Hitachi 46W500 Training page 37

DP-3X CHASSIS VIDEO SIGNAL PATH NTSC EXPLANATION
(See Video Signal Path-NTSC Diagram for details)
It's important to note that this Chassis horizontal deflection operates at 33.75Khz at all times. Even though this is more than
twice as fast as NTSC, the set will still display NTSC video with no problem. This is accomplished by the Flex Converter.
The Flex Converter will manipulate any input, be it NTSC, Component 480i, 480P, 720P to the appropriate Horizontal Fre-
quency rate of 33.75Khz. This makes this chassis very versatile in it's application. Note: 1080i is already 540 in the native
state. In this case, true 1080i does not need to be routed through the Flex Converter. It's routed directly into the Rainforest IC.
The following will discuss the signal flow as show in the above listed Circuit Diagram.
TUNER INPUTS:
These sets utilizes two tuners, (DP-36 and DP-38 also have an ATSC Digital Tuner UD2002) one for the Main picture U301
and one for the PinP (Sub) picture U302. U301 is an intergraded tuner with RF front end, IF decoding, Audio Decoding to Lt/
Rt. The tuner communicates with the Microprocessor via I2C bus. (See Microprocessor Data Communications Circuit Dia-
gram for details).
The PinP tuner U302 is also an intergraded tuner, however the Audio output is mono only.
Both tuners output their respected composite video via pin 18.
•
U301 Main Tuner Output pin 18 to PST1 connector pin 50, to the Selector IC IV01 pin 63.
•
U302 PinP (Sub) Tuner Output pin 18 to PST1 connector pin 45, to the Selector IC IV01 pin 60.
(DP-36 and DP-38 ONLY):
•
UD2002
◊
LUMINANCE: The ATSC (QAM) Tuner (Digital Tuner) Outputs DM Y from pin 7 to the PST1 connector
pin 31, to the Selector IC IV01 pin 3.
◊
CHROMINANCE: The ATSC (QAM) Tuner (Digital Tuner) Outputs DM C from pin 5 to the PST1 connector
pin 32, to the Selector IC IV01 pin 5.
These inputs are used while viewing an SDTV or HDTV source, so that there will be an output from the Monitor
Video Jack.
NOTE: The DP-36-38 have a Digital Tuner (ATSC-8VSB and Cable QAM Tuner) is in the Digital Module. This
Digital Module is also the input/output access for IEEE1394. (See the ATSC Block Diagram which is coming up
after the Component, OSD and NTSC Diagram). Even though this explanation is related to NTSC, the ATSC tuner
is involved because of the Video Output called (Monitor Out) jack. When ATSC or QAM is viewed, the monitor
out must have video output for recording purposes. This is accomplished by the ATSC (Digital Tuner) having a Y/C
output sent to the NTSC circuit for this purpose.
AUXILIARY INPUT:
This chassis utilizes 5 separate inputs plus a newly added input called DVI. The following will break down those input routes
to the Selector IC IV01. (Some models will also have a built in DVD player for 6th input).
(1) INPUT 1: This input is only for Component Inputs Y Pr/Pb (31.5Khz to 33.75Khz ATSC) and will not accept Compos-
ite on the Y input. Input one's Y line is input directly into IV04 pin 9 (Y Pr/Pb Selector), not for NTSC.
(2) INPUT 2: This input will accept Component Inputs Y Pr/ Pb (31.5Khz to 33.75Khz ATSC) or Y Cr/Cb (15,735Hz.
NTSC). It will also accept Composite Video input as long as there is no Pr plug inserted. Input 2 is routed into the Selec-
tor IC IV01 pin 30.
(3) INPUT 3: This is NTSC composite input only. It also has an accompanying S-Input. Remember that the S-Input takes
priority over composite input, when S-Input is active. Input 3 is routed into the Selector IC IV01 pin 15. The S-Input
inputs are pin 17 for Y (Luminance) and pin 19 for C (Chroma). When an S-Jack is inserted into the plug, an internal
mechanical switch is activated which produces a low to the Selector IC IV01 pin 21 and the Selector IC notifies the Mi-
croprocessor that and S-Jack is installed.
(4) INPUT 4: This is NTSC composite input only. It also has an accompanying S-Input. Remember that the S-Input takes
priority over composite input, when S-Input is active. Input 4 is routed into the Selector IC IV01 pin 8. The S-Input in-
puts are pin 10 for Y (Luminance) and pin 12 for C (Chroma). When an S-Jack is inserted into the plug, an internal me-
chanical switch is activated which produces a low to the Selector IC IV01 pin 14 and the Selector IC notifies the Micro-
processor that and S-Jack is installed.
(5) INPUT 5: On the Front Control Panel. This is NTSC composite input only. It also has an accompanying S-Input. Re-
member that the S-Input takes priority over composite input, when S-Input is active. Video Input 5 is routed through the
PFT connector pin 2, into the Selector IC IV01 pin 22. The S-Input inputs are routed through the PFT connector pin 7
for Y and pin 9 for C, into the Selector IC IV01 pin 24 for Y (Luminance) and pin 26 for C (Chroma). When an S-Jack is
inserted into the plug, an internal mechanical switch is activated which produces a low through the PFT connector pin
11, into the Selector IC IV01 pin 28 and the Selector IC notifies the Microprocessor that and S-Jack is installed.
(Continued on page 03-02)
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