Text preview for : 080a_tro.pdf part of LG 080a tro LG TV pt-48a80 080a_tro.pdf



Back to : 080a_tro.pdf | Home

Trouble Shooting

1. NO PICTURE ( SOUND OK )



CVBS Signal ?
Check MAIN1 Q026(E) Waveform. (2Vpp)




YES NO



NO
Check around
Waveform of AV Board Q200(E) ? Check Tuner(TU101)VIDEO output
IC200


YES


NO
Waveform of AV Board IC202 #11 ? Check around IC201, 202


YES


NO
Waveform of MAIN1 IC501 #63 ? Check AV Board VQ202(E)


YES


NO
Check around IC501 #37, #38, #39
Waveform of MAIN1 P503 #5, #7, #9 ?
Output circuit.


YES


Waveform of CPT Board NO Check around CPT Board
IC901R/G/B #3 ? Q901R/G/B


YES


NO
Waveform of CPT Socket Cathode
Check around IC901R,G,B
(RK/GK/BK) ?




- 17 -
2. NO SOUND (PICTURE OK)

< RF >


Waveform of AV Board IC7 01 Waveform of
NO NO Check
#47,48,50,51,53,54,56,57 Check JA202 Jack MAIN1 Q022(E)
at each Mode ? ( SIF ) ? TU101



YES YES


Waveform of Check
YES NO
AV Board IC701 around
#67 ? Q706




Waveform of AV Board NO
IC701 #27,#28,#25 ? Check around IC701




YES




Waveform of MAIN1 NO Check around AV Board
IC601 #7,#11 IC602 #7 ? Q703,704,705




YES




Waveform of MAIN1 NO Check around
IC601 #2,#4 IC602 #4 ? IC601,602




YES




Check AV Board JA501,
Main1 P602 Connector




- 18 -
3. NO PIP



Waveform of AV Board Waveform of MAIN1 Waveform of PIP
IC200 #27,29,31 ? Q027(E) ? Board IC1201 #28 ?


NO
Check JA202
YES YES


NO
Waveform of AV Board Check AV Board
IC200 #13 ? IC200, Q201
Check
YES NO ScartJack
JA204
YES



NO
Waveform of PIP Board Check PIP Board
IC1201 #26 ? Q1206




YES



Waveform of PIP Board NO
IC1201 #15~#18 ? Check around IC1201
(R,G,B, FB)




YES




Waveform of MAIN1 NO
Check PIP Board
IC501 #45~#48 ?
Q1203,1204,1205
( R,G,B FB )




- 19 -
4. NO Teletext(Picture OK)



Waveform of MAIN1
IC501 #59 ?

YES

NO Check PIP Board
Waveform of IC001 #12 ?
IC1205 #2, #4

YES

Check OPTION1 TEXT Code
(SVC MODE)




5. NO OSD (ON SCREEN DISPLAY)



Waveform of MAIN1 IC001#19,#20 ? Horizontal, Vertical Fly Back Input


NO


YES
Check DEF. Board.
Check MAIN1 Q010,Q009,Q002



NO
Waveform of MAIN1 IC001 #38,39,40,41 ? Check input power of IC001
(R,G,B,FB)

YES


NO
Waveform of MAIN1 IC501 #41,42,43,44 ?
(R,G,B,FB) Check around Q014, Q015, Q016, Q017




- 20 -
6. NO POWER ON

6.1 MICOM PART CHECK


Check input voltage of NO
Check SMPS Board
IC001#9,11,13,30,37,42,44


YES


Check IC001 #34,35 NO
Replace X001
(OSC)


YEs

NO
Check IC001 #3, 4 (SCL,SDA) Replace Q003, Q004



YES


LOW
Check IC001 #46 (ABN) CheckAbnormnal Circuit



HIGH


Check IC001 #24 ( IR ), NO
Check P004AP connector
#47~52 (Key In)




- 21 -
7. NO VFD OPERATION




Check AV Board IC750 #5 NO
Sound signal. Check IC701sound output




YES

NO
Check IC750 #3 output Check around IC750




YES

NO
Check IC001 #18, 21, 22 Check Q008, 007




YES


NO
Check IC001 #23, 25, 27 Check Q011, Q012




- 22 -
8.NO RASTER

Check +B voltage
at Pin1 of P805A.

Normal 0V



Is the voltage at Open
Check F801.
Pin 15,17 of IC501 3.3V? No

Check/Replace
Check 5V, 9V, F801, D802,
Yes OK
12V lines IC801,IC802.
Does the square
Check the voltage 0V
waveform from pin50
No of IC501 appear? of C812(+).
Yes

Check/Replace Check I2C Check/Replace
IC501 Yes D802.
Bus lines
(SDA, SCL)
Is the waveform at Check the voltage Lower than 6V
No collector of Q402 normal? at pin 4 of IC801.

Check/Replace Check/Replace
Q402, T401. Yes D805,Q801,
6~ 8V ZD801.
Is the waveform of collector
No of Q403 normal?
Check/Replace IC887, IC871.
Check the secondary voltage
Check/Replace
Yes are shorted
Q403.

Check/Replace
T401.




- 23 -
9.INCORRECT CONVERGENCE



Does the static convergence
correct?

Incorrect Dynamic Incorrect Static



Check the input voltage at Readjust static convergence
P201. by remote controller

Normal Abnormal Not controlled Controlled


Check pulse pin 125 Check voltage on the Are there pulse signal
O.K
of IC2051 (4MHz) SMPS PCB at pin 121 of IC2051

Y Abnormal Abnormal Normal


Check/Replace Check VBLK,HBLK at pin Are there VBLK, HBLK pulse Check/Repla
IC2051 2,4 of P404. at pin 3,4 of P404. ce Q2201

Y No Abnormal Normal


Check/Replace Check Check VBLK, HBLK
Check/Replace
IC2002 HBLK,VBLK on signal on the
IC2051
the DEF PCB DEF PCB




- 24 -