LG 19LN4050 (CHASSIS:LB35A) Service Manual ▷ View online
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Put into RF cable completely?
Abnormal screen (TV)
YES
NO
NO
insult RF cable tight and then
Cable nut screw tight.
1
Change Main PCBA
WAVEFORMS
Is 1.8V at 7pin of TU401?
2
Is I2C waveform
At 3,4pin of TU401?
3
4
Is IF waveform at 43
,44 pin of IC501?
NO
NO
3
3Pin of TU401 (SCL)
4Pin of TU401 (SDA)
4
43,44pin of IC501
If 1.7V is not at plus pin of TU401, check
It is over 3V at 2pin of IC401,
if it is not, Check Line between TU401
and IC401 is open or short.
Another is change IC401 or TU401
Check Line between TU401 and IC501
is open or short, Another is change
IC501 or TU401
Check Line between TU401 and IC501
is open or short, Another is change
IC501 or TU401
4. Abnormal screen (TV)-Main PCBA
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5. Abnormal screen (AV)-Main PCBA
Put into AV cable completely?
Abnormal screen (AV)
YES
NO
NO
Insult AV cable tight
1
Change IC501
WAVEFORMS
Is Input signal timing
and format in spec?
Change Timing to 480I, 576I
Or change format CVBS
2
Is waveform at R505
3
Check Line between JK101 and IC501
is open or short, Another is
change AV cable
NO
YES
YES
R505 (CVBS)
3
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6. No sound (all source )-Main PCBA
Does wire connect P301 with speaker?
NO sound (All source)
YES
NO
YES
NO
YES
Connect wire between P301 and speaker.
1
Change speaker and wire
Is 19.4V at 19,20,31,32pin
of IC301 ?
If 8V is not plus at L703, check
of JK700 is open.
If is not Check Line between L703
and IC301 is open or short.
.Another is change IC301
2
NO
Is 3.3V at 40pin of IC301?
If 3V is not plus 30pin of IC301,
check It is over 3V at L301
if it is not, Check Line between L301
and IC301 is open or short.
Another is change IC701,IC301
NO
3
4
YES
Is I2C waveform at
10,11pin of IC301?
Check Line between IC301 and IC501
is open or short, Another is change
IC301 or IC501.
NO
5
Is I2S waveform at
R301,R302,R303,R304?
6
Check Line between IC301 and IC501
is open or short, Another is change
IC301 or IC501.
YES
Is there any waveform P301?
Check Line between IC301 and P301
is open or short. And then check resistance
of speaker is under 4ohm.
Another is change IC301
NO
4
10pin of IC301
11pin of IC301
5
R301(SDO)
R302(WS)
R303(SCK)
5
R304(MCLK)
6
1pin of P301(Audio out)
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7. Abnormal sound (TV)-Main PCBA
Put into RF cable completely?
Abnormal sound (TV)
YES
NO
insult RF cable tight and then
Cable nut screw tight.
1
2
3
4
NO
Change Main PCBA
WAVEFORMS
Is 1.8V at 7pin of TU401?
Is I2C waveform
At 3,4pin of TU401?
Is IF waveform at 43
,44 pin of IC501?
NO
NO
3
3Pin of TU401 (SCL)
4Pin of TU401 (SDA)
4
43,44pin of IC501
If 1.7V is not at plus pin of TU401,
check It is over 3V at 2pin of IC401,
if it is not, Check Line between TU401
and IC401 is open or short.
Another is change IC401 or TU401
Check Line between TU401 and IC501
is open or short, Another is change
IC501 or TU401
Check Line between TU401 and IC501
is open or short, Another is change
IC501 or TU401
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