LG 42LB5DF (CHASSIS:LA75A) Service Manual ▷ View online
- 21 -
Ch
eck JP7
032, JP7033, JP70
34.
Can
y
o
u
see t
h
e n
o
rmal
w
a
v
e
fo
rm?
Ch
eck th
e C6
35, C636, C6
37 in
fro
n
t o
f
BCM35
53.
Can
y
o
u
see t
h
e n
o
rmal
w
a
v
e
fo
rm?
YE
S
NO
JK70
5 ma
y
h
a
v
e
p
ro
b
lem. R
e
p
lace th
is Jack.
NO
A
fte
r c
h
ec
k
the
pa
tte
rn be
tw
een
input
of
BCM35
53 an
d
JK705 ,
Yo
u
can
su
spect th
at PCB is bad
.
YE
S
Th
is
bo
ard
h
a
s b
ig
p
ro
b
lem
b
ecau
se Main
ch
ip(BCM3
553)
hav
e s
o
me
trouble
s
.
A
fte
r c
h
ec
k
ing thoro
ugh
ly
all pa
th
onc
e
ag
ai
n,
Yo
u
sh
ou
ld decid
e to
rep
lace BCM3
553 o
r n
o
t.
RGB_PC doesnt display
Ch
eck JP7
029,JP7030.
Can
y
o
u
see t
h
e n
o
rmal
w
a
v
e
fo
rm?
YE
S
NO
JK70
5 ma
y
h
a
v
e
p
ro
b
lem. R
e
p
lace th
is Jack.
YE
S
Ch
eck th
e R756, R759 in
fro
n
t o
f BCM35
53.
Can
y
o
u
see t
h
e n
o
rmal
w
a
v
e
fo
rm?
NO
A
fte
r c
h
ec
k
the
pa
tte
rn be
tw
een
input
of
BCM35
53 an
d
JK705 ,
Yo
u
can
su
spect th
at PCB is bad
.
- 22 -
HDMI doesnt display
Check input c
onnect JK602.
Can
y
o
u
see t
h
e n
o
rmal
w
a
v
e
fo
rm?
Ch
eck DD
C c
o
mmu
n
ication
lin
es
(IC601 Pin5,6)
Ch
eck th
e in
pu
t o
f PI3HDMI341
A
R
T(IC600)
Th
is
sign
al is
TMDS.
Can
y
o
u
see t
h
e n
o
rmal
w
a
v
e
fo
rm?
YE
S
YE
S
NO
JK60
2 ma
y
h
a
v
e
p
ro
b
lem. R
e
p
lace th
is Jack.
Ch
eck th
e o
u
tp
u
t o
f
PI3HDMI341
A
R
T(IC600 ).
Can
y
o
u
see t
h
e n
o
rmal
w
a
v
e
fo
rm?
YE
S
Ch
eck th
e in
pu
t an
d
o
u
tpu
t
o
f BCM3553.
Esp
ecially
y
o
u
sh
o
u
ld
ch
ec
k
The
H,V s
y
nc
and c
loc
k
.
Can
y
o
u
see t
h
e n
o
rmal
w
a
v
e
fo
rm?
YE
S
NO
NO
Af
te
r ch
ec
kin
g
th
e trace o
f
TMDS lin
es a
n
d
po
w
e
r o
f
PI3HDMI341
A
R
T, y
ou should decide to replace
PI3HDMI341
A
R
T or not
.
NO
YE
S
Th
is
bo
ard
h
a
s b
ig
p
ro
b
lem
b
ecau
se Main
ch
ip(BCM3
550)
hav
e s
o
me
trouble
s
.
A
fte
r c
h
ec
k
ing thoro
ugh
ly
all pa
th
onc
e
ag
ai
n,
Yo
u
sh
ou
ld decid
e to
rep
lace BCM3
550 o
r n
o
t.
Af
te
r
ch
ec
kin
g
th
e Po
w
e
r
of th
is ch
ip
, y
o
u
should decide
to replace this or not.
Af
te
r ch
ec
kin
g
th
e Po
w
e
r
of PI3HDMI341
A
R
T
y
ou should
decide to replace PI3HDMI341A
RT or
not.
YE
S
Ch
eck HD
CP co
mmu
n
ication
lin
es
(IC102 Pin5,6)
NO
A
fte
r
ch
ec
kin
g
th
e Po
w
e
r
of th
is ch
ip
, y
o
u
should decide
to replace this or not.
- 23 -
BLOCK DIAGRAM
LG Electronics. Inc. All right reserved.
- 24 -
EXPLODED VIEW
120
121
510
500
700
300
200
802
520
910
900
804
530
600
610
810
820
400
800
803
805
806
801
807
200T
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
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