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8
LC-13B2H/M
LC-15B2H/M
LC-20B2H/M
LC-15B2H/M
LC-20B2H/M
3-2. Audio signal processing circuit
The audio signal processing circuit is mainly composed of a 1-chip digital audio signal processing circuit (IC3304),
an active filter circuit (IC3301-IC3303) and an audio amplifying IC (IC3305).
Controlling of IC3304 is all under microprocessor control (I
an active filter circuit (IC3301-IC3303) and an audio amplifying IC (IC3305).
Controlling of IC3304 is all under microprocessor control (I
2
C bus control, port control).
The SIF signal sent from the tuner is amplified in the SIF amplifying circuit composed of Q3201 and Q3202 and
is inputted to pin (87) (ANA_IN+ terminal) of IC3304. Then, after being A/D-converted, it is subjected to FM
detecting and sound multiplex decoding (NICAM/IGR) in digital signal processing.
The TV audio signal and the audio input signal for three systems (video: 2, component: 1) A/D-converted in
IC3304 are switched in the IC, subjected to volume controlling and equalizer correction (for acoustic character-
istic correction) and then outputted from pins (27) and (28) as analog signals after being D/A converted.
The audio signal outputted from pins (27) and (28) of IC3304 is subjected to acoustic characteristic correction in
the active filter circuit composed of IC3301, IC3302 (used in 13/15 only) and IC3303, audio-amplified in IC3305
and then outputted through J3500 (headphone jack) to the speaker.
The analog audio signal outputted from pins (36) and (37) of IC3304 is subjected to V2 audio I/O switching in
IC3501 and outputted from the AV2 terminal (AV2 terminal output mode).
is inputted to pin (87) (ANA_IN+ terminal) of IC3304. Then, after being A/D-converted, it is subjected to FM
detecting and sound multiplex decoding (NICAM/IGR) in digital signal processing.
The TV audio signal and the audio input signal for three systems (video: 2, component: 1) A/D-converted in
IC3304 are switched in the IC, subjected to volume controlling and equalizer correction (for acoustic character-
istic correction) and then outputted from pins (27) and (28) as analog signals after being D/A converted.
The audio signal outputted from pins (27) and (28) of IC3304 is subjected to acoustic characteristic correction in
the active filter circuit composed of IC3301, IC3302 (used in 13/15 only) and IC3303, audio-amplified in IC3305
and then outputted through J3500 (headphone jack) to the speaker.
The analog audio signal outputted from pins (36) and (37) of IC3304 is subjected to V2 audio I/O switching in
IC3501 and outputted from the AV2 terminal (AV2 terminal output mode).
AV1
S-VIDEO
INPUT
AV2
INPUT
OUTPUT
COMPONENT
INPUT
AUDIO
IN/OUT
SWITCH
IC3501
Q3500
AUDIO
DECODER
(MSP)
IC3304
L2, R2
DL, DR
L1, R1
I
2
C
AUDIO
FILTER
IC3301
IC3303
IC3302
Model
13/15
DC POWER
AUDIO
AMPLIFIER
IC3305
HEAD
PHONE
JACK
SP-L
SP-R
Fig. 3-2. Video signal processing circuit
3-3. Video signal processing circuit
The video signal processing circuit is a multi video system that is mainly composed of a digital video signal
processing IC (IC801).
The TV video signal sent from the tuner and the V1 video input signal and V2 video input signal inputted through
each input terminal are switched in IC402 and inputted to pin (73) of IC801. The Y/C signal inputted to the S
terminal is inputted to pins (71) and (72) of IC801.
The AV2 terminal is capable of I/O switching and controlled by Q3501 thru Q3505.
processing IC (IC801).
The TV video signal sent from the tuner and the V1 video input signal and V2 video input signal inputted through
each input terminal are switched in IC402 and inputted to pin (73) of IC801. The Y/C signal inputted to the S
terminal is inputted to pins (71) and (72) of IC801.
The AV2 terminal is capable of I/O switching and controlled by Q3501 thru Q3505.
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