Philips LC7.2E Service Manual page 88

EN 88 9. LC7.2E LA
9.3 DC/DC converters
A switch generates the +5.2 V (+5V_SW) from the +5.2 V
(+5V_STANDBY) supply voltage. For LCD sets, this switch is
mounted on-board the SSB. For PDP sets, this switch is
mounted on the Power Supply Panel. This results in the
+5V_STANDBY (and +5V_SW for PDP sets) voltage(s),
coming from the Power Supply Unit, is (are) used as input for
the on-board DC/DC converters.
They deliver the following voltages to the board:
• +3.3 V (+3V3_STBY)
• +5.2 V (+5V_SW) (only for LCD sets)
• +1.8 V (+1V8S_SW)
• +34 V (+VTUN)
• +3.3 V (+3V3_SW)
• +3.3 V (+3V3_MOJO)
• +1.2 V (+1V2_MOJO)
An overview can be found in figure "DC-DC converter block
diagram".
Figure 9-4 DC-DC converter block diagram
The +5 V switch, needed for the switch voltages, is for LCD
sets physically mounted on the SSB, whereas for the PDP sets
it is physically mounted on the PSU board.
9.4 Front-End
This chassis uses different tuners depending on the region. An
overview of region-dependency can be found in table "Tuner
diversity".
Table 9-1 Tuner diversity
Region Tuner
Europe TD1316AF
UV1318S
AP UV1316E
China TEDE9
Latam UV1338
The TD1316AF hybrid tuner used, is capable of receiving both
analogue and digital (DVB-T) signals. For the application in this
chassis see figure "Tuner IF diagram".
Circuit Descriptions, Abbreviation List, and IC Data Sheets
9.4.1
(n.a. for LC7.xH)
(n.a. for LC7.xH)
(n.a. for LC7.xH)
G_16860_063.eps
270707
Type
Hybrid
analogue
analogue
analogue
analogue
Video
SAW filter
Audio
Tuner
SAW filter
RFAGC
Supply
I 2 C
Digital IF
+5V/+33V
36.16MHz
4MHz
IF AGC
Figure 9-5 Tuner IF diagram
While receiving analogue signals, the signal coming from the
tuner is fed to the IF demodulator (through the SAW filters) and
then passed to the Trident Video Processor.
While receiving digital signals, the signal coming from the tuner
is fed to the channel decoder, to the MPEG decoder and then
to the Trident Video Processor.
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
to be 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
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
CVBS
IF Demodulator
2 nd SIF
RF AGC_analogue
RF AGC_digital
I 2 C_analogue
Switch IC
I 2 C_digital
G_16860_054.eps
020207
Region Video/Audio
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