Recently repaired a gray screen failure of a LeTV S50AIR C Luo LCD TV.
The user took it back from his daughter ’s house. The daughter ’s house was in the city.
The TV was broken. When the user and I came back diagonally to the door and asked me if I could repair it,
I said you had to get it back and I tried it. After all, I wasn’t completely sure. After about two months,
the user went to her daughter’s house to get the TV back. Put it in my shop and say that you repair it slowly.
If the screen is broken, you wo n’t repair it.
I say OK! After the user left, I put the TV on the repair station and started to remove the screws.
After all the removal, I started to plug in and found that there was a booting music screen.
The gray screen measured the voltage of the power supply and everything was normal.
It seems that the failure phenomenon is on the logic board.
It seems that the previous repairman has replaced the logic board,
and the logic board has been replaced a little bit, and the repairman tells
the user that the screen is broken and give up the repair! Pick up the multimeter
and start testing the voltage on the logic board (logic board model 6870C-0481A).
Only the input 12V voltage is normal, the insurance is intact, and all other voltages are 0V.
Troubleshoot the logic board because the previous repairer has replaced the logic board.
The problem must be the left and right side panels.
Start to disconnect the left side panel cable to start the test voltage is still 0V.
Shut down and disconnect the right side panel cable to start testing all voltages this time.
The normal voltage is VDD16V VGL-4.99V VGH28.24V HVDD8.06V The main chip voltage is 1.82V
All voltages return to normal. Shut down and restore the left panel cable.
On the left side of the boot screen, there are vertical lines on the logic board.
All voltages on the logic board are normal. It seems that the fault phenomenon is that
the voltage on the right board is plugged in. All voltages disappear and the right board is shorted.
The circuit voltage to ground resistance value found that the VDD16V voltage to ground resistance
was more than 300 ohms and a significant short circuit. Connected to the 12V5A switching power supply and started
to burn. It was found that the chip capacitor C182 was smoking. The measurement was indeed short-circuited.
Find a 0805 10UF chip capacitor. Replace the boot logic board. All voltages are normal.
Here I would like to share with you friends or masters who hope to encounter this failure, detour!
The clear picture is in the compressed package!
