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EN 76
9.
The PLL tuner delivers the IF-signal, via audio & video SAW-
filters, to the Video Signal Processor with FLASH embedded
TEXT/Control/Graphics m-Controller (TCG m-Controller) and
US Closed Caption decoder. TDA120x1 (item 7011, also called
Hercules). This IC has the following functions:
•
Analogue Video Processing.
•
Sound Demodulation.
•
Audio Interfaces and switching.
•
Volume and tone control for loudspeakers.
•
Reflection and delay for loudspeaker channels.
•
Micro Controller.
•
Data Capture.
•
Display.
The Hercules has one input for the internal CVBS signal and a
video switch with 3 external CVBS inputs and a CVBS output.
All CVBS inputs can be used as Y-input for Y/C signals.
However, only 2 Y/C sources can be selected because the
circuit has 2 chroma inputs. It is possible to add an additional
CVBS(Y)/C input (CVBS/YX and CX) when the YUV interface
and the RGB/YPRPB input are not needed. The I/O is divided
over two parts: Rear I/O and Side I/O. The rear has two AV
inputs with CVBS, Y/C and YUV, a PC (VGA) input, and an
HDMI input. The side has a CVBS and Y/C (SVHS) input.
The video part delivers the RGB signals to the Scaler IC.
The Genesis GM1501 Malibu Scaler IC can receive different
video input signals: SDTV (from Hercules), DVI/HDMI (from
external DVI/HDMI source), or PC (VGA) (from external
computer).
After the video processing, the digital data is send via a Low
Voltage Differential Signalling bus to the LCD panel. LVDS is
used to improve data speed and to reduce EMI significantly.
2
There are two I
C lines and two interrupt and communication
lines (TV_IRQ and TV_SC_COM) for the Scaler control. The
Scaler communicates with the Hercules as a slave device. To
avoid buffer overflow at the Scaler side, the TV_SC_COM line
provides the necessary hardware flow control. To allow bi-
directional communication, the Scaler can initiate a service
interrupt-request to the Hercules via the TV_IRQ line.
The Hercules, and EEPROM are supplied with 3.3 V, which is
also present during STANDBY.
The EEPROMs, or NVMs (Non Volatile Memory) are used to
store the settings.
The sound part is built up around the Hercules. The Source
Selection, Decoding and Processing are all done by the
Hercules.
Power supply input are several DC voltages coming from a
supply panel.
9.3
Power Supply LCD
See the FTL2.1 manual for a detailed description.
9.4
Input/Output
The I/O is divided over two parts: Rear I/O and Side I/O. The
rear has two AV inputs with CVBS, Y/C and YUV, a PC (VGA)
input, and an HDMI input. The side has a CVBS and Y/C
(SVHS) input.
AV1: The input of AV1 is CVBS + YUV + L/R.
AV2: The input of AV2 is Y/C + CVBS + L/R.
LC4.6U
Circuit Descriptions, Abbreviation List, and IC Data Sheets
PC (VGA) in: This input is directly going to the Scaler IC. See
paragraph "Video: Scaler Part".
HDMI in: This input is directly going to the Scaler IC. See
paragraph "Video: Scaler Part".
The selection of the external I/O's is controlled by the Hercules.
9.5
Tuner and IF (diagram A1)
A Philips UV13xx Tuner is used in the TV board. The SIF
signals are decoded by the Hercules. Tuning is done via I
9.5.1
Video IF amplifier
The IF-filter is integrated in a SAW (Surface Acoustic Wave)
filter. One for filtering IF-video (1328) and one for IF-audio
(1330). The type of these filters is depending of the standard(s)
that has to be received.
The output of the tuner is controlled via an IF-amplifier with
AGC-control. This is a voltage feedback from pin 31 of the
Hercules to pin 1 of the tuner. The AGC-detector operates on
top sync and top white level. AGC take-over point is adjusted
via the service alignment mode "Tuner" - "AGC". If there is too
much noise in the picture, then it could be that the AGC setting
is wrong. The AGC-setting could also be mis-aligned if the
picture deforms with perfect signal; the IF-amplifier amplifies
too much.
9.6
Video: TV Part (diagrams A1, A2, and A3)
The video processing is completely handled by the Hercules:
•
IF demodulator.
•
Chrominance decoder
•
Sync separator.
•
Horizontal & vertical drive.
•
RGB processing.
•
CVBS and SVHS source select.
It has also build in features like:
•
CTI.
•
Black stretch.
•
Blue stretch.
•
White stretch.
•
Slow start up.
•
Dynamic skin tone correction etc.
Further, it also incorporates sound IF traps and filters, and
requires only one crystal for all systems.
9.6.1
Histogram (YUV picture improvement) IC
The demodulated video-signal can be checked on pins 74, 75,
and 76 of IC7011 and is fed to pins 70, 71, and 72. In this path,
the Histogram IC TDA9171 is inserted.
This TDA9178 can control various picture improvements:
•
Histogram processing.
•
Color transient improvement.
•
Luminance transient improvement.
•
Black and white stretch.
•
Skin tone correction.
•
Green enhancement.
•
Blue stretch.
•
Smart peaking.
•
Video dependent coring.
•
Color dependent stretching.
Since the TDA9171 is connected to the Hercules, picture
improvement works only for signals that are routed through the
Hercules and not for signals directly connected to the Scaler.
2
C.
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