The screen was completely dark on a Samsung LN46C600. The power light worked normally, it made the normal sound when turned on, but just a black screen. With a flashlight you could see that the LCD was still showing an image.
Since ALL of the LED backlights were off it seemed pretty obvious that it had to be a power supply problem, rather than a bad LED (which might cause one LED string to go out).
It's pretty easy to take the back off the TV, removed the power supply board, and looked for failures. I didn't see it at first, but eventually noticed that CI818 was bulging. I found the power board schematic and some other documentation online (http://www.toms-service-manuals.com/), and it showed CI818 as 0.47uF at 450V. Digikey has the Panasonic ECW-FA2J474J (DK #ECW-FA2J474J) for just $0.81, which is 0.47uF at 630V. I replaced the bad part and the backlight worked again!
Since ALL of the LED backlights were off it seemed pretty obvious that it had to be a power supply problem, rather than a bad LED (which might cause one LED string to go out).
It's pretty easy to take the back off the TV, removed the power supply board, and looked for failures. I didn't see it at first, but eventually noticed that CI818 was bulging. I found the power board schematic and some other documentation online (http://www.toms-service-manuals.com/), and it showed CI818 as 0.47uF at 450V. Digikey has the Panasonic ECW-FA2J474J (DK #ECW-FA2J474J) for just $0.81, which is 0.47uF at 630V. I replaced the bad part and the backlight worked again!
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