i was having these same problems with the screen going black, and i found that when i hit the back of my tv it would work sometimes. so, i improvised on some of the advice on this page and so far no problems. here is what i did (its very easy):
1. lay the tv on the floor and take off the back panel. (i think 12 screws)
2. on the right side of the tv (as you are looking at the back) you will notice a large metal covering that is held in place by 6 screws. unscrew these and remove the metal cover.
3. you will notice that the three screw holes on the left side of the board have some sort of metal or solder around them, in sort of a star pattern. when i looked closely i noticed that most of the metal (solder) was tarnished, or kind of blackened. (this must mean that the ground screws werent getting a good connection and this would explain why it would work sometimes when i hit it because it would vibrate the screws enough to get a good connection! )
so, take a pencil eraser and erase all the black or tarnish off the metal surrounding the screw holes. thats it! (to be safe i took some sandpaper and cleaned up the screw holes on the back of the metal covering, but i dont know if that was necessary)
at this point i followed another gentleman's advice to do a hard reset. this involved unplugging the 8 connections although i dont know if this was really necessary because i believe my problem was a ground issue. i did it just to be safe. his advice is on this site if you want to do this step.
4. i put everything back together and it worked! i performed a soft reset at this point which puts your tv back to factory settings. just go to menu>setup>reset>return to factory settings? yes
this will turn your tv off and back on. that's it. so far so good for me.
Thanks to this forum, I was able to confidently contact Sharp and get my TV fixed.
My 32" LCD had the same problem (sound but no picture) and was out of warranty, however I phoned Sharp UK and suggested that it was a manufacturing defect rather than component failure and should be repaired free of charge - which they did!!
try accessing tv through the remote control.
I have a sharp aquos model lc-62c42u. when i power it on works great for about a minute. after that my screen has blue fuzzie lines with the picture still in the background. Ive already tried the INIT reset along with the K. is there any type of schematic I'm able to find on troubleshooting the power supply board.?
How many times does the POWER led flash per second? (Dont worry about the OPC).
1x (steady constant blink) = Lamps or inverters
2x = Power Supply
3x = Main Unit
If i am reading it correctly, looks like the POWER led is flashing 2x, which means it is a power supply failure. Either way, your TV needs to have a board replaced, there isn't anything you can do to fix it yourself. Try locating your local sharp authorized service center to repair your TV (1-800-237-4277)