Hitachi DV-P250U Service Manual page 14

Filter circuit eliminates high frequency components of analog video signals output from video encoder.
Afterwards in S2 processor circuit DC voltage is superposed on C signals then output 3 types of video signals:
composite video signals, Y/C(S2) video signals and YP
(PG2201).
The following is a description of video circuit along signal flow:
MULTIPLEXER
S E C T O R
D E M U L T I P L E X E R
P
(2~9)
U P S A M P L E
C O N V E R T E R
C L K
(48)
VIDEO ENCODER ADV7172 (IC2202)
1. MULTIPLEXER SECTOR
It transforms input digital video stream (Input at 2~9 pins) in 8bit parallel data then separates them in Y
data and C /C
B R
2. CONVERTER SECTOR
It generates various internal timing signals with the synchronous signal as standard by adding
synchronous signals generated in IC to Y data, according to the conditions set in the internal register or by
adding BURST signals to C
decoder (Output at 14,15 pins). In addition, when power is turned ON, RESET signal (Input of L level at 44
pin) is input to reset the register in IC.
Moreover, writing in the internal register (presetting) is done via I2C BUS ( 20,21 pins).
3. ENCODER SECTOR
The following 1~3 data are inserted in VIDEO DATA according to preset conditions in the internal register:
a. Closed caption
NTSC Mode: 21 lines and 284 lines/ PAL Mode: 22 lines and 335 ines.
b. CGMS (Copy Guard Management System)
20 lines and 280 lines of NTSC.
c. Macrovision Copy Prevention System
Finally it generates DIGITAL INTENSITY DATA, DIGITAL CHROMA DATA, and DIGITAL
COMPOSITE DATA.
Chapter 1
Block Diagram of VIDEO ENCODER B1865A (IC2202) interior
RESET SDA/SDL
(44) (21,20)
2
I C
I N T E R F A C E
CONVERTER
SECTOR
Y
S Y N C
A D D E R
B U R S T
C /C
B R
A D D E R
B L A N K H/V SYNC OUT
(16) (14/15)
data and changes simultaneously the rate (6.75MB/S->13.5MB/S).
/C data. At the same time it outputs these synchronous signals to A/V
B R
P /RGB to RJK substrate via 17P connector
B R
2
I C B U S
ENCODER SECTOR
C L O S E D
C A P T I O N
C G M S
M A C R O V I S I O N
C H R O M A
E N C O D E R
Y/C MIX
V O L T A G E R E F E R E N C E
(22/23/36/37/38)
Y (33)
C (29)
CVBS (35)
D A C
Y/G (28)
P /B (25)
B
P /R (24)
R
D/A
C O N V E R T E R
S E C T O R
11