How to Repair LCD TV Backlight Shurdown Randomly
Model: Hisense TLM4777 LCD TV Chassis: GM1501 + FLI2300 Symptom: Tv Screen Came In with Tv Logo then No Display, Or Their Backlight Shutdown Randomly.
The customer brings in this TV and complaint that this TV screen will blank after the TV logo came out. But the sound is normal and you can control to change TV channel. This TV is using the Samsung LTA460WS-L03 LCD Panel. Where this LCD Module comes with the inverter board and the part number is: KLS-460BLWSA and B Rev0.1.
After using the PSU self test method and found that this LCD TV was the inverter board defective. This inverter was divided into two boards, one is A board (Master) and another one is B board (Slave). After checking most of the components in the both A & B boards, still can’t found any damage or leakage components. Because of this Tv backlight system just shutdown randomly only, so it is hard to troubleshoot it. After searching internet regarding this inverter board repairing information and found that it has a common fault about their ceramic caps. These ceramic caps will sensitive with the environment temperature or through their temperature changed their values will change too. So it will cause the protection system made a wrong decision to protect inverter board, even they are no any over voltage or over current occurs in the board or lamps.
The correct method to repair this inverter board is changing all these ceramic caps to 2200P ceramic caps. These caps are location at: C120, C180, C280, C380 & C480. Same as the picture below:
After changed all these ceramic caps and burnt in test about 7 hours, their backlight system still working good. Finally this LCD TV randomly shutdown backlight problem solved!
Notes: This KLS-460BLWSA Rev0.0 & Rev 0.1 inverter board has another common fault too. For example: 1) Symptom: The TV backlight blink once then backlight system shutdown. Cure: Replace their T320 & T412 (both part numbers are: BL009 593) HV transformer. Because of their ferrite core were cracked. 2) Symptom: No Display. Because the TV backlight not work. Cure: Check the Q101SMD transistor. Maybe it is burn or open.
Conclusion: The hardest symptom on repairing LCD TV is problem on “Randomly”! Because all the components are in ‘good’ condition, so we can’t measure the components with the multimeter or analogue meter only. Some we need some other extra repairing information to help us to troubleshooting the TV.
For more information on repair lcd tv, please click the button below to visit:
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To your success! Kent Liew http://www.LCD-Television-Repair.com http://www.Plasma-Television-Repair.com http://www.Projection-Tv-Repair.com
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