Why my screen on my tv won't stay on and goes black

Fault to the main power supply regulator section. Either it will be a separate board, or the part of main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
http://electronicshelponline.blogspot.com/
It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.

did you hear the sounds? or maybe you have defective power source in hot side..

Hi Ricky, Power supply card seems to have gone bad in this case.If you are technical, try replacing power supply board or consult someone qualified to handle your set.

tried to connect again the supply for main board and disconnect the supply for the inverter board of back light. and turn on the tv, if the indicator stay the inventer board was the cause of voltage drop at the power supply board.

Hello,

Your power supply board is dead, u know basic electronics' and soldering? Most of the times, the power supply board just have dead leakages gases capacitors.These capacitors always bulges up on it top,or puff up on it top.Replaced these gases leakages capacitors will get your TV power stable,and work again.Or tries websites like Shopjimmy.com,Ebay.com to buy a whole refurbish power supply board for the replacement.

Take care in solving the problem....

You have a power supply problem. Within about 32 seconds the picture drops out because the backlite transformers shutdown. Yoy will have to find a new power supply or have some one fix yours.

There are two places to look for the problems, the backlight inverter board and the power supply. Look at the power supply first since it is easier to get to, look for burnt parts, bad capacitors, etc.
http://en.wikipedia.org/wiki/Capacitor_plague
Please post back what you find.

Hi, Replace the bulging capasitors on the main power supply board. Thanks.

It sounds like you have a power supply problem, this powers the inverter! Where you just replaced the inverter, we could assume it is good! Look for some bad caps (capacitors) on the power supply board. They will look bulged on the top an may be a little leaky (brownish stain). The power supply can fail on some output and be good on others. Was the back light inverter new? If all else fails, see if you can return the back light inverter and get another! I hope this is helpful!!