Chosen Solution
Okay I’m back with ANOTHER broken Sharp Roku TV. Model # LC-50LB481U. It had all the signs of a bad backlight- fully functional and you could see the picture with a flashlight. I took the entire TV apart, found the bad LEDs and replaced the strips. After putting it all back together there is still no back light. It seems as if the correct voltage is not being supplied. I can light the LEDs by using my LED tester at the respective harness connector. I have tested the voltage at the LED harness connector and about 16 volts are being supplied where the LED tester would otherwise supply 59 to bring the LEDs on. I pulled voltages at the connector from the main board to the power supply (pics below): Top Row : 6.1V (fluctuating), 3.4V, GND, GND, 12.1V, 12.1V , 12.1V, 0 Bottom Row: 6.7V (fluctuating), 0V (no continuity), GND, GND, 12.1V, 12.1V , 12.1V, 0 As always, thanks for the help!
Back of Power board: A little blurry, I will take again and repost.
Update (07/26/2020) Better picture of back of power board :
Update (07/31/2020) Okay after replacement of the power supply board my TV is now operating normally. I am surprised that the TV required both LED strip AND Power Board replacement but it is what it is I suppose.
Hi @chillin014 , Are the voltage measurements for the connector pins as shown in the last image? So no +5V on either pins 15 or 16 - top row last pin on right, bottom row last pin on right? You have them both marked as 0. Not sure if the 6.1V fluctuating (pin 1 - top row first pin on left) means to turn off the backlights or to turn on the backlights. The pin is marked as DIM - which would make you think that it might be associated with the backlights. Mind you it may be the same with pin 2, the one marked On/Off Do you get audio as well as a display (without the backlights)? If so, it may be quicker to get a replacement power board - example only, than try to figure out what’s wrong with the power board without a schematic. Just a thought
Hi. I just remove the power supply board. I found out that the legend next to the connector and the underside legend are not the same. That was confusing to me. And maybe to others. The picture you show of the power board has the same problem with the wrong legend. I know why your voltages do not follow the legend next to the connector. I am not able to get the 5volts, only 0 volts comes up. The power to the back-lights is 63volts. I will replace the power board.
