LG 42SL90-UA (CHASSIS:LA92S) Service Manual ▷ View online
VIDEO PATH
D-sub RGB
HDMI 1
Digital Audio (Optic)
RS-232C (Ctrl./SVC)
RGB/H/V
Half-NIM T
uner
MAX3232
Saturn6
Saturn6
(ATSC US)
(ATSC US)
LGE3369A
LGE3369A
MPEG2
Linux
Scaler
IF +/-
SIF
TU_CVBS
Reset / IF_AGC …
SDA/SCL_5V
HDMI4
Audio L/R
Audio L/R (for RGB)
HDMI 2
SPDIF
RX/TX
RX/TX
JACK PACK
JACK PACK
at REAR
at REAR
JACK PACK
JACK PACK
at SIDE
at SIDE
TR Buffer
VSB/QAM
Demod.
LGDT3305
TS In[0…7]
TS_clk, SOP, Val
EEPROM
AV
Component 1
Y Pb Pr, L/R
CVBS, Y/C, L/R
Component 2
Y Pb Pr, L/R
USB2.0
SCL, SDA_3.3V
DP/D
M
M
O.C. Protector
+5V
+5V
LCD Module
(FHD, 120Hz)
FRC IC
(LGE7329A)
DDR2(512)
Qimonda/Hynix
FRC Block
FRC Block
LVDS
HDMI 3
HDMI S/W
TDA9996
DDR2(512)
Qimonda/Hynix
SPI Flash
(2Mb)
X-tal
12MHz
X-tal
25MHz
A change of Brightness or OSD Flicker problem
Check OPC Status in the picture-Advanced Control
menu
menu
YES
YES
Video
This problem is side effect of OPC Function
1)A change of Brightness means Backlight dimming is operating by dark image
1)A change of Brightness means Backlight dimming is operating by dark image
because of OPC function
2)A phenomenon of flicker a specially bright area is Side effect because of OPC function
Recheck After OPC Off
YES
Ex1) A change of total brightness adding local bright image or
caption
caption
<
In excluding
a caption
>
<
In including
a caption
>
Ex2)
A phenomenon of moment flicker a specially
bright area after changing channel or input mode
CATV-3
CATV-3
<Before changing channel>
<After changing channel>
CATV-2
LA92S-Trouble shooting guide – Side effect of OPC Function
Check JK100 on main PCB, JK101 on sub PCB(side AV PCB)
Can you see the normal waveform?
Can you see the normal waveform?
NO
JK100(main PCB),JK101(Side AV PCB) may have problem. Replace this Jack.
Check the input (Pin U2,T1) of LGE3369(IC301).
Measure waveform at C614, C620 because it’s more easy to check.
Can you see the normal waveform?
Measure waveform at C614, C620 because it’s more easy to check.
Can you see the normal waveform?
LA92S Trouble shooting guide – AV
YES
Video
NO
This board has big problem because Main chip(LGE3369) have some troubles.
After checking thoroughly all path once again, You should decide to replace LGE3369 or n
After checking thoroughly all path once again, You should decide to replace LGE3369 or n
Check all power domain of LGE7329 (IC801)
(3.3V, 1.9V_CORE,1.26V)
(3.3V, 1.9V_CORE,1.26V)
& crystal output (X800 / 12MHz)&FRC_RESET
Measure Power & waveform at L800,L801,L802,L803,
L804,L806
because it’s more easy to check.
Can you see the normal waveform?
L804,L806
because it’s more easy to check.
Can you see the normal waveform?
YES
This board has big problem because FRC chip(LGE7329) have some troubles.
After checking thoroughly all path once again, You should decide to replace
LGE7329.
Although you replace it, you cannot see normal display, decide to replace
After checking thoroughly all path once again, You should decide to replace
LGE7329.
Although you replace it, you cannot see normal display, decide to replace
Main chip(LGE3369)
YES
Check JK101 or JK102 on main PCB
Can you see the normal waveform?
JK101 or JK102 on main PCB
may have problem. Replace this Jack.
Check the input (Pin R1,R3,P2 and Pin V1,V2,U1)
of LGE3369(IC601).
Measure waveform at C603,C604,C605 and C617,C618,C619
because it’s more easy to check.
Can you see the normal waveform?
of LGE3369(IC601).
Measure waveform at C603,C604,C605 and C617,C618,C619
because it’s more easy to check.
Can you see the normal waveform?
LA92S Trouble shooting guide – Component
YES
NO
Video
NO
YES
YES
Check all power domain of LGE7329 (IC801)
(3.3V, 1.9V_CORE,1.26V)
(3.3V, 1.9V_CORE,1.26V)
& crystal output (X800 / 12MHz)&FRC_RESET
Measure Power & waveform at L800,L801,L802,L803,
L804,L806
because it’s more easy to check.
Can you see the normal waveform?
L804,L806
because it’s more easy to check.
Can you see the normal waveform?
This board has big problem because FRC chip(LGE7329) have some troubles.
After checking thoroughly all path once again, You should decide to replace
LGE7329.
Although you replace it, you cannot see normal display, decide to replace
After checking thoroughly all path once again, You should decide to replace
LGE7329.
Although you replace it, you cannot see normal display, decide to replace
Main chip(LGE3369)
This board has big problem because Main chip(LGE3369) have some troubles.
After checking thoroughly all path once again, You should decide to replace LGE3369 or no
After checking thoroughly all path once again, You should decide to replace LGE3369 or no
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