Philips EM3E, Руководство по обслуживанию, Страница: 48 / 120

Circuit Descriptions and Abbreviation List GB 100 EM3E 9.
adjusted via the service menu ‘IF AFC’. If the alignment is
correct, the displayed frequency in the installation menu is
the same as the applied frequency from a generator. The
external coil L5408 connected between pins 7/8 is used as
reference.
The demodulated IF-video signal is available at pin 10 of the
HIP. In this video signal, there is a rest of the sound carrier,
which is filtered out by the sound trap 1407.
Then the signal is again fed to the HIP on pin 12, where the
group delay is corrected, dependent on the standard that is
received.
The CVBS-signal is available at pin 13 for further processing
in the set. Via TS7322, the signal is supplied to EXT1
(monitor out) and again back into the HIP (pin 14) to the
source/record selection.
To realise Quasi Split Sound (QSS), the IF-signal is fed to the
HIP on pin 63/64 via SAW-filter 1405. The FM (or AM for L-
norm) -modulated signal is available on pin 5 and is fed to the
audio demodulator MSP34xx (7651).
9.6 Video: High-end Input Processor (HIP,
diagram B2))
In the EM3E, the HIP TDA932xH is used, which contains the
following functions:
•
IF demodulation.
• Group delay correction.
• AFC signal generation, used to track drifting transmitters.
• Sound carrier re-generation (SIF).
• AM demodulation.
• Sync acquisition, delivering H
A
and V
A
.
• Switching off IF-filtering.
9.6.1 Inputs
The HIP has various inputs:
•
Full matrix switch with:
–
2 CVBS inputs
– 2 Y/C (or additional CVBS) inputs
– 1 CVBS front end input.
• Two RGB inputs and 2 status-inputs
The input signals from the Front I/O are fed to the HIP, and
front detection is fed to the OTC.
•
EXT1 is full SCART: thus CVBS and RGB. The RGB-
selection is done in the HIP.
• EXT2 is meant for VCR and has therefore some
additional signals in relation to EXT1 but no RGB. EXT2
has also the possibility for Y/C_in and Easylink-Plus
(P50). Y_in is with pin 20 and Chroma in with pin 15.
Easylink is handled via pin 10 of the SCART and this is a
bi-directional communication.
• EXT3 is meant for CVBS input only.
9.6.2 Outputs
One can select three, separate switchable, outputs:
•
1 YUV-output, which is fed to the PICNIC
• 2 CVBS outputs, one for Teletext Dual Screen and the
other for output to EXT2 to have WYSIWYR (What You
See Is What You Record).
9.6.3 I/O Switching
The external signals are fed directly to the I/O part of the HIP
with status from pin 8 of SCART. On the HIP there are two
status inputs available (pins 15, 17) with two voltage levels:
•
4:3 -> 2.2 V
• 16:9 -> 5.5 V
9.6.4 P50
Easylink supports the next features:
•
Signal quality and aspect ratio matching
• One touch play
• One touch text
• Pre-set download
• WYSIWYR
• Automatic Standby
With Easylink-Plus (P50+) is added:
•
Country and language installation
• System Standby
• Intelligent set top box features
• NexTView download
• Timer record control
• VCR control feature
9.6.5 Video Processing
The sandcastle-pulse of the HIP is not used for
synchronisation. The HOP will generate synchronisation
signal derived from the feature box (PICNIC) signals. If a
VCR is connected, there is also an automatic correction for
MacroVision. This is active for the external sources and the
pre-sets 0, 90-99.
The HIP itself (no external voltage) controls the Y/C switch in
the HIP.
The chrominance decoder in the HIP is full multi-standard:
PAL/SECAM/NTSC.
Two different crystals can be connected to the pins 54 & 57
without any alignment. The crystals are also used as a
reference for the synchronisation. A digital control circuit that
is locked to the reference signal of the colour decoder
determines the start-up of the sync. The original one may
only replace this crystal. If just a crystal is taken, the internal
capacitance will be different and the effect will be that there
is no colour.
In the HIP a sync separation circuit is integrated; the HIP
delivers the HA
50
and VA
50
to the PICNIC.
9.7 Video: Feature Box (PICNIC and FALCONIC,
diagram B3)
9.7.1 Introduction
The basic function of the Feature box (FBX6) is picture
improvement, and depending on the version, several scan
conversion methods are possible. The PICNIC (SAA4978H)
is the central key component.
In the EM3E-chassis, the feature-box is integrated on the
SSB.
The PICNIC is used for the 100Hz conversion and has the
following functions:
•
The ADC.
• The DAC.
• The 100 Hz conversion.
• Dual screen compression
• The Panorama mode.
• Automatic Aspect Ratio Adaptation (AARA)
• Colour Transient Improvement (CTI)
• The contrast improvement (Dynamic Contrast).
All these functions are integrated in one IC: SAA4978H, 160
pins QFP
9.7.2 ADC/DAC
Analogue to Digital conversion is done with three identical 9-
bit ADC's.
Digital to Analogue conversion uses three identical 10-bit
DAC's.
In the PICNIC there are three 9 bits ADCs present for Y,U,V.
For digitising the Y (luminance), 9 bits are used (to realise a
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