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Figure 9-14
SAW-filter (pos. 1352) RESET = Low RESET = High
AP P/M (38.9MHz)
NTSC-M/N
China (38.0MHz)
NTSC-M/N
In order to display the external AV sources by the DW panel,
source selection circuit is incorporated on the panel. In
EM1A, 4 external AV sources are possible (AV1, AV2/S-
VHS1, AV3/S-VHS2 & YUV). The selection between these
sources is done by IC7401 HEF4053.
Note: When S-VHS is inserted from the rear, AV2 source will
be disabled. Likewise when S-VHS is inserted from the side-
AV. The YUV is fed directly to video processor IC7301. This
source selection is done internally by the IC.
The video processor IC7301 will decode the CVBS at pin-24
or pin-29 into YC signal and further process it into YUV signal
and output at pin-40, 45 & 46. The IC7301 internal FM
demodulator is used to produce mono audio and is available
at the pin-8 of IC7301. This audio signal PIP-AUDIO is fed to
the SSB sound processor as such that DW sound appeared
at the headphone
DW/PIP processing
IC7801 SAB9081 is a multi-standard PIP controller, which
can be used in double window or PIP applications. The YUV
from the video processor IC7301 is fed to pin-79, 81 & 83.
IC7801 will inserts YUV from the IC7301 with reduced size
into the main picture YUV source in PIP environment. The
main picture YUV is fed to pin-100, 2 & 98 respectively.
These signals are mainly used during the DW mode.
Inside IC7801, the conversion to the digital environment is
done on chip with ADCs. Processing and storage (1 MB
DRAM) of the video data is done entirely in the digital
domain. The conversion back to the analogue domain is
done by DACs. Internal clocks are generated by PLLs, which
lock on to the applied horizontal and vertical syncs from the
main & sub pictures. The main picture syncs are applied to
pin-70 (vert.) & pin-94 (hor.) and the sub picture syncs are
applied to pin-72 (vert.) and pin-87 (hor.).
For DW mode, the main picture is compressed horizontally
by a factor of two and directly fed to the output. After
compression, a horizontal expansion of two is possible for
the main picture. The sub picture is also compressed
horizontally by a factor of two but stored in memory before it
is fed to the outputs.
Post-processed YUV signals are fed to fast switching IC7803
TDA8601 pin-6, 7 & 8. In normal operation (w/o DW), the
main picture YUV signals (at pin-2, 3 & 4) are bypassed by
IC7803, and returned back to the main video processor.
When DW mode is active, the compressed YUV signals
(main & sub pictures) are used and fed to main video
processor. During the PIP mode, only sub-picture YUV
signals are used. The insertion control is made possible by
fast blanking signal from IC7801 pin-68.
Circuit descriptions and abbreviation list
CL06532045_072.eps
100500
PAL BG/DK/I
PAL BG/DK/I
EM1A
Power supplies
The power supplies used by DW panel are from the main
board 5V, 8V and 33V (for tuner only). The 5V is regulated to
+3.3V, +3V & +3VD by IC7802 LM317T. These voltages are
mainly used by DW processor circuitry. The 8V is mainly
supplied to IC7301 TDA888x IF + video processing circuitry
and also to fast switching IC7803.
9.
GB 95
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