Sharp 80le632u lcd turn off randomly & suddenly

SOURCE: No picture, but power is on...

How many times does the POWER led blink per sec? (dont worry about the OPC)

2x = power supply (not as expensive to fix)
3x = Main board (expensive to fix)

SOURCE: No POWER

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)

SOURCE: Sharp Aquos turns itself off

How many times per second does the POWER led blink? (dont worry about the OPC).

1x per second (constant, steady blink) = bad inverter/lamps
2x per second = bad power supply
3x per second = bad main board

You can buy the parts online and fix if yourself!!

SOURCE: Sharp aquos lcd screen goes blank

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.

SOURCE: Sharp LC-26D43U Power light flashes and unit won't turn on?

It's a power supply related problem. When it turns itself off, this it called protection mode. The TV automatically turns off to protect other parts form being damaged.
The most common problem is the Power Supply Unit or the Backlight Inverter Board.
You may have to take the TV to a repair shop to find out which one is bad. Paying a repair shop to replace the board for you maybe more than the TV is worth. If you let them diagnose it and you replace the bad circuit board yourself, it would be cheaper.

Here's a place I use to get parts for TVs:
http://www.shopjimmy.com/catalogsearch/result/index/?q=LC-26D43U&p=1
The problem is the repair shop may charge you double or three times of what the part costs at the web site link above. Then, plus labor. I just want to save you money. :)