LG 37LC7D (CHASSIS:LB73A) Service Manual ▷ View online
- 17 -
Check J600 ,
Can you see the normal waveform?
YES
J600
may have problem. Replace this Jack.
After checking the Power of component switch,
you should decide to replace component switch
or not.
NO
Check the input of Component switch(IC707) ,
Can you see the normal waveform?
NO
YES
YES
YES
YES
After checking the Power of component switch
you should decide to replace component switch
or not.
Check the output of Component switch(IC707) ,
Can you see the normal waveform?
NO
After checking the Power of MST3361 you
should decide to replace MST3361 or not.
Check the input of MST3361(IC703 Pin41,44,46).
Can you see the normal waveform?
NO
After checking the Power of MST3361 you
should decide to replace MST3361 or not.
Check the output of MST3361(IC703 ).
Can you see the normal waveform?
NO
This board has big problem because Main
chip(HD2.4) have some troubles.
After checking thoroughly all path once again,
You should decide to replace HD2.4 or not.
Check the input and output of HD2.4(IC401).
Especially you should check
The H,V sync and clock.
Can you see the normal waveform?
NO
RGB_PC doesn’t display
- 18 -
Check input connect J700 , J701
Can you see the normal waveform?
YES
J700 , J701
may have problem. Replace this Jack.
After checking the Power of this chip, you should
decide to replace this or not.
NO
Check DDC communication lines(IC705 IC706
Pin5,6)
NO
YES
YES
YES
YES
After checking the Power of this chip, you should
decide to replace this or not.
Check HDCP communication lines(IC704 Pin5,6)
NO
After checking the trace of TMDS lines and
power of MST3361, you should decide to replace
MST3361 or not.
Check the input of MST3361(IC703)
This signal is TMDS.
Can you see the normal waveform?
NO
After checking the Power of MST3361 you
should decide to replace MST3361 or not.
Check the output of MST3361(IC703 ).
Can you see the normal waveform?
NO
This board has big problem because Main
chip(HD2.4) have some troubles.
After checking thoroughly all path once again,
You should decide to replace HD2.4 or not.
Check the input and output of HD2.4(IC401).
Especially you should check
The H,V sync and clock.
Can you see the normal waveform?
NO
HDMI doesn’t display
BLOCK DIAGRAM
- 19 -
HD2_DAC_LRCLK
HD2_ICE958_IN
HD2_DAC_SCLK
HY
5
7
V
1
61
61
0
SI
F
MS
P
4450
PA
L
T
une
r
(T
A
U
M
-W
1
0
1
P
)
CO
FDM
D
E
M
.+
DV
B
T
u
n
e
r
(T
DF
B-
Z205P
)
CV
B
S
Y,
C
IIC4
IIC1
99
Dat
a
[
0
:7
],
V
H
_
T
P
_
C
L
K
VA
L
ID
EE
P
R
O
M
(A
T
2
4
C
5
1
2
)
IIC2
SD
R
A
M
(
4
E
A
)
(H
Y
5
7
V
6
4
16
20
B
)
SD
R
A
M
(
4
E
A
)
(H
Y
5
7
V
6
4
16
20
B
)
Si
d
e
A
V
V,
L
R
3
Si
d
e
A
V
V,
L
R
33
Re
a
r A
V
V,
L
R
3
Re
a
r A
V
V,
L
R
33
Re
a
r S
YC
2
Re
a
r S
YC
22
MN
T_
O
u
t
V
