Sharp LC-20B4E (serv.man15) Service Manual ▷ View online
21
LC-20B4E
No sound (2/2)
Check all the settings microprocessor's adjust process menu.
Yes
No
No
No sound from SCART
No
SCART sound failure
Yes
No
Check IC1901 and its
peripheral parts.
Is output at pins (36) and (37) of
IC1901 normal?
Check IC1902 and its
peripheral parts.
Is output at pins (1) and (7) of
IC1902 normal?
Check their lines and their
peripheral parts.
Is input at pins (53) and (54) of
IC1901 normal?
Check IC1901 and its
peripheral parts.
Is output at pins (27) and (28) of
IC1901 normal?
22
LC-20B4E
8
7
10
9
6
5
4
3
2
1
A
B
C
D
E
F
G
H
CHASSIS LAYOUT
MAIN Unit
TUNER Unit
R/C, LED Unit
OPERATION Unit
23
LC-20B4E
17
16
19
18
15
14
13
12
11
10
INVERTER-A Unit
INVERTER-B Unit
24
LC-20B4E
8
7
10
9
6
5
4
3
2
1
A
B
C
D
E
F
G
H
BLOCK DIAGRAM
TUNER
I
2
C
MSP
SC3901
IC1901
SC_L/RO
TV_V
V1.SY
VP
I
2
C/UART
IC2010
S
SY
SC
MICON
IC2001
VIDEO
V1_V
L_
AUDIO
V1.L/R
(AV2) INPUT
REG
IC2003
J3701
DC13V
REG IC2004
INPUT
REG IC707
Q3707
PAVCC
Q3705
REG IC705
IC3702
Q3708
+32V
CONVERTER
IC702
Q3709
+8V
PWM IC3701
REG IC805
REG IC704
REG IC1607
B12V1A
Q3703
REG IC1602
REG IC1605
ANTENNA
SCART
(AV1)
AUDIO IN
AUDIO OUT
VIDEO OUT
SDA/RXD
SCL/TXD
VIDEO
IN
SC_R/G/B
SC5001
J5003
J5001
(AV2) INPUT
(AV2) INPUT
SIGVCC
INVVCC
REG IC706
+
3.3V
+3.3V
+1.8V
+5V
+9V
DC/DC
CONVERTER
T3701
+34V
+5V
+3.3V
+3.4V
+3.3V
−
11V
+23V
+17V
CHROMA
SELECTOR
IC803
AMP
IC808
TV/AV
SELECTOR
IC806
AMP
IC808
AUDIO MAP
IC1902
SIF1
AI_L/R
ANA_IN1+
SC2_IN_L/R
SC1_OUT_L/R
SC1_IN_L/R
CVBS/SY_IN
R/G/B_IN
SC_IN
REG IC703
VOLTAGE
DACM_L/R
I
2
C
I
2
C
DACA_L/R
A
SC2_OUT_L/
VPC
IC801
V2VO
SYNC SEP
IC802
E
2
PROM
CSYNC
I
2
C
UART
R
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