Sharp LC-13C2E (serv.man2) Service Manual ▷ View online
5
LC-13B2H/M
LC-15B2H/M
LC-20B2H/M
LC-15B2H/M
LC-20B2H/M
3. GENERAL DESCRIPTION OF FUNCTIONS OF CIRCUITS IN EACH UNIT
MAIN UNIT
CIRCUIT
REF.No.
MAIN PARTS CODE
FUNCTION
Video circuit
IC801
VHIVPC3230D-1
Digital video signal processing
A/D converter, Color detection and decode
Image switching, Image control
Image quality correction, Contour correction
Component signal processing
4 Line Digital Comb Filter
CPU
IC2001
RH-IXA003WJZZQ
IC control, Channel selection control, Lamp error control
OSD, Remote control decode
Closed caption decode
V-Chip decode
LCD control
IC1201
RH-IX3378CEZZ
Liquid crystal timing control
Light control, OSD display
Vertical and horizontal reverse display control
PAL pixel skipping 7-6 line conversion, 8-6 bit conversion
IC1202
VHIPD485505-2
Memory for pixel skipping line conversion
IC1203
VHITC4W53U/-1
Gate control
IC1204
VHITC4024BF-1
Gate control
IC1205
VHITC4052BF1E
Gate control
Gray level circuit
IC1101
VHIMB8346BV-1
D/A converter
Gray level voltage generation
IC1102
VHINJM4565V-1
Dual operational amplifier
IC1103
Gray level voltage buffer
IC1104
IC1105
VHIBU4053V/-1
3-circuit 2-channel analog multiplexer
IC1110
Gray level voltage switching
IC1106
VHINJM4580V-1
Dual operational amplifier
IC1107
Gray level voltage buffer drive
IC1108
IC1109
VHINJM353M/-1
Dual operational amplifier
Common voltage buffer
6
LC-13B2H/M
LC-15B2H/M
LC-20B2H/M
LC-15B2H/M
LC-20B2H/M
CIRCUIT
REF.No.
MAIN PARTS CODE
FUNCTION
Tuner
TU3201
VTUVT2U5CD553
PLL channel selection, Video detection, Audio detection, AFT, AGC
Audio circuit
IC3304
RH-IX3371CEN1Q
Digital audio signal processing
SIF detection, NICAM/IGR detection and decode
Audio input switching, Equalizer, Volume control
A/D converter, D/A converter
IC3301
VHINJM4560M-1
Operational amplifier
IC3302
Active filter (acoustic characteristic correction)
IC3303
IC3305
VHILA4635A+-1S
Audio output amplifier
Power supply
IC3701
VHINJM2377M-1
DC/DC PWM control
circuit
T3701
RTRNZ0800CEZZ
DC/DC transformer
IC3702
VHINJM2147M-1
Operational amplifier, 31V/29V power supply stabilization
R3760
RVR-M8026TAZZ
B+ adjusting control (+5V adjustment)
Lamp error detection
Discrete circuit
Lamp error detection
AV2-IN/OUT
IC3501
VHITC4053BF1E
Audio I/O switching
Discrete circuit
Video I/O switching
TERMINAL UNIT
CIRCUIT
REF.No.
MAIN PARTS CODE
FUNCTION
AV1 input
Discrete circuit
Video/Audio/S video input terminal
Inverter circuit
T5701
RTRNZ0777CEZZ
LC-13B2H/M, LC-15B2H/M only
T5702
DC/AC inverter
Backlight lamp drive
JACK UNIT
CIRCUIT
REF.No.
MAIN PARTS CODE
FUNCTION
Operation circuit
Switches
Power switch, Channel selector UP/DOWN switch
Volume UP/DOWN switch, Menu switch, TV/VIDEO switch
OPERATION UNIT
CIRCUIT
REF.No.
MAIN PARTS CODE
FUNCTION
Remote control circuit
RMC4002 RRMCU0239CEZZ
Infrared remote control receiver
LED circuit
D4014
RH-PX0421CEZZ
Power LED (Standby: Red, Power-on: Green)
D4015
RH-PX0421CEZZ
Sleep Timer LED (Sleep Timer ON: Red)
R/C RECEIVER UNIT
CIRCUIT
REF.No.
MAIN PARTS CODE
FUNCTION
Inverter A
T6751
RTRNZ0798CEZZ
DC/AC inverter
T6752
Backlight lamp drive
T6753
Inverter B
T6551
RTRNZ0798CEZZ
DC/AC inverter
T6552
Backlight lamp drive
T6553
INVERTER-A/B UNIT (LC-20B2H/M only)
7
LC-13B2H/M
LC-15B2H/M
LC-20B2H/M
LC-15B2H/M
LC-20B2H/M
3-1. Tuner circuit
The tuner, whose RF circuit is composed of FET and whose local oscillation circuit, mixing circuit, IF amplifier
circuit and PLL circuit are composed of 1-chip IC, is 2-in-1 construction which has IF signal processing circuit
built in.
The channel selection circuit is of PLL frequency synthesizer type under the control of I2C bus. The receiving
frequency range is from 44.25 to 863.25 MHz, which can cover almost all VHF, UHF and CATV channels.
The IF signal processing circuit of the split carrier type employs the video PLL synchro system.
For video, a 1Vp-p composite signal is outputted from the terminal No. 19 (Video). For audio, a SIF signal is
outputted from the terminal No. 15 (SIF).
circuit and PLL circuit are composed of 1-chip IC, is 2-in-1 construction which has IF signal processing circuit
built in.
The channel selection circuit is of PLL frequency synthesizer type under the control of I2C bus. The receiving
frequency range is from 44.25 to 863.25 MHz, which can cover almost all VHF, UHF and CATV channels.
The IF signal processing circuit of the split carrier type employs the video PLL synchro system.
For video, a 1Vp-p composite signal is outputted from the terminal No. 19 (Video). For audio, a SIF signal is
outputted from the terminal No. 15 (SIF).
21
ANT
ANT
HPF
BPF RF AMP
BPF
RF AMP
T.BPF
MIX
OSC
LPF
SAW
VIF
AMP
VIDEO
DET
FM DET AF AMP
EQ
AMP
SAW
IF AMP
MIX
I
2
C PLL
OSC
MIX-PLL IC
T.BPF
VHF SECTION
AGC
1
AS
3
SCL
4
SDA
5
MB
6
BP
7
BT
9
IF OUT
11
SIF
AMP
AGC
AFT
18
MUTE
17
SIF
OUT 15
OUT 15
AUDIO
OUT 16
OUT 16
VIDEO
OUT 19
OUT 19
Fig. 3-1. Tuner circuit
VIDEO OUT signal waveform
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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