Hitachi DV-P505E, Service Manual

Page: 13 / 58

Chapter 1 7
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
B
P
R
/RGB to RJK substrate via 17P connector
(PG2201).
The following is a description of video circuit along signal flow:
VIDEO ENCODER ADV7170 (IC2202)
1. MULTIPLEXER SECTOR
It transforms input digital video stream (Input at 1~4, 38~42 pins) in 8bit parallel data then separates them
in Y data and C
B
/C
R
data and changes simultaneously the rate (6.75MB/S->13.5MB/S).
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
B
/C
R
data. At the same time it outputs these synchronous signals to A/V
processor (Output at 15,16 pins). In addition, when power is turned ON, RESET signal (Input of L level at
22 pin) is input to reset the register in IC.
Moreover, writing in the internal register (presetting) is done via I2C BUS ( 23,24 pins).
3. ENCODER SECTOR
The following a~c 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 283 lines of NTSC.
c. Macrovision Copy Prevention System (Anti Taping)
Finally it generates Analog Colorstripe, AGC Palses, Pseudo-sync, EOF Back Porch Pulses.
d. D/A CONVERTER (DAC)SECTOR
Constituted of 10bit DAC, it transforms DIGITAL VIDEO DATA to ANALOG VIDEO DATA for output.
I
2
C
I N T E R F A C E
S Y N C
A D D E R
B U R S T
A D D E R
C L O S E D
C A P T I O N
Y/C MIX
C H R O M A
E N C O D E R
M A C R O V I S I O N
C G M S D E M U L T I P L E X E R
C O N V E R T E R
U P S A M P L E
D A C
I
2
C B U S
ENCODER SECTOR
CONVERTER
SECTOR
Y
C
B
/C
R
P
(1~4, 38~42)
RESET
(22)
SDA/SDL
(24, 23)
V O L T A G E R E F E R E N C E
(25/33/34)
D / A
C O N V E R T E R
S E C T O R
Y (27)
C (26)
CVBS (32)
Y/G (27)
P
B
/B (31)
P
R
/R (26)
B L A N K
(17)
H / V S Y N C O U T
(15/16)
C L K
(44)
M U L T I P L E X E R
S E C T O R
Block Diagram of VIDEO ENCODER ÃDV7170 (IC2201) interior