Hitachi C28W440N, Service Manual

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VIDEO PATH
In this chassis the TDA 8885 video-processor (IC200) is used. The filtered IF signals
are processed and sent as CVBS signal to the video switch IC (IC201). In IC201,
according to the software and user control, the output CVBS signal is selected
whether from the tuner, SCARTS, BAV, BAV or SVHS (or if exists DVD, DVB or
else). The video IF signals from the SAW filters are processed in the video-processor,
then sent as IF video output from pin 16. This output is again processed in the
processor as CVBS signal from pin 24. The switched CVBS signal from IC201 is then
processed as an input to pin 29. Then from pins 31/32/33 RGB signals are sent to the
CRT baseboard as outputs. If there is an SVHS source the input signals from back or
front SVHS jacks are input to pins 20/21 as chroma and luma respectively. If the TV
is with comb-filter, both the CVBS and SVHS signals are filtered in the comb-filter
IC (IC203). Then the outputs from IC203 are sent to video-processor.
SOUND PATH
The sound IF inputs (pins 8/9) are processed and sent as QSS output from pin 11 of
IC200 to pin 58 of audio-processor IC700 as input. The sources other then IF are
direct inputs to IC700. (SCARTS, FAV, BAV; pins 52/53/49/50/46/4743/44) These
sound signals are processed and sent as outputs to audio amplifier IC701 (When
Dolby Pro-logic or sub-woofer there are two audio-amplifiers.) or direct outputs from
SCARTS, BAV, LINE OUT, HEADPHONE or else. If there are much more
peripherals to give audio input, IC706 is used as a audio switch IC. In IC701, the
main right and left audio signals are amplified and then given to the speakers. If the
mute signal from the micro-controller comes, the amplifier is muted with hardware,
the sound processor with software as well.
R.G.B
The R.G.B signals from pins 7,11 and 15 of the SCART connectors (PL207) are fed
to the R.G.B input pins (41,42,43) of IC200.
R.G.B operation can be enabled by either taking pin 16 of the SCART connector high,
this high is fed to Pin 44 of IC200 or via the l²C bus the micro-controller sets IC200 to
forced R.G.B mode in which the video processor generates its own fast blank signal.
This puts the IC into external R.G.B mode and selects the inputs on pins 41,42 and 43,
overriding the video input on pin 24/29.
Note: when using R.G.B input the contrast, brightness and colour controls will still
operate
.
DEFLECTION CIRCUIT
All the sync signals and drive signals for the deflection part are sent from the video-
processor. A fly-back pulse is taken from pin1 of the FBT. The east-west (EW) signal
from pin 62 of IC200 feeds the EW circuitry and Q604, so the horizontal deflection is
enlarged and arranged according to the tube size. Sand (castle) signal from pin57 of
IC200 is used for vertical and horizontal synchronisation. The horizontal level is
driven by the horizontal-drive-out signal from pin 56 to Q600, through the TR600
horizontal transformer and finally the horizontal transistor Q602 is driven. FBT
(TR601) is driven with the B+ supply voltage from the SMPS pin20. The vertical
stage is processed by the vertical-deflection IC (IC600). The inverted and non-