LG 32LV550T LCD TV strange vertical lines

[pelago]

Hi, first post here.

I have an LG 32LV550T LCD TV. It is showing a problem characterised by strangely coloured vertical lines on the screen. The lines are all over the entire screen, a few pixels apart. The lines are made up of multiple different colours, and the pixels in these lines change colours, even when the picture that should be displayed is static.

The problem occurs on all inputs, and in the built-in menus of the set, so isn't input-related.

I have reseated the two LVDS cables between the main board and the Tcon board, with no difference. Interestingly, if I completely disconnect one of the LVDS cables, the picture changes such that it is made up of thin vertical strips of the correct picture with black vertical strips in between. Where the black strips are not showing, the picture looks fine. If I plug that same LVDS cable back in, I think the strangely coloured vertical lines appear in the same spaces where the black vertical lines were.

I have tried jiggling the LVDS cables and that makes no difference. If I disconnect the other LVDS cable (whether or not the first one is plugged in), the picture completely disappears.

I haven't yet tried a different LVDS cable. Do you think it is likely to be a dodgy cable, or maybe a dodgy Tcon board? I'm hoping it isn't a dodgy panel.

I attach some pictures showing the problem, with the LVDS cable connected and disconnected. The "wide view" shots show that, when the LVDS cable is connected, there is some significant discolourisation or solarisation, but as far as I can tell, this only occurs in the strangely coloured vertical lines. The other shots are more zoomed in.

[ReeceyBurger123]

Re: LG 32LV550T LCD TV strange vertical lines

Thats a faulty colour chip on the tcon check what chip the tcon uses if its a as15 ?

[pelago]

Re: LG 32LV550T LCD TV strange vertical lines

Thanks for the reply. I'm not sure how to determine what the chip type is, but I attach some pictures of the Tcon board if that helps.

[pelago]

Re: LG 32LV550T LCD TV strange vertical lines

Reading up on it, I think the AS15 is a 48-pin chip, and the closest I see on that Tcon board is 40-pin.

I'm happy to replace the Tcon board if you think that is likely to be the problem, rather than the LVDS cable or panel.

The Tcon board is an LG Display Co., Ltd, MODEL: V6 32/42/47 FHD 120Hz, P/N: 6870C-0358A VER1.0, DESIGNED: 2010/10/25. Looking on flattvparts.co.uk I see that item available as a spare part for several different model TVs, none of which are my 32LV550T, at different prices. Would any of them work, do you think?

Looking closely at the 6870C-0358A Tcons to buy on that site, I see they have different text on the largest chip in the middle. My one says on it: LG Display, LG5820, 0ILEL-00369A, N4F127.00F 1115, which doesn't match any of the pictures of the other items. Do you think this text matters?

[Hamie]

Re: LG 32LV550T LCD TV strange vertical lines

Out of interest do the menus appear normal or are they also affected?

[pelago]

Re: LG 32LV550T LCD TV strange vertical lines

The menus are also affected (as mentioned in first post).

[pelago]

Re: LG 32LV550T LCD TV strange vertical lines

After viewing https://www.youtube.com/watch?v=J1GmfoeQeP4 which told me how to properly find LG Tcon board part numbers, I believe the part I require is a 6871L-2420B which is more specific than the generic 6870C-0358A part number. Haven't been able to find that replacement part yet though.

[budm]

Re: LG 32LV550T LCD TV strange vertical lines

I think the problem is on the main board video processor.

[pelago]

Re: LG 32LV550T LCD TV strange vertical lines

I think the problem is on the main board video processor.

Oh really? That's going to be more expensive than just replacing the Tcon. Can you explain your reasoning further?

[budm]

Re: LG 32LV550T LCD TV strange vertical lines

These two pictures are from posters in BC of what they found to fix the problem due to main board. I am making library of pictures to show if the problems are due to the main boards, the T-CON board, or the panel. So let me know what yours turns out to be.
You can try T-CON first.

[pelago]

Re: LG 32LV550T LCD TV strange vertical lines

I changed the T-CON, but am still seeing the exact same problem :-(

I haven't been able to find a replacement main board yet...

[pelago]

Re: LG 32LV550T LCD TV strange vertical lines

A local TV engineer I've shown this thread to (but who hasn't seen the TV itself) reckons this is likely to be a panel problem, and thus not economically fixable. I realise it's very hard to diagnose these things remotely, but what do others think? Is it still worth me trying to get a replacement main board? I don't want to waste money on that if it turns out to be the panel after all.

For more info, I think the strangely coloured columns are one pixel wide and exactly every four pixels (so a vertical strip of three pixels of correct colours in between each incorrect column). When I disconnect one of the LVDS cables, the black columns are two pixels wide, and still every four pixels. The black columns "remove" the strangely coloured columns, and so the picture looks almost OK, although obviously dark and half-missing.

[mattstolte]

Re: LG 32LV550T LCD TV strange vertical lines

These two pictures are from posters in BC of what they found to fix the problem due to main board. I am making library of pictures to show if the problems are due to the main boards, the T-CON board, or the panel. So let me know what yours turns out to be.
You can try T-CON first.

Budm so if menu is ok it is main board? Cause I got a 40 lg lcd that I picked up and the picture background is all green and menu is fine.

[pelago]

Re: LG 32LV550T LCD TV strange vertical lines

A local TV engineer I've shown this thread to (but who hasn't seen the TV itself) reckons this is likely to be a panel problem, and thus not economically fixable. I realise it's very hard to diagnose these things remotely, but what do others think? Is it still worth me trying to get a replacement main board? I don't want to waste money on that if it turns out to be the panel after all.

For more info, I think the strangely coloured columns are one pixel wide and exactly every four pixels (so a vertical strip of three pixels of correct colours in between each incorrect column). When I disconnect one of the LVDS cables, the black columns are two pixels wide, and still every four pixels. The black columns "remove" the strangely coloured columns, and so the picture looks almost OK, although obviously dark and half-missing.

I'm just wondering - is there any chance this could be a dodgy LVDS cable? (There are two between the main board and T-CON). I've tried prodding them with no change, but it would be much cheaper to replace those than to replace a main board or a panel. Could a dodgy LVDS cable cause the symptoms shown?

[pelago]

Re: LG 32LV550T LCD TV strange vertical lines

I've been reading up on baking boards in the oven. As I've probably not got much to lose, I might give it a go!

[pelago]

Re: LG 32LV550T LCD TV strange vertical lines

Well, I'm surprised, but baking the main board fixed it! I