LG 42LG70 (CHASSIS:LA86D) Service Manual ▷ View online
- 29 -
Check the output (Pin AL25,AJ25,AK25) of
BCM355x(IC100).
Measure waveform at R2636,R2637,R2635 because
it’s more easy to check.
Can you see the normal signal? Refer to figure 1
Check the input (Pin 17,18,19) of NTP3000
((IC501). Can you see the normal waveform?
Refer to figure 1
Check the speaker output wafer P501.
Can you see the normal waveform?
Refer to figure 3
Check the connector & Speaker
Replace IC100
Speaker-Audio(Out)
YES
YES
YES
YES
Figure 1
Figure 2
Figure 3
NO
AL25 of IC100 / 17 of IC501
AK25 of IC100 / 19 of IC501
AJ25 of IC100 / 18 of IC501
Replace IC501
NO
Check the output
(Pin30,31,36,37,47,48,53,54)
of NTP3000((IC501).
Can you see the normal waveform? Refer to
figure 2
Replace IC501
NO
If P501 is damaged
replace P501
NO
- 30 -
Check the output (Pin AP11) of BCM355x(IC100).
Measure waveform at R2638 because it’s more easy
to check.
Can you see the normal signal? Refer to figure 1
Check the input of JK500, JK501.
Can you see the normal waveform?
JK500 : PIN1_ Refer to figure 2
/JK501:PIN3_ Refer to figure 3
After checking the Jack, you should decide to
replace item or not.
Replace IC100
Spdif & Coaxial-Audio(Out)
YES
YES
Figure 1
NO
If JK500 or JK 501
are damaged replace them.
NO
Figure 2
Figure 3
- 31 -
Check the output (Pin AN28, AP29) of BCM355x
(IC100).
Measure waveform at R685, R686 because it’s more
easy to check.
Can you see the normal signal? Refer to figure 1
Check the input of JK704.
Can you see the normal waveform?
Refer to figure 2
After checking the Jack, you should decide to
replace item or not.
Replace IC100
Monitor out-Audio(Out)
YES
YES
Figure 1
NO
If JK704 is damaged
replace it.
NO
Figure 2
- 32 -
BLOCK DIAGRAM
Fl
ash
(16MB)
DDR(3
2
MB)
(4x16x
4)
DDR(3
2
MB)
(4x16x
4)
74L
VC14APW
CS
5345
(Audio S/W
&A/D&)
MTV416
(Micom
)
NTP
3
0
0
0
(D-AMP)
X200
X-tal(54
)
PI
3HDMI
3
4
1
ATR
(3x1,S/W
)
EEPROM
A
T
/NT Tune
r
64Bit I/F
Reset
CVBS
CVBS/Y/C
Y/Cb/Cr
R/G/B
H/V Sy
nc
Audio L/R
I2S
MNT out
(L/R)
SPDIF
OUT
I2S
Dual LVDS
Conne
c
tor(4
0P)
Fu
ll H
D
(1080
P)
RS-232
C
Dead
IC
w
h
e
n
Sta
ndby
A
li
v
e IC
w
h
en
Sta
ndby
Video
Front
End
Dual
HDMI
Rx0
HD/SD
Video
Encode
r
Aud
io
DSP
BCM3552(HD)
BCM3553(FHD)
MCLK
MCLK
HDMI CEC
HDMI CEC(To
M
ico
m)
To Mic
o
m
SDA
SCL
SIF
IF(AT)
Buffer
Dig
ital out
IR & Local
KEY
Buffer
Buffer
24
C16
AGC CTL (F
ro
m
BCM)
USB
2.
0
I2
S Audio
In
put
VSB/
QAM/N
TSC/S
IF
AV
1
AV
2
COMP
1
COMP
2
CVBS
DDR(3
2
MB)
(4x16x
4)
DDR(3
2
MB)
(4x16x
4)
DDR(3
2
MB)
(4x16x
4)
DDR(3
2
MB)
(4x16x
4)
DDR(3
2
MB)
(4x16x
4)
DDR(3
2
MB)
(4x16x
4)
DDR (1
2
8
MB
)
RGB
Y/Cb/Cr
HDMI1
HDMI2
HDMI3
AV
1
AV
2
COMP
1
COMP
2
RGB
Co
axia
l
OUT (L
G
5
0)
USB
LG70: FHD-1
2
0
H
z
X400
X-tal(24
)
NVRAM
24
C512
EE
PROM
EE
PROM
EE
PROM
MT8280-
FG
DDR (6
4MB)
DDR(3
2
MB)
(4
x16x
4)
DDR(3
2
MB)
(4x16x
4)
DDR(3
2
MB)
(4
x16x
4)
DDR(3
2
MB)
(4x16x
4)
Dual LVDS
Conne
c
tor(2
6P)
X1000
X-ta
l(2
7
)
HDMI4
TMDS141H
AR
(1x1,
Equali
zer)
EE
PROM
Dual
HDMI
Rx1
HDMI CEC(To
M
ico
m)
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