Chosen Solution
Hi guys, I’m gonna try explaining my problem in detail and here i go: I have a 65” Samsung TV with back light issues, I checked the Strips and more than the half of the led where shorted, checked voltage from power board with everything disconnected and showed 320 V in both positive ends that feed the back lights, checked continuity in the wire lines that goes to the back lights and they’re OK. I read somewhere else that 320 V is OK when the back lights are disconnected, but I’m not sure. According the power board should show 220 V:
The power board is the BN44-00776A I ordered the parts, changed the back lights, and now when i do the back lights test i just see that they flash one time when i disconnect the power cord. Then i connected the rest of the TV without the Screen and just half of the back lights strips turns o, like in the picture:
Any suggestion about my problem would be fully appreciate!
Hi, What happens if you disconnect the mainboard from the power board and then connect power to the TV and turn it on, do the backlights come on and stay on or blink once or not come on at all? With the LEDs disconnected 320V is OK because that is the no load voltage. The power board is trying to drive the voltage up as high as it can trying to get the LEDs to turn on, i.e. get current to flow through the LEDs. That is as high as it can manage. If the LEDs blink once or don’t come on when testing as above, then it appears as though the power board cannot handle the load and is shutting down. This is sort of proven when you only connect half the backlights. They turn on i.e. less load on the power board. If half the original LEDs had faults, especially short circuits (and not open circuits) this most probably damaged the power board due to the excess current that would have flowed due to less resistance in the LED power circuit. This video may be of some help with the power board, as I cannot find a schematic for the board. You may have better luck. You did replace the faulty LEDs with ones that had the same specifications, didn’t you, just in case the replacements require more current etc. Just a thought.
