Chosen Solution
Samsung UN70NU6900FXZA I was only getting a flicker from the LED backlights. I have replaced the main board and the power board. It will flash the backlights. I had sound going after I checked the ribbon cables again. Then I turned it off and the the lights started flashing again and no sound. It’s not a strobe type flash it’s just on and off, they do dim down before going completely off. I disconnected one of the ribbon cables and the sound comes back on. So reconnected the ribbon cable and disconnected the other one and I still get sound but no picture. The backlights do operate normally with one of the ribbon cables disconnected. Do I have bad ribbon cables or is it something else?
Hi @bderby , What is the model number of the TV? Try the following: Disconnect the power from the TV and then remove the back cover and then disconnect the cable that goes between the mainboard and the power board, at the power board end. Reconnect the power to the TV The backlights should turn on and stay on. There will be no picture or sound because the mainboard has been disconnected. If they stay on measure the voltages on the connector on the power board where the mainboard cable was connected (before you disconnected it) to see if they’re as per what is printed on the board near the connector. If the voltages are all OK and the backlights stay on then most likely the problem is in the mainboard or the ribbon cable to the mainboard. Disconnect the power from the TV and then disconnect the cable between the mainboard and the power board and check the ends for corrosion and also test each wire for continuity. Be safety aware when testing the power board voltages, as there is exposed lethal AC voltage on the power board near to where you’re testing. If you don’t know how to test safely when AC voltage is present then don’t do it!
