sony kdl55ex720 (led error 4)

[gandhi55]

i have a sony kdl55ex720 that has backlight problem. The backlight usually comes on for a second or two but sometimes not at all. Flattening the bl_error line going to main power board clears the error (steady green stby light) but makes no difference to the backlight, it still goes out after a second or two. While the backlight is on its hard to tell for sure but i cant see any dark area's, i'm hoping its a board fault not the led's in the lcd panel. There is no change on pin 2 (fail) of the bd9276 on the LD board, cant find any info on the chip so i dont know what triggers the fail signal.
Does anyone have any info on this chip ?
Also i cant find a readable schematic for the G8 led power board ?
Lastly the led vcc from the G8 board is 203v while backlight is lit, then 181v when off. Is 203v too high ?
Any help would be greatly appreciated.

[budm]

Re: sony kdl55ex720 (led error 4)

Disconnect the LED connector and check the pin that you are reading the 203VDC again to see if it goes a lot higher than 203V, if it goes up just a little bit then more likely you have an open circuit in the LED strings.
Pictures of your backside of the TV that shows all the boards and the boards will help.

[gandhi55]

Re: sony kdl55ex720 (led error 4)

Thanks for the reply. I disconnected one of the led strips from the plug and the vcc went up to 260v (which worried me slightly the caps on vcc output are only 250v. I attached a picture of my set if it helps.