LG TV video problem.

[Serge125]

Hi all!!

   Ok I just got this tv FREE from someone and he did told me of a video problem and even turned it on to show me and yes it does have a problem. He told me that it worked great the night before and next morning this problem. So can this be an easy fix or.... It's an LG 42LV5400-UB. So any thought or suggestions are welcomed!!

THANKS ALL!!

Serge

[Serge125]

Hi all!!

  Ok here's a video of what the screen does and please let me know if it can be fixed or not, up to now no one commented on this.

https://youtu.be/990e7Mn844c

https://youtu.be/W5ZYmxoIDHI

THANKS!!

[Rasz]

tcon or glass itself

[keymaster]

There is a big chance , the t-con board is the source of the problem .

[james_s]

That's what I'd suggest too, if you can find a t-con board for a reasonable price there's probably a 70% chance that replacing it will fix the problem.

[Serge125]

Ok what would be the 30% part? 😉 THANKS!!

[james_s]

Ok what would be the 30% part? 😉 THANKS!!

Driver ICs bonded into the glass panel itself, or possibly the main board that handles all the video processing and input switching.

[shakalnokturn]

Check LVDS interconnect between main and T-con all the same.
Also check power supply from main is clean when it reaches T-con.

I'd say T-con. is defective because the problem is affecting the whole picture (a defective panel will usually have localised defects), the dark trails on green background make it look like a LCD supply voltage on T-con board may be bad.

[Serge125]

I’ll check it tomorrow if I have time. There is a 12v on one of the pins but the repair manual doesn’t say so I hope that I’ll be marked on the board.

[Serge125]

Ok reopened the rear and this is a 52 pin (very narrow) and nothing is written on what pin does what and even though I do have the repair manual I don't see a 12v just a few 3.3v but how can I check that with the pins so close without touching the other pin close by. Here's where I got the manual if ever someone wants to "guide" me trough the pins.

https://elektrotanya.com/lg_42lv5400-ub_chassis_la12e.pdf/download.html

It's on page 34 for the LVDS pinout. Page 51 for the 12v but where on that 52 pin is it?? Ok maybe I just got it I'll check later on this. I think it's pin 51 with a few caps, hmmmm....

[james_s]

I would look for test points nearby, or electrolytic capacitors on the main and T-con boards, those are typically across power supply rails.

[Serge125]

I would look for test points nearby, or electrolytic capacitors on the main and T-con boards, those are typically across power supply rails.

Ok I think that I have tracked it down to the t-con 51 pin input from he main board. I have circled it in red and right beside it a fuse, so the 12v comes from main board goes to t-con passes through fuse then to the cap where I should get my 12v, right? And if I do get it then my t-con is the problem because the main is supplying the t-com with the needed 12v and if I get a different reading than the 12v then it's the main at fault.

[Serge125]

So am I right with what I said? Just don't want to just probe anything and short it. Oh yeah on the sham there is 3 caps and on the photo I just see one is it because there are other t-con models that has one of the 3 caps? THANKS!! ;-)

[Rasz]

yes, you can measure directly fuse on the tcon, not that I give tcon supply any significant chance of being the fault here

[Serge125]

yes, you can measure directly fuse on the tcon, not that I give tcon supply any significant chance of being the fault here

Yep checks out ok for voltage at the T-Con board 11.74v so will order a T-Con tomorrow and hope it will fix this!!

Thanks!!!

[Serge125]

Hi all!!!

   Ok I just installed a new t-con same problem!! So what can be causing this problem?? I'm getting the proper voltage to the t-con so it's something else but what any other suggestions?

Thanks!!!

[Rasz]

glass itself. Either inside the glass, glass-flex bonding or chip-on-flex TAB drivers

Russians are the only ones crazy enough to try and fix at this level without access to factory parts and TAB bonding machines.

https://web.archive.org/web/20161124102815/http://monitor.net.ru/forum/topic375748-0.html

TLDR: rip out LED backlight and power supply, those are handy for hobby projects. For example you could turn this dead TV into big light panel. Rest goes into recycle bin.