My Sharp LC-50LB261U tv screen went black but i still have sound. i replaced t-con board and power supply board and have same problem. can you help?

Best bet would be main board, sounds like firmware in EEProm is corrupt

The Ballast board that controls the backlight is next. Sounds like it has failed.

Hook the Tcon cable back up and do this. With a program running on the TV, shine a flashlight in the screen. If you can't see movement from the program, then the Tcon board is bad. you can get parts from here: TV Parts Universal TV Stands DLP Chips ShopJimmy

You will get a white screen when you unplug the t-con from the main board. Doing so removes power to the LCD panel. Verify that all of your voltages from the power supply are correct. If they are, I'd look at the t-con board. It sounds like there is a problem with the t-con that is pulling down the main board.

TV Parts Universal TV Stands DLP Chips ShopJimmy You can get the parts here and fix it your self. Look at the T con boards for your model.

WELL FOLKS I just FINALLY found what I have been searching for, I own a Sharp LC 32SH12U LCD TV that has begun to show problems with it's picture, Now it's sound is great no change..But it has gotten to the point that when i first turn it on all I get are three or four bright WHITE lines on the right side of the screen. They are a bout one third from the very corner of the screen.After it warms up for a while, MOST of the time it will just pop up and go to working just fine, that is what was giving it away to me that it HAD to be a something generally easy to fix, And in all of my searching I FINALLY found what I was looking for..Rite here on FixYA.com...There it was right thre in PLAIN ENGLISH..(( The T-CON BOARD )) Timing Control or LCD Controller..Board. on teh LCD panel Assembly, It transfers the image signal of the TTL and LVDS signal to specific TFT but What you all really NEED TO KNOW is JUST what is going on with your TV set when the T-CON Board is going bad, And I am about to tell you....So her ya go.. If you TV has any of these symptoms Well then I can pretty much say that your T-CON Board is bad or going bad...OK..If you have A Scrambled Picture,LINES,multiple Pictures Color smears, blotches, Rolling Pictures after warm up, Blown Surface mounted Fuse No Picture, Very Dark Screen almost like there is no backlight....Folks if your SHARP LCD TV is doing ANY of thsi then you just may need to replace your T-CON BOARD!!!! Hey it beats buying a new TV RIGHT!!!! GOOD LUCK FOLKS!!!!! I have already bought my replacement T-CON Board, as soon as I get it and install it I will let everyone know how it went!! PLEASE CROSS YOUR FINGER"S AND PRAY THAT THIS WORKS FOR US!!!! Thanks Wade in Eastman Georgia...

Don't feel bad. You didn't do anything wrong.
They sent you a TV with a bad power supply board for the
screen. The TV is trying to power up the screen, but it can't. Because of a defective part somewhere on the power inverter board for the screen. That is why the power/opc light is flashing.

I would call them back and and make them replace the TV.