Backlight problem on lcd tv

Hey guys

I got a small problem with an lcd tv, the thing worked fine, then stopped working and when it gets switched on the light flashes, so i open it up and found a blown transistor or what ever its called, its got 4 leg en small black square body just like a transistor, well anyway i got that fixed, but the backlights wont go on still, there is image on the display as i have connected the ccfl tubes from the tv to another inverter from ccfl pc lights and that works, but the tv inverter self isnt working,i get volts up to the input of the inverter transformer but no volts out to the ccfl tubes, is the inverter transformer probably blown adn how would i test it?

 

No backlight on lcd tv

Unfortunately the inverter circuit and power supply are on board, dont know where ill get a replacement board , i was thinking of using a lcd computer monitors inverter transformers if that might work?

 

lcd tv backlight problem

hey guys, so far no luck, got a inverter transformer from another lcd screen and same problem, now ive got a question, might it be the inverter driver mosfet?
The reason for asking is on the benq lcd pc screen ita has got 4 inverter tramsformers as well as 4 driver mosfets basically right behind the transformers, and well 2 of the backlights didnt go on but 2 did, found out it was the drivers mosfets on those 2, replaced them and all 4 backlight ccfl tubes lit up again....well except it still goes off after about 3 seconds,but thats another prject im working on,any help on that would be greatly appreciated.

So for the lcd tv which is the actual problem,how would i know if its the driver mosfet and where is the driver mosfet? I've attached 2 images, of what i think is the driver mosfet, i dont know.

But on the mosfet it states : " FML G22 " with the little diode symbol and 07 09.

Ive also read about a "pico fuse" but the board doesnt seem to have one on.

thanks so far for the help

 

lcd tv backlight

how do you mean th DC Rails?...ill see if i can post a pic bit later

 

i did check the volts going to the transformers, and i get about 24V dc going to the primary input of the transformers, but no volts going out

 

lcd tv backlight problem

attached is two pics of the bottom side of the power supply board, i made a circle around the component which i now suspect is the driver mosfet?.....the board had 2 and one was blown and caused the screen to power on and power off again in sequence, removed it and tv came on and got picture but no backlight

 

lcd tv backllight

both were exactly the same, uhm ill check the part number bit later, dont have it with me, but it did have two exactly the same ones on, and it looks to me like the power for the inverters come from them , or there abouts, i might be wrong, i followed the pcd tracks.

 

pcb not pcd sorry, oh and i dnt have a spare so didnt try replacing it yet

 

okay the "mosfets'' or regulators are the following stu 404d(7bd68) and the IC as far as i can make out, the writing is bit faded : u2003,xk 7n1

 

hey all i found this page as well http://www.scribd.com/doc/18180999/4/Different-part-list-for-models

 

on page 50 is the power circuit

 

i just checked the ic and from some of the pins that goes to the output of the inverter transformer(followed the schematic diagram in link above) theres either no volts or only about 2.7v........so most likely the IC?