Panasonic LC4.8E AA Service Manual page 93

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Circuit Descriptions, Abbreviation List, and IC Data Sheets
Table 9-1 Models and picture quality
Model
42PF7420/10
37PF7320/10
37PF5320/10
CVBS
Pb, Pr
PIXEL PLUS HERCULES
CVBS
Pb, Pr
DIGITAL
HERCULES
CRYSTAL CLEAR
R, G, B
CRYSTAL CLEAR HERCULES
Figure 9-2 Block diagram of the internal building blocks
The Genesis GM1501 Malibu Scaler IC can receive two video
input signals: SDTV (directly from Hercules or via Columbus),
DVI (from an external DVI source), or PC (from external
computer).
After the video processing, the digital data is sent 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 EEPROM, or NVM (Non Volatile Memory) is 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 Input/Output
The I/O is divided over two parts: Rear I/O and Side I/O. The
rear has two SCART inputs, a PC/DVI-I input (VGA to DVI-I via
an external adaptor) and an Audio input. The side has a CVBS
and Y/C (SVHS) input, combined with L+R audio inputs, and
has also a headphone output.
EXT1: The input of SCART1 is CVBS + RGB + L/R and the
output is the video (+ sound) signal from the tuner
(SC1_CVBS_RF_OUT).
EXT2: The input of SCART2 is Y/C + CVBS + L/R. The output
signal is CVBS_SC2_MON_OUT (+ sound).
SCART2 is meant for VCR and has therefore some additional
signals in relation to EXT1 but no RGB: it has the possibility for
Y/C_in: Y_in on pin 20 and Chroma_in on pin 15.
The selection of the external I/O's is controlled by the Hercules.
PC in (DVI-I, or VGA via external VGA to DVI-I adaptor): This
input is directly going to the Scaler IC. See paragraph "Video:
Scaler Part".
Picture quality
Pixel Plus
Pixel Plus
Digital Crystal Clear
ADC COLUMBUS SCALER EPLD
ADC COLUMBUS SCALER
SCALER
9.4 Tuner and IF
A Philips UV1318 Tuner is used in the TV board. The SIF
signals are decoded by the Hercules. Tuning is done via I
9.4.1 Video IF Amplifier
The IF-filter is integrated in a SAW (Surface Acoustic Wave)
filter. One for filtering IF-video (1104, in some models: 1105)
and one for IF-audio (1106). The type of these filters depends
LVDS
on the standard(s) that has/have 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
LVDS
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
LVDS
is wrong. The AGC-setting could also be mis-aligned if the
F_15270_008.eps
240505 picture deforms with perfect signal; the IF-amplifier amplifies
too much.
LC4.8E AA 9. EN 93
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