Sony KDP-51WS550 Training Manual page 32

Reference Figure 5-1
All video signals from the Main Tuner, Sub Tuner, Q-box (ATSC Tuner, Memory Stick, and I-Link) and Video
Inputs 1-7 are first fed into the AV Switcher (IC1501).
The Main Video coming from the Main Tuner, Q-Box or Video 1-7 is directed to the A/D converter (IC3101) to be
digitized.
If the Main video signal is anything other then 1080i (HDV), it will go through the DRC circuit (IC3201) and then
to the MID circuit (IC3301). The signal must be up-converted to 31.5KHz in the DRC, and then up-converted
again to 33.75KHz in the MID circuit.
If the Main video signal is 1080i format, it will go directly to the MID circuit (IC3301). There is no processing
performed on the 1080i signal by the MID circuit as it is basically a fed-through to the CRT drive circuits.
Table 5-2 gives the various video formats and the associated horizontal scan rate. The natural scan rate for this
chassis is the HD scan rate of 33.75KHz. The text following the table gives the basic path that each format must
follow to be up-converted to the HD scan rate.
Input Signal
Standard NTSC 480i
High Resolution 480p
High Resolution 720p
High Resolution 1080i
The following is a description of the signal flow for each standard listed in Table 5-2:
•
15.734KHz input: DRC circuit up-converts to 31.5KHz and MID circuit up-converts to 33.75KHz.
•
31.5KHz input: MID circuit up-converts to 33.75KHz.
•
33.75KHz input: XBR, HV pass through MID; HS bypass MID circuit.
•
45KHz input: MID circuit down-converts to 33.75KHz.
The Sub video path bypasses the A/D (IC3101) and DRC (IC3201) circuits and is applied directly to the MID
circuit (IC3301). The Sub signal is applied to an A/D circuit internal to the MID circuit (IC3301) where it is
digitized.
The MID circuit then applies the video to a D/A converter (IC3303) to be converted back to an analog signal,
which is then applied to the Y/C CRT Drive or Video Processor (IC0401). The analog video signal then drives the
video amps and the CRT.
The various OSD signals, such as the User Main Menu, PJED Menu (Service Mode), Digital Channel Menu,
Service Mode, Closed Caption and Channel number are produced by either the Main Microprocessor, PJED
Microprocessor or the ATI Microprocessor (in Q-Box).
OSD Signals
Main Microprocessor:
•
User Menu
•
All Other Service Mode Items (Excluding PJED Items)
•
Closed Caption
Table 5-2 - Input Signal Standard and Horizontal Frequency
Horizontal Frequency
15.534KHz
31.5KHz
45KHz
33.75KHzz
30
5. AX-1 Video Processing