Service Manuals, User Guides, Schematic Diagrams or docs for : LG TV CF-21K57EX 078B_TRO
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NO RASTER
CHECK +B
at D821 cathode
Normal Abnormal
Check Open
Is the voltage at pin37
FUSE of AC line
& 12 of IC501 8V?
No
OK Check /replace
Yes Check the in/out Fuse,DB801
of IC841/IC844
Check pin40 Check the voltage
No of C805
of IC501(H-out) 0V
No
Check &replace
Yes 254~380V Check /replace
IC501
Check u-COM DB801
Check Q401 pin3 low?
Check the voltage
No collector waveform of pin3
Printed Circuit Board
Check &replace
Yes
Q401
Check T401
Check /replace
& each pin voltage
IC801,IC803,IC804
No
Check &replace Yes
T401
Check &replace
T401
NO TELETEXT
Check the
voltage at pin44 of IC01
0V 3V
Check& Replace
Check the waveform
IC01,IC03
at pin12 of IC01
NO YES
Check / Replace Check& Replace
Q512,R533 38~41pin of IC01
NO RASTER / SOUND OK
Check the
Heater voltage of CPT
(6 ~ 6.5Vrms)
OK Not OK
Check Check Check the
HV, Screen voltage of Ik Current of Heater pulse of FBT
CPT IC501, pin18 T701
Not OK OK Not OK OK Not OK
Check/Replace
Check Check
CPT Board
FR705,FR901,P302 FBT T701
Components
Check
Check
IC501, ZD901
FBT T701
P501, & P902
NO SOUND / PICTURE OK
MONO
Select correct system
in menu
OK
Check the waveform Check the waveform NO Check the waveform NO Check the waveform NO Check/Replace
NO
at pin 15 of IC501 at pin 2 of IC501 at pin 3 of IC201 at pin 1 of IC501 Z561,562,563,564
OK
OK
Check the waveform NO
Check/Replace Q601 Check the waveform NO Check/Replace
at pin 1 of IC601 IC201,Q205,Q206
at pin 9,10 of IC201
OK
Check the waveform NO
Check/Replace IC601
at pin 4 of IC601
OK
Check the voltage NO Check/Replace
at pin 5 of IC601 FR601,FR803,D804
RF STEREO
Select correct system
in menu
OK
Check the waveform NO Check the voltage NO Check/Replace
at pin 24,25 of IC101 at pin 3,13,14 of IC101 IC01,Q103,Z101,Z103,
Q108,Q109
OK
Check the waveform NO Check the voltage NO Check/Replace
at pin 24,25 of ICN03 at pin 16,33,45 of ICN03 ICN01,ICN03
OK
Check the waveform NO Check/Replace
at pin 4,12 of IC602 QN01,QN02
OK
Check the voltage NO Check/Replace
at pin 6,7 of IC602 Q602,603,IC603
OK
Check the waveform
at pin 1,2,14,15 of IC602
OK
Check the voltage NO Check/Replace
at pin 3,13 of IC602 FR601,803,D804
NO PICTURE / NO SONUD
Is any OSD displayed?
No
OK
OK Check IC01 pin38,39,40,41 Check receiving system in MENU
(R,G,B,FB) & excute Auto-program.
NO
Check IC01 pin19,20 Does the Auto-program OK
(V-Sync, H-Sync) operate properly.
Check IC01 pin34,35
(XTAL1,XTAL2) NO
& IC01
Store in manual-program MENU
Check NO Check 5V, 33V & IIC Bus Line
5V, 33V & of TUNER
IIC Bus Line
OK
Go to
NO Is the CVBS signal OK.
Check / Replace NO SOUND /
( IC501 pin6 )
TUNER, IC501 PICTURE OK
OK
Check NO
Check R,G,B signal
CVBS singal Line at IC501 pin19,20,21
& IC501
OK
Check / Replace
CPT Board component
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