TV Repair Advice

Azok

Honorable
Apr 11, 2012
4
0
10,510
0
Hello,

I have owned my LG 47LS4600 for near 5 years now. I lightly use it and always run it in a power saver mode. Recently my children were watching it and the picture went out.

The TV gets power but the logo is not present upon start.
The menu cannot be seen with a flashlight.
The back lights light is working, but i have not inspected the strips.
Audio is still present.
No capacitors are bulging.
There is no visible damage to the components.

I do not own the hardware to test voltages, and I do not feel comfortable opening it more to inspect the back light strips if not necessary. I know these also contain fuses, but I cannot find anything besides a user manual, setup, etc. What should my next steps be as I have never done this? I would rather not spend $400 on a new TV.

 

InvalidError

Distinguished
Moderator
May 18, 2007
295
0
19,260
87
While bulging caps are a dead-giveaway, dead caps aren't always bulged. You could try unplugging the connectors for the board between the power and video processing board to see if a loose connection there may be getting in the way of the backlight control signal(s) and maybe re-seating the backlight power connectors in the top-right corner. If neither helps, then you really need to measure the backlight voltage on the power board to see whether the backlight power actually turns on. If there is no voltage there, it can be a control issue from the processing board or an issue on the power board, tough to call without going hands-on.

If the TV is anything like the LG monitor I repaired, the backlight brightness is controlled by a chip that uses I2C for communication. You'd need an oscilloscope to see if the chip is talking and rule out a control issue from the processing board.
 

Azok

Honorable
Apr 11, 2012
4
0
10,510
0
It’s edge lit and all the lights appear to be working. I had checked each connection. And replugged everything. I guess I have to buy a voltage tester and test each capacitor and diode?

 

Azok

Honorable
Apr 11, 2012
4
0
10,510
0
So I ended up replacing the Power Supply Board (with a working one) and it did not remedy the problem. Anyone know what I should do now?
 

ASK THE COMMUNITY