1
V
11
MS
P
4
4
5
0
Ex
t A
L
R
22
TP/
D
1
99
YC
b
C
r
H,
V
,C
L
K
FI
D
30
YC
b
C
r
2020
H,
V
,C
L
K
33
Y/
U
/V
IIC3
Re
s
e
t
1010
TP
[
0
:7
],
TP
_
C
L
K
,
TP
_
v
a
li
d
CP
U
A
R
M
(S
3
C
4
4
B0
X
)
X-t
a
l
(1
0
M
)
I2
C
H
u
b
(P
C
A
9
5
16
)
IIC1
IIC2
IIC3
IIC4
IIC1
IIC2
IIC3
IIC4
IIC1
IIC2
IIC3
IIC4
KI
A
7
0
2
9
74
H
C
1
4D
Re
s
e
t
SD
R
A
M
(
2
EA
)
(H
Y
57V
6
4
16
20
B
)
SD
R
A
M
(
2
EA
)
(H
Y
57V
6
4
16
20
B
)
FLAS
H
(
2
E
A
)
(A
T
49B
V
1
60)
FLAS
H
(
2
E
A
)
(A
T
49B
V
1
60)
A/
V
S
W
(C
XA
2069Q
)
V1
SU
B
(V
/Y
O
U
T
2
)
VO
U
T
3
OU
T
1
Y1
/C
1
IN3
HD
-
2
.4
-T
P
D
e-
M
u
x
-M
P
E
G
D
e
c
o
d
in
g
:
MP
@H
L
-F
o
rm
a
t C
o
n
v
e
rt
e
r
-H
o
s
t I
/F
,
Me
m
o
ry
I/
F
-D
ig
it
al
I
/F
-Vi
d
e
o
D
A
C
,
N
T
S
C
En
c
o
d
e
r
-A
C
-3 D
e
c
o
de
r/
SPD
IF
In
/o
u
t
-I
E
P
2
SP
D
IF
Ou
t
SPD
IF
In
SPD
I
FO
ut
SD
R
A
M
I
/F
Te
x
t
De
c
o
d
e
r
(S
D
A
6
0
0
1
)
EP
L
D
1
(X
C
951
44
X
L
)
Co
n
tr
o
l G
P
IO
Pe
ri
p
h
e
ra
l
Bu
s
SP
ID
IF
_
IN_
B
Y
PASS
88
2
RX
[
0
:2
]–
,RX
C
–
DD
C(
I2
C)
EEP
R
O
M
(A
T
2
4
C
0
2
N
)
33
YC
b
C
r
Vi
d
e
o
S
W
(C
XA
2181Q
)
RG
B
-D
T
V
/-
P
C
5
RG
B
H
V
Co
m
p
_
1
YC
b
C
r
33
Co
m
p
_
2
YC
b
C
r
33
EP
L
D
1
(X
C
95144X
L
)
DV
I_
H
,V
,DE
FID
33
OR
3
IIC3
SI
F
PA
L
Tu
n
e
r
Ex
t A
L/
R
22
CX
A
2069
Co
m
p
_
1
22
L/
R
Co
m
p
_
2
22
L/
R
So
u
n
d
Pr
o
c
(M
SP
4450)
I2
S
O
u
t
33
HD
-I
I
HD
-I
I
I2
S
_
In
MN
T_
O
u
t
L/
R
22
RG
B
(P
h
o
n
e
)
22
L/
R
Au
d
io AD
C
(C
S
5331)
PW
M
MOD
U
LA
T
O
R
(N
SP
2100A
)
I2
S
PWM
A
M
P
(T
AS
5122)
PWM
A
M
P
(T
AS
5122)
)
OR
1
OR
2
OR
3
3
OR
4
VC
X
O
27
M
h
z
LG
D
P
L
L
(L
G
D
T
1
90
1B)
HD
2
_
V
D
P
C
lk
,
H
D
2_
N
T
2
C
L
K
RS
-232C
(S
T
3
232)
OR
4
HD
-I
I
DV
B
PAL
RF
SP
L
ITTER
HV
,D
E
RG
B
30
3
DO
u
tC
lk
LV
D
S
T
x
.
(T
H
C
6
3
L
V
D1
0
3
)
TX[
0
:4
]–
TX
C
–
12
LV
D
S
WA
F
E
R
E
EPR
O
M
(A
T
2
4C
02N
)
Bu
ff
er
(M
C
3
307
8)
CLK
11
OR
1
YC
b
C
r
3030
HD
M
I R
X
& A
D
C
(M
S
T
3
3
6
2
M
)
10
-b
it
HDM
I-S
te
reo
1A
+
1
D
Vi
d
e
o
A
/D
HY
5
7
V
1
61
61
0
EE
P
R
O
M
(C
A
T
2
4
W
C
)
uC
o
m
(M
T
V
4
1
6M
)
V4
Th
ro
u
g
h
ou
t
MAIN
(V
/Y
O
U
T
1
)
SPD
IF
R
x
.
(C
S
8
415)
RX_
H
D
M
I_
SP
D
IF
II
C
1
X_
ta
l
24
M
h
z
2
DDC(
I2
C
)
2
H/
V
X-t
a
l
(2
4
.5
7
6
M)
1
TX
T
_
C
V
B
S
2
IIC2
TX
T
R
/G
/B
,
FB
/H
/V
6
1
1
1
3
Pe
ri
p
h
e
ra
l
(F
MS
6403
)
33
YC
b
C
r
Y/
U
/V
3
H/
V
22
H,
V
,CL
K
OR
2
3
IIC4
FI
D
II
C
2
1
FI
D
OR
3
HD2_ICE958_OUT
1
IIC4
IIC2
II
C
2
2
HD2
_
S
Y
S
CL
K
1
EP
L
D
1
(X
C
9
5
288
X
L
)
2
HD2
_
S
Y
S
C
L
K
, E
P
LD
_
C
LK
IIC3
II
C
4
1
2
L/
R
SC
K
/
L
R
C
K
/
L
R
C
H
3
SC
K
/
L
R
C
K /
L
R
C
H
4
SC
K
/
L
R
C
K
/
LR
C
H
/
M
S
C
K
1
MC
L
K
2
B
SS8
3
Vi
d
e
o
Dec
o
d
e
r
(u
P
D
6
4
015
)
3D
Y
/C
S
e
p
a
ra
to
r
MEMO
- 20 -
Click on the first or last page to see other 37LC7D (CHASSIS:LB73A) service manuals if exist.