21
6. RA-3/3A Video Process Troubleshooting: T & S Models
IC1601
MAIN
VCHIP
PJED
IC002
SYSCON
IC1702
COMB
FILTER
CV
C
Y
IC1101
A/V
SWITCH
MONITOR OUT
CV
C
MC
RGB
RGB
RGB
IC1901
YUV
CONTROLLER
YUV
SW
IC1903
YUV
YUV
YUV
YUV
YUV
IC1902
SUB DECODER
IC206
YCJ
R
G
B
TO
C
BOARDS
PIP
OR
COMP.
SYNC TO
DEFLECTION
PIP
IC1905
MY
Y
IC301
Y SW
UV
COMPONENT
Y
SC
SY
OSD
C
M H SYNC
MY
Y
FIGURE 6-1 - S MODELS VIDEO BLOCK
INPUTS
SUB UV
MAIN UV
YUV SW
6.1TVP14
6/26/02
overall view of the video path. More detailed block diagrams will appear towards the end of this section. They
can also be found in the TVP-10 training manual. The goal at this point is to isolate the area in which the problem
exists and since there is a main and sub video path along with OSD, these features can be used to help locate
where it is occurring.
No Video: Many possibilities can cause this condition. The presence of audio is usually a good diagnostic tool,
but the set may be in one of the external input modes so it might not be there for you to hear. You should look for
the initial “must haves” and use the following steps to isolate the cause:
The first check is for the presence of high voltage. You should be able to hear it come on. If it does, the next
concern is if it is staying on. You could be dealing with a HV shutdown. Fortunately, this chassis will indicate the
shutdown by blinking the timer LED blinking in sets of six. Looking for lit filaments in the CRT guns is another
way to verify high voltage. If high voltage is not being generated, refer to the Chapter 5 dealing with deflection
troubleshooting in this manual to work on the high voltage circuits.
The next step is to wait at least 15 seconds and observe if the timer LED begins to blink in sequences of five. If
it does, you have an AKB error. Go to Chapter 27 in this manual that specifically deals with AKB and troubleshoot
accordingly.
NOTE: The RA-3 chassis does not blank out the video during an AKB problem, which is unique when compared
to all the others that utilize this feature. There still can be a “no video” condition with an AKB error such as loss
of G2 or total RGB output failure from the YC/Jungle.