LG 19LN4050 (CHASSIS:LB35A) Service Manual ▷ View online
- 16 -
7. Abnormal sound (TV)-Main PCBA
Put into RF cable completely?
Abnormal sound (TV)
YES
NO
insult RF cable tight and then
Cable nut screw tight.
1
2
3
4
NO
Change Main PCBA
WAVEFORMS
Is 1.8V at 7pin of TU401?
Is I2C waveform
At 3,4pin of TU401?
Is IF waveform at 43
,44 pin of IC501?
NO
NO
3
3Pin of TU401 (SCL)
4Pin of TU401 (SDA)
4
43,44pin of IC501
If 1.7V is not at plus pin of TU401,
check It is over 3V at 2pin of IC401,
if it is not, Check Line between TU401
and IC401 is open or short.
Another is change IC401 or TU401
Check Line between TU401 and IC501
is open or short, Another is change
IC501 or TU401
Check Line between TU401 and IC501
is open or short, Another is change
IC501 or TU401
- 17 -
8. Abnormal sound (AV)-Main PCBA
wGGh}GG f
Abnormal sound (AV)
YES
NO
Insult AV cable tight
1
Change IC501
WAVEFORMS
pGG Gj\YWSj\YX
2
Check Line between JK101 and IC501
is open or short, Another is
change AV cable
NO
YES
j\YWSj\YXOG P
2
- 18 -
Ad
ap
to
r
S
ou
nd
A
M
P
N
TP
75
13
(
(
(
(
Mo
du
le
Au
di
o
O
ut
M
ST
68
41
XP
5
9
4
3
10
11
Tu
ne
r SD
A
Tu
ne
r SC
L
TU
N
E
R
IF
_A
G
C
B+
IR
/K
EY
40
24
M
hz
98
99
44
43
IC
5
0
2
Se
ria
l F
la
sh
8M
by
te
s
IC
5
0
3
EE
PR
O
M
24
C
64
30
LP
F
33
18
21
O
P-
A
M
P
x4
G
ai
n
Aud
io
L-O
ut
X
X
X
39
37
38
Aud
io
R-O
ut
H
D
M
I
SC
L/
SD
A
48
115
50
51
113
11
2
A
ud
io
_S
C
L
A
ud
io
_S
D
A
LV
D
S
O
ut
pu
t
P D
im
Inv
. O
N
P
_S
T
3.
5V
M
_3
.3
V
TU
_3
.3
V
19V
M
ai
n_
1.
2V
+1
8V
10
11
7
8
9
38
I2
S_
M
C
LK
I2
S_
W
S
I2
S_
SC
K
I2
S_
SD
O
10
8
11
1
11
7
IR
KEY
1
Led
_PW
R
10
2
105
53
52
45
85
84
EE
P
SD
A
EE
P
SC
L
94
95
97
96
SP
I_
C
LK
SP
I_
D
I
SP
I_
C
Z
SP
I_
D
O
S_
A
M
P_
19
V
32
40
LP
F
U
SB
_5
V
110
KEY
2
ST
_3
.5
V
P_
12
V
Q
71
0
M
ai
n_
1.
8V
M
_3
.3
V
Q
72
0
A
O
34
07
A
Pa
ne
l_
Vc
c
M
ai
n_
5V
To
U
SB
U
SB
_D
N
U
SB
_D
P
IF_
P
IF_
N
31
35
1.
8V
R
EG
7
TU
_1
.8
V
19
20
Aud
io
out
27,35,3
6
22,20,24,
77
62
54
41
30
18
9
116
10
7
10
0
101
Led
_PW
R
D
T1
64
1S
TP
S4
02
10
M
od
ul
e
B
LU
ĝ
ĝ
LE
D
_2
8V
B
LU
_2
4V
M
od
ul
e
B
LU
ĝ
M
P2
00
51
1.
8V
R
EG
M
P1
47
2
M
P1
58
4
M
P1
47
2
+1
8V
Q
71
2
To
O
P_
A
M
P
CVB
S In
AV
aud
io
in
BLOCK DIAGRAM
- 19 -
A2
A31
900
200
400
540
402
401
910
120
122
300
510
502
51
1
501
800
801
LV
1
EXPLODED VIEW
Many electrical and mechanical parts in this chassis have special safety-related characteristics. These
parts are identified by in the Schematic Diagram and EXPLODED VIEW.
It is essential that these special safety parts should be replaced with the same components as
recommended in this manual to prevent X-RADIATION, Shock, Fire, or other Hazards.
Do not modify the original design without permission of manufacturer.
IMPORTANT SAFETY NOTICE
Click on the first or last page to see other 19LN4050 (CHASSIS:LB35A) service manuals if exist.