A common failure on the LG power supply is a high pulse capacitor location C822 value .022mF at 1.6KV. If you have a power supply that the capacitor C822 is black in color take a close look at it and note if it's bulged on the sides, if bulged must be replaced with an improved version, part is available at our web site. 
Models effected by this are the following 50PM4700-UB, 50PA6500-UA, 50PA6500-UG, 50PA5500-UA, 50PA4500-UF, 50PA4500-UM, 50PV400-UB 
Power supplies effected are the following: 
EAY62609701, EAX64276501