85
20. RA-5A Video Path Troubleshooting
CB
BD.
7/17/02
20.1TVP14
ANALOG
TUNERS
IC002
SW.
Q9, Q11, Q13
MIXER
IC7806,
IC7807
DRC
PROCESS
IC8801
OSD
IC001
MAIN MICRO
IC7205, IC7603
DTV TUNER
AND PROCESS
IC205
MAIN SW.
IC8601
IC8703, IC8902
MID PROCESS
IC201,IC202,
IC204,IC207
ANALOG VIDEO
PROCESSING
IC401
A/V
SW.
IC200
COMPONENT
INTERFACE I/F
IC201 SUB SW.
NTSC
OR
HD
INPUT
CN4001/
CN003
NTSC
SUB
PATH
MAIN SIGNAL PATH
NTSC INPUT/ PIP
NTSC
MAIN
PATH
NTSC
OSD
OSD
MAIN
CN002/
CN3022
CN8601/
CN005
OSD
CN8801
CN001/
CN3020
VIDEO
5,6
VIDEO
1,3,4
CN008/
CN1200
HD
(33.75kHz)
VD (60Hz)
HB BD.
QM BD.
B BD.
U BD.
C BD.
A BD.
VIDEO
2
SUB
MAIN
A1-3
A5-7
C
11
13
C
15
17
HD
VIDEO
5,6
*
*
SERVICE MODE
ENABLED PATH
A3-5
A7-9
B
6
B
9
1, 3, 5
A9
MN-SB-
SW.
CG
BD.
CR
BD.
IC3006
VIDEO
PROCESS
AD
BD.
1,
2,
3
20
D
REG
YS
RGB
CN3012/
CN1601
CN3013/
CN1602
CN3011
CRT B
CRT G
CRT R
FIGURE 20-1 - VIDEO BLOCK - RA-5A CHASSIS
Troubleshooting a No Video Condition
Two possible causes of this symptom must be ruled out first. There must be high voltage present and the unit
has not encountered an AKB error. Listen for the sound of high voltage and verify it is remaining on by observing
that the CRT filaments are still glowing. This chassis does not indicate high voltage problems in the diagnostics
feature. If the high voltage is not present, refer to Chapter 19 for troubleshooting methods. AKB errors will be
displayed by the timer LED flashing in sequences of five. AKB troubleshooting will be covered in Chapter 27.
Once high voltage and AKB have been ruled out, try bringing up the customer menu. If it appears, there is a
good chance the video process IC3006 is working properly. If it does not appear, try entering the service mode.
The OSD for this mode comes from the main CPU IC001 on the B board. The appearance of the service data
also confirms the video process IC is likely OK and that there is a high probability the failure is on the Q board.
The purpose of trying to get OSD on the screen is to eliminate IC3006 as a source of the failure. It could still be
at fault since active video enters it via a different input.
Using the internal DTV tuner is valuable for isolating video problems. It has a direct path to the video processor
for HD signals and non-HD signals follow a direct path to the DRC
TM
. A lack of video from the HD tuner along with
no video from any of the external inputs or analog tuners points to a defective Q board. If DTV signals can be
received but not external sources, the next test can be performed.
The picture & picture feature will be used next. It is advisable to use the analog tuners when performing this test.
One item that is unique to this new feature design is that HDTV signals from the DTV tuner HD sources input to
video 5 and 6 sources can only be displayed in the left box. NTSC inputs and the two analog tuners will display
in either box. By using this feature, the main and sub-video paths are displayed together and a wealth of
information can be obtained to isolate the video failure.
