3.3V and 5V lines are OK. If they are present, replace the BR board. It
is not serviceable.
Video Appears In Left Box Only: The sub video path is OK. Once again, the DRC
small number of components to check. Begin working your way back from the YUV switch, IC1307. Scope the
video signal path back through the main decoder, and on to the BA board containing the 3D comb filter and A/D
converter. If the signal is present there, check A/V switch IC515.
IC511
VIDEO PROCESSOR
YUV
V4 IC1403
YUV MAIN YUV
INPUT SELECT
IVP
IC1008
MAIN CPU
FIGURE 14-2 - DTV VIDEO PROCESSING BLOCK
YUV IC1307
MAIN YUV
SW
ODTV
VIN
65
14. RA-4A Video Circuit Troubleshooting
Y
IC1303 Y
Y
SW
YUV
TM
is bypassed. This leaves a
H + V SYNC
TO DEFLECTION
CIRCUITS
TO TUBES
12 H SYNC
O720P
FROM
OSD CPU
IC1009/61
480I
TO
BR BOARD
14.2TVP14 6/17/02