Service Manuals, User Guides, Schematic Diagrams or docs for : LG TV cf29h30 MC74ATS
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TROUBLESHOOTING
NO PICTURE/
NO COLOR
Is the CVBS signal at pin6
of IC512 normal? No
Check IC512.
Yes
Is the CVBS signal at pin16
of IC201 normal? No
Yes Check/Replace IC201.
Are the CVBS signal at
pin13, 17 of IC512 normal? No
Check/Replace IC201,
Yes Q201.
Is the Y signal at pin28 of
IC512 normal? No
Yes Check/Replace IC512.
Are the R-Y, B-Y signal at pin29,
30, 31, 32 of IC512 normal? No
Check/Replace IC512,
Yes IC590, IC591.
Are the R,G,B signal at pin19,
20, 21 of IC512 normal? No
Yes Check/Replace IC512.
Are there R,G,B signal at
pin8, 9, 10 of IC511?
No
Yes Check/Replace IC511.
Check the IK signal at pin18
of IC512. No
Check the IK Line CPT
Yes Board.
Check CPT Board.
NO TELETEXT
Check the voltage 12V of
CT75.
Abnormal Normal
Check the 12V line to be Abnormal
Check the voltage of 5V line.
correct.
Check/Replace ICT75.
4.8~ 5.2V
No Check if video signal is input
at pin8 of ICT74.
No Check if video signal is Yes
input at pin16 of IC201.
Check I2C Bus lines.
Check/Replace Yes (SDA, SCL)
IC201.
Check the CVBS line.
OK
No Check the R,G,B signal at
pin15,16,17,19 of ICT74.
Check/Replace ICT74,
XT75. Yes
No Check the R,G,B signal at
pin9,11,13,16 of ICT76.
Check/Replace ICT76.
Yes
Check/Replace IC512.
NO PICTURE/NO SOUND
(RASTER OK)
Is the Auto search
operating?
Yes No
No Is the CVBS signal at Check the voltage NG
pin6 of IC512 normal? 5V,12V,33V SDA,SCL
of TUNER.
Check/Replace Check/Replace
IC512,T114 OK voltage, I2C Line.
Yes
GO TO OK Check pin15, 19 of
NO PICTURE Block IC12, IC20.
NO SOUND Block
NO RASTER
(SOUND OK)
Check the voltage of
CPT Heater
Normal Abnormal
Check the voltage of Check the Heater
HV,SCREEN of CPT pulse at pin 9 of T406
Abnormal Abnormal
Check the voltage of Check/Replace
200V Line of T406 Normal Normal T406
Check/Replace Check/Replace
CPT Board Connector, FR410,
FR901
NO SOUND
(PICTURE OK)
Check Sound system of
MENU OSD
5.5/6.0/6.5 4.5
Is the voltag of pin24 of Is the voltage of pin24 of
IC12 5V(High)? IC12 0V(Low)?
Yes Yes
Is the SIF signal of pin12 of
ICS17 normal? (Sound Board)
A/V STEREO MODEL No
Yes Check/Replace ICS17.
Check if the Audio signal at
Check if the Audio signal at
pin24,25 of ICS11 normal.
pin55 of IC512 normal. No
No
Check/Replace XS11,
Check/Replace pin1 of Yes
Yes ICS11, ICS12, IC201.
IC512, sound Board.
Check if the Audio signal
Check if the Audio signal
at pin2,5 of IC620 normal.
at pin9, 13 of ICS11 normal. No
No
Check/Replace Yes Check/Replace ICS11.
Yes ICS11,IC512,Q514,Q515.
Check the Audio signal at
Check if the Audio signal
pin7, 11 of IC620 normal.
at pin3,5 of IC620 normal. No
No
Check the voltage of
Check/Replace ICS11. Yes pin10, sound MUTE of
Yes
pin8 of IC620.
Check/Replace
Check if the Audio signal at
C664, C665, Speaker.
pin7,12 of IC620 normal.
No
Check the voltage of Normal
Yes pin10, sound MUTE of RF STEREO MODEL
pin8 of IC620. MUTE (A2/NICAM)
Check/Replace
C632, C633, Speaker.
NO RASTER
Check +B voltage at D825
CATHODE (130VDC)
Normal 0V
Is the voltage at Open
Check F801
pin12/37 of IC512 8V? No
Check the voltage
5V,12V,30V,40V Check/Replace
Yes OK
line F801
Does the square
waveform from pin40 Check the voltage 0V
of IC512 appear? of C808
No Yes
Check/Replace Check I2C Bus Check/Replace
IC512 Yes lines (SDA, D831~D834
SCL) 150~ 380V
Is the waveform of Check the voltage Lower than 6V
collector of Q401 normal? at pin 9 of IC801
No
Check/Replace Check/Replace
Q401,T451,R831 Yes R805,R806,D807,
6~ 8V Q800,ZD808,
D805,IC801
Is the waveform of
collector of Q402 normal?
No Check/Replace IC802,
D803, D806
Check/Replace Check if the secondary
Q402 Yes voltage are shorted
Check/Replace T406
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