That is a power supply issue and this requires a skilled person to do it.Trouble shooting in this kind of problem includes voltage measurement and resistance reading of the components/parts inside the high voltage section This is not a DIY problem but if you still want to do it yourself then I can give you some guide that you can try.
1.Check the power supply board,this board is where the power cord is connected.The common problem on this circuit are the filter capacitors .A leak and shorted capacitors always cause that kind of problem the worse is dead set.To visually identify a defective capacitor is their appearance they look to be bulging on top blown,theirs a liquid leak on the body.replace the defective capacitor if you found any.with the same rating and value..
2.Resistors -change value resistors and open resistance can cause the same problem this resistors usually near the regulator transistor.They appears as burned and overheated replace it with the same rating there is an available color code calculator of resistor in the internet click this link
and key in the color of the resistor to get the value..
3. check the voltage regulator transistor if it is shorted .the first pin and second pin must not have a reverse reading..
4.Check also the two big IC marked with STK xxxx this IC are the convergence IC it controls the horizontal pin of picture..when this IC are defective this will shut down the power supply ..
The steps I mentioned must be done with a skilled personnel If you feel you can do it,well you can try or better yet bring it to the service center or call a service technician...click this link
for service center
good luck hope this helps!