Page 1
CONFIDENTIAL
LW29A13W/LW40A13W 5-1
5 Troubleshooting
Does proper DC 28 V appear at
DC jack connected to CN112?
Check SMPS PCB and Adapter.
Yes
No
Does proper DC 5 V appear
at Pin 1 of IC849 and Pin 2 of
IC828, IC830, IC852?
Check IC849, IC830 and IC828, IC852.
Check IC811 and IC817.
Yes
No
Does proper DC 2.5 V appear at
Pin 2 of IC804, IC806 and IC807?
Check IC804, IC806 and IC807
.
Yes
No
Does proper DC 3.3 V appear at
Pin 2 of IC800, IC801 and IC805?
Check IC800, IC801 and IC805.
Yes
No
Does proper DC 12 V appear at
Pin 2 of IC829?
Check IC829.
Yes
No
5-1 No Power
Page 2
CONFIDENTIAL
5 Troubleshooting
5-2 LW29A13W/LW40A13W
5-2 No Video (PC Analog Signal)
Power indicator is green
Does the signal appear at
Pin 7, 15 and 22 of IC203?
Check the R, G, B signal line and
related the R, G, B signal line.
Yes
No
Does the clock pulse appear at
Pin 30 and 31 of IC203?
Check IC203 and related circuit of IC203.
Yes
No
Does the colck pluse
appear at Pin 4, 10 of IC838?
Check related circuit of IC838.
Yes
No
Replace LCD Panel.
Page 3
CONFIDENTIAL
5 Troubleshooting
LW29A13W/LW40A13W 5-3
5-3 No Video (PC Digital Signal)
Power indicator is green
Does the signal appear at
Pin 80, 81, 85, 86, 90, 91,
93 and 94 of IC833?
Yes
No
Does the signal
appear at RA603, RA631,
RA632 and RA633?
Check IC833 and related circuit of IC833.
Check R2018, 2019, 2020, 2021,
2022, 2023, 2024 and 2025.
No
Yes
Replace LCD Panel.
5-4 No Picture (CVBS, S-VHS, Scart Video)
Check Pin 13, 15 (RF_CVBS1,
FR_CVBS2) of CN622?
Pin 9 (Scart1_Vin) of CN601
Pin 9 (Scart2_Vin) of CN621
Check Tuner, Scart1, Scart2 connector.
Yes
No
Check Pin 3 (YIN), 5 (CIN)
and 7 (VCR) of CN601?
Check RCA, S-VHS connector.
Yes
No
IC842 (VSP9437B)?
Check related circuit of IC842
and replace IC842.
Yes
No
IC308, IC309 and replace it.
Page 4
5 Troubleshooting
5-4 LW29A13W/LW40A13W
CONFIDENTIAL
Does the Low signal at
Pin 16 and of IC702?
Check Pin 1 and 6 of CN113.
Yes
No
Does the Low signal at
Pin 17 of IC702
Replace IC702.
Yes
No
Check Pin 67 (QSS_IF),
Pin 53, 54 (Scart1_In), Pin 50, 51
(Scart1_In), Pin 48, 47 (RCA),
of U458 (MSP3451)?
Check CN703.
Yes
No
Replace IC831 (MSP 3451).
5-5 No Sound (LW29A13W)
Page 5
5 Troubleshooting
LW29A13W/LW40A13W 5-5
CONFIDENTIAL
Does the Low signal at
Pin 16 and of IC13?
Check Pin 1 of CN624.
Yes
No
Does the Low signal at
Pin 17 of IC13
Replace IC13.
Yes
No
Yes
Does the Digital signal at
Pin 8, 9 and 10 of IC15?
Check IC18 and related IC18?
No
Check Pin 50, 52
(QSS_IF), Pin 44, 45 (RCA),
Pin 41, 42 (Scart1_In),
Pin 38, 39 (Scart1_In) of IC18?
Check CN629.
Yes
No
Check IC15 and realted IC15.
5-6 No Sound (LW40A13W)
Page 6
5 Troubleshooting
5-6 LW29A13W/LW40A13W
CONFIDENTIAL
5-7 LW40A13W (Digital Sound - coaxial optical)
Does the Low signal at
Pin 16 of IC13?
Check Pin 1 of CN624.
Yes
No
Does the Low signal at
Pin 17 of IC13?
Replace IC13.
Yes
No
Does the Digital signal at Pin 41
(coaxial), 43 (optical) IC15?
Check the CN627.
Yes
No
Yes
Does the Digital signal at
Pin 11, 12, 13 of IC15?
Check IC15 and related IC15.
No
Check IC14.
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