i have the same problem, but my lg is fix now .
this problem is due of connection betuine lcd (the last point of left up )panal and lvds bord.
a little presson in this point the lvds signal will be ok .
1.u can open the bac of the lcd tv.
2.desassambl the front of the tv.
3. desassambl the front of the lcd panal .
4. the first group of wayer in the left must have more pression.
sorry i have a bad english
good luk