LG 42LF561V No Video after backlight repair

[zomi]

Re: LG 42LF561V No Video after backlight repair

Take a torch and shine around the edge of the lcd panel and check for any hairline cracks.

Do you have sound coming through ?

[london-freddie]

Re: LG 42LF561V No Video after backlight repair

No Scope in fact would not know where to start if I had one

[london-freddie]

Re: LG 42LF561V No Video after backlight repair

Can not see any screen damage and no sound

[budm]

Re: LG 42LF561V No Video after backlight repair

Are you sure you get 0V at the Vin test point? Vin test point should be connected to the output side of the fuse (right terminal of the Fuse).

[vinceroger69]

Re: LG 42LF561V No Video after backlight repair

budm a question, in fault finding no picture issues is it possible too test if lvds signal/voltage is going from the mainboard to the tcon if so can this be measured with a multi meter or will only a scope show the signal/voltage thanks.

[london-freddie]

Re: LG 42LF561V No Video after backlight repair

Sorry budm missed that testpoint but I can see it on my picture, can not check now as away from home till monday (working), but will check it as soon as I am back home.
Have got 13.3v at both ends of the fuse F1
I did notice big chip U11 seemed to be very very very hot when powered on, barely touchable
definately no voltages on any testpoints near the two ribbon connectors to panel
I have ordered a replacement tcon board (used) which should also arrive for monday

[budm]

Re: LG 42LF561V No Video after backlight repair

The LVDS will be very high and in mV range so DMM is not going to show anything much.

[vinceroger69]

Re: LG 42LF561V No Video after backlight repair

The LVDS will be very high and in mV range so DMM is not going to show anything much.

thanks budm will have a read

[budm]

Re: LG 42LF561V No Video after backlight repair

Sorry budm missed that testpoint but I can see it on my picture, can not check now as away from home till monday (working), but will check it as soon as I am back home.
Have got 13.3v at both ends of the fuse F1
I did notice big chip U11 seemed to be very very very hot when powered on, barely touchable
definately no voltages on any testpoints near the two ribbon connectors to panel
I have ordered a replacement tcon board (used) which should also arrive for monday

That may be a good way to try.
When you install a new T-CON, check the Voltages at those test points to see if they are present or not.

[london-freddie]

Re: LG 42LF561V No Video after backlight repair

Yes only a couple of pounds for the used tcon, so worth a try, will test voltages as soon as I fit it
Is it normal for that U11 chip to get so hot

[bman4]

Re: LG 42LF561V No Video after backlight repair

Usually When a chip is to hot to touch its shorted .Ive read that shorted leds can take out a t-con . i thought that is what happened when i tried subing leds and they blew but not in my case. Possibly static discharge ect.
I would say try with the pannel disconected but think its irellavent.

[london-freddie]

Re: LG 42LF561V No Video after backlight repair

OK Good news just got home from work and Mr Postman had delivered me a used tcon, just fitted it and picture has come back to life. So tcon had failed, maybe as bman4 stated the shorted leds had taken out the tcon, but tv did have a picture before I replaced the leds

[Dan81]

Re: LG 42LF561V No Video after backlight repair

I know it's a old thread but just wanted to share the same warning - if you have bad LED strips, take the connector out. The Heesung/AUO T-Cons are horribly sensible to bad LEDs.

As such, after replacing the T-Con, from a functioning TV sans backlight I have gone back to square one:

- new T-Con will NOT output any image regardless whether I take out one flex or another
- old T-Con also won't output image unless I take out the flex cable that goes to the left half of the screen

I suspect the old one might be salvageable, whereas the new one is as good as trash, likely. Would love some short insight from y'all before opening a thread. Same model btw, 42LF561V.