Philips LC7.1E Service Manual page 76

EN 76 9. LC7.1E LA
9.4.1 Video IF Amplifier
The IF-filter is integrated in a SAW (Surface Acoustic Wave)
filter. One for filtering IF-video (item 1102) and one for IF-audio
(item 1103). The type of these filters depends on the
standard(s) received (region-dependency). Some filters can be
switched to another standard, what makes them suitable for
applications in multi-standard platforms. An overview of the
SAW filter diversity can be found in table "SAW filter diversity".
Table 9-2 SAW filter diversity
SAW filter Switching Y/N Region Video/Audio
OFWK3953M No
OFWK9656M Yes
OFWK7265L Yes
OFWK9361L No
OFWK3956L No
OFWK3955L No
OFWK9352L No
OFWM1967L No
Switching is done by the microcontroller via SAW_SW. In table
"SAW filter switching" is explained how to address the different
system standards.
Table 9-3 SAW filter switching
Region SAW_SW
Europe 1
0
AP 1
0
China 1
0
LATAM n.a.
The hybrid tuner TDA1316AF, used in Europe sets, needs to
be switched between digital and analogue mode. This is done
by the microcontroller via DVB_SW. Refer to table "Hybrid
tuner digital/analogue switching" for details.
Table 9-4 Hybrid tuner digital/analogue switching
Region DVB_SW
Europe 1
0
The pin assignment of all analogue tuners is equal and can be
found in table "Pin assignment analogue tuners".
Table 9-5 Pin assignment analogue tuners
Pin
number Description
1 RF AGC voltage
2 n.c.
2
3 I C-bus address select 0
4 SCL
5 SDA
6 n.c.
7 supply voltage
8 n.c.
9 tuning supply voltage
Circuit Descriptions, Abbreviation List, and IC Data Sheets
Europe Video
Europe Audio
AP Video
AP Sound
China Video
China Video
China Audio
LATAM Video/Audio
System
L'
other systems
B/G, D/K, I
M/N
B/G, D/K, I
M/N
M/N
Mode
analogue reception
Digital reception
DC voltage (V)
3.3 - 4.5 (weak or no
signal) < 3.3 (strong signal)
0 to 3.3
0 to 3.3
5 ±0.25
33
Pin
number Description
10 n.c.
11 TV IF output
The pin assignment of the hybrid tuner can be found in table
"Pin assignment hybrid tuner".
Table 9-6 Pin assignment hybrid tuner
Pin
number Description
1 n.c.
2 RF AGC voltage
2
3 I C-bus address select 0
4 SCL
5 SDA
6 4 MHz reference
output
7 supply voltage
8 broadband IF output
9 IF AGC voltage
10 narrowband IF output
11 narrowband IF output
9.4.2 Automatic Gain Control
In the LC7.2x chassis (digital sets), the automatic gain control
depends on if the set is receiving a digital or an analogue
signal. During analogue reception, the hybrid tuner receives an
external AGC voltage, coming from the demodulator, to
perform automatic gain control. During digital reception, no
external AGC voltage is used but the tuners internal AGC loop
is used.
In the LC7.1x chassis (analogue sets), the tuner receives an
external AGC voltage, coming from the demodulator, to
perform automatic gain control.
9.5 Video Processing
The video processing is completely handled by the Trident SVP
CX32 video processor which features:
• CVBS-input for analogue signals
• RGB-input for digital (DVB-T) signals
• Motion and "edge-adaptive" deinterlacing
• Integrated ADC
• Built-in 8-bit LVDS transmitter
• Colour stretch
• Skin colour enhancement
• 3D Digital Comb Video Decoder
• Interlaced and Progressive Scan refresh
• Teletext decoding
• OSD and VBI/Closed Caption.
DC voltage (V)
DC voltage (V)
3.3 - 4.5 (weak or no
signal) < 3.3 (strong signal)
0 to 3.3
0 to 3.3
5 ±0.25
0 to 3