RCA RLDED 4331B: 43 inch LED TV: Backlight issue

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  • lmcancu
    Senior Member
    • Oct 2009
    • 158

    #1

    RCA RLDED 4331B: 43 inch LED TV: Backlight issue

    Hi I am having an issue with the LED backlight of this TV. I can see the picture with a flash light, so I determined it was a backlight issue.

    Initially, after opening it I found 2 shorted and 1 open LED on 2 strips (total of 4). I removed the LEDs and shorted the pads together to verify if the backlight would work.

    Testing it, I found the backlight turned on and I measured 54V when TV was in standby (off), and 100v when TV was turned on. The 4 strips each contain 9 LEDs, so 36 in all minus 3.

    Instead of putting it back together I decided to replace the LED strips so I bought 4 replacement strips. I tested them with an LED tester and they tested ok. However, when I installed the strips, 3 LEDs burned when I turned on the TV.

    I decided to replace the defective LEDs from my original strips with new LEDs that I purchased. The ones on the strips are 3030 3V 1W, and I purchased 3535 3V 1W. I replaced the 3 defective original LEDs, tested them with the LED tested and multimeter and they tested ok.

    I then installed them on the TV, and after turning it on, the LEDs just blinked once. I tested the strips again and found one of the old LEDs had shorted, so I replaced that one. After turning on the TV again, I only get one blink.

    Measuring the voltage, on standby its 54v, then jumps to about 90 when I turn it on, and goes back down to 62 V and stays there.

    Testing with the LED tester shows no issues, and it shows at 100V

    What's going on? The strips with 3 missing LEDs was working fine, but now that I have replaced them it no longer works?
  • lmcancu
    Senior Member
    • Oct 2009
    • 158

    #2
    Re: RCA RLDED 4331B: 43 inch LED TV: Backlight issue

    Found the issue I think. One of the new LEDs that I soldered wasn't properly connected to the positive pad. It would light when testing it on the strip with a multimeter but at 2.9 V instead of 2.5V. So I resoldered it properly and now the backlight is functional. I will leave it on a for an hour or two to see if other LEDs burn out or something

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