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Circuit Description
—
a
".
. .
L-
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1-1. Video signal routing
Video signals output from IF pack are input to AV
switching IC (TA8747N). In this IC, they are switched to
AV signals. Colour. Y or composite signals output from
TA8747N are input to Colour Decoder & H/V Drive IC
(TDA9160) and Y signal is input to the Teletext Decoder.
All functions of TDA9160 are controlled by 12CBus lines
(SCL:Serial Clock/ SDA:Serial Data) of CPU. Y signal
output from TDA9160 is input to Y Feature IC (CXA
1420P) for the aperture control and black expand and
input to the velocity circuit. Y signal output from CXA
1420P is input to Video Controller IC (TDA4685). Colour
differential signals (R- Y/B- Y) demodulated byTDA9160
are input to 1H delay IC (TDA4661 ) as 1H delay and
matrix and
output
to TDA4685
as
proper
colour
differential signals. In TDA4685, colour differential signals
are converted to RGB signals, RGB signals from Teletext
decoder or CPU are super- imposed on them, and RGB
signals are output to RGB Drive IC (TDA6101Q/N2). CXA
1420P and TDA4685 also are controlled by 12C Bus lines.
1-2.
Audio
signal
routing
SIF signals output from IF pack are input to A2 stereo
decoder and NICAM stereo decoder. Stereo signals
detected by both decoders are input to AV switching
IC(TDA8747N). After switching to external audio signals
in this
IC, they
are
input to Sound
Selector
IC
(MC140538CP) as selecting an L channel, an R channel
or both channels.
Audio
signals
output
from
MC
140538CP are input to the Surround IC as mixing
surround signals in surround mode. Output signals are
input to Audio Control
IC (AN5836). Bass, treble,
balance and volume control is applied to signals, which
are amplified by Audio Output IC (LA4720), and output to
the speakers.
2. CPU (IC801) Pin Description
Pin 1: Oscillator for OSD (in)
Pin 2: Oscillator for OSD (out)
Pin 3: ABL voltage (in)
Ov- 5V
Pin 4: Brightness sensor (in)
Ov- 5V
Pin 5: Remote control input (active low)
Pin 6: Tuning voltage (out)
Pin 7: Band data (out)
Pin 8: Band data (out)
Pin 9: AFT input (1)
L:No signal
Pinl O:AFT input (2)
L: No signal
Pinl 1: AFT ON/OFF (out)
L: AFT ON
Pinl 2: Picture (TEXT) ON (in)
L: TEXT/TV mixed mode
–2–
Pin13: 12C BUS switching (out)
H: Normal
Pinl 4: RGB IGNOR output
H: IGNOR ON
Pinl 5: Woofer ON/OFF output
H:Woofer ON
Pinl 6: Not used
Pinl 7: Forced time base input
L: Forced time base is input (Factory mode)
Pinl 8: Setting to factory mode tin)
L: Factory mode
Pinl 9: Overload protector input
L: ProtectorON
Pin20: SCART option switch input
L: No SCART
Pin21: 12C Bus (SCL: Serial Clock)*
Pin22: 12C Bus (SDA: Serial Data) *
'To control TDA91 60, TDA4685,
NICAM decoder]
CXA
Pin23: Load output for DAC (Digital Analo
Pin24: TEXT DLIM (out)
Pin25: Clock output for DAC
Pin26: DAC & TEXT Data (out)
Pin27: Ground
Pin28: Not used
Pin29: RESET (in)
Pin30: Oscillator input for CPU (4MH2)
Pin31: Oscillator output for CPU (4MH2)
Pin32: Ground
Pin33: Power ON/OFF (out)
H:Power ON
Pin34: Power error output
H: Normal, H/L switching: Error
Pin35: TV/AV switch 2 (out)
Pin36: TV/AV switch 1 (out)
=
420P and
Iue Converter)
Pin37: SCART 8pin input
H to L: Switched to AV3
Pin38: Stereo control output 3
Pin39: Stereo control output 2
Pin40: Stereo control output 1
TV mode
Stereo
Main(A)
Sub(B) Mono Forced Mono
Pin 38
L
H
L
H
H
Pin 39
L
L
H
L
L
I
I
lPin 40 I
L
L
H[H
H
AV mode
Stereo Left(A)
Right(B)
Mono
Pin 38
L
H
L
H
Pin 39
L
L
H
Lor H
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