46
11. Video Process - HA-3 and RA-5A Chassis
Flow Charts for locating a defective board
In the Twin Picture Mode the main picture video signal path is always used to display the largest picture. To do
this the MID circuit in the Q box and switching ICs on the B board may interchange paths depending upon which
picture is the largest. Use the flow charts to change the size of the pictures in Twin Mode and isolate the problem
to a board.
Figure 11-2 - Twin Picture Mode, Analog Inputs
Main
pix
IC205
Sub
pix
IC200
Main pix
from IC205
S
Main pix
from IC205
S
a
b
c
WHICH PIX?
QM BD.
PROBLEM
WHICH PIX?
RETURN TO 1 PIX.
TURN ON THE INTERNAL
VIDEO GEN. (SERVICE
MODE)
*
DEFECT IN THE
GENERATOR
PATTERN?
IS THE DEFECT IN
ALL MODES?
VIDEO, TV?
NTSC/480i
SINGLE PIX
HAS A DEFECT?
PROBLEM EXTERNAL,
OR ON B OR U INPUT BDs
ANALOG PROBLEM
IN A, B, OR C BD.
QM BD.
DEFECT
(MID IC8703)
MAIN AREA
B BD. IC207,
IC205, QM BD.
IC7807
LEFT
RIGHT
SUB AREA
B BD. IC200/
IC202
CHANGED
PIX
PROBLEM IS IN
A/D IC8601
MID IC8703
LARGER
SAME
PIX
SMALLER
NO
YES
YES
YES
NO
PROBLEM
IN A/D IC7806
DRC IC7804
NO
FIGURE 11-8 - FLOW CHART 2 - VIDEO TROUBLESHOOTING - NTSC PIX DEFECT
39TVP12 1355
8/30/01
PRESS "TWIN MODE".
MAKE LEFT PIX
LARGER. DO BOTH
PIX HAVE THE
PROBLEM?
*
SEE "ADJ. OVERVIEW" SECTION
MAKE THE RIGHT
PIX LARGER.
WHERE IS THE
DEFECT?
Signal Tracing to prove the problem is on the board
Refer to the following to support the traditional video signal tracing in the HA-3 and RA-5A TV chassis:
•
Figure 11-1 for the signal flow
•
Figure 11-10 for the location of HA-3 chassis connectors.
•
Chart 11-4 shows the Video Signal Levels along the way
•
Waveforms 11-1 – 11-3 that show the signal shapes with an NTSC color bar input to the TV.
Conditions of measurement - Color bars are input to the main (VHF/UHF) and sub (Cable) tuners from two
separate NTSC generators for ease of signal tracing. The color bar signal is followed as it enters and leaves a
board. The Sub signal is always present at the connector even though it is not being used. The TV is tuned to
Channel 3 and Channel C3.
Содержание KD-34XBR2 - 34" Hdtv Fd Trinitron Wega
Страница 77: ...74 RA 5A Chassis Board Layout ...
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