Chosen Solution
40” Samsung LED Series 56 I’ve taken the back off now. When the control board is unplugged from the power l board the leds light up on the back of the TV. As soon as I plug the control board back into the power board all the leds go off. Does this mean the control board is defective?
@chuckcat that just means that your backlight is working. Your power supply supplies enough voltage to power the LED backlight. The issue now could be a bad main board (not telling the power board to turn the backlight on). I’d start with that. Also, check your main/power board if one the connectors on those boards says something like BL-EN and measure the voltage on that. You should get around 3.3V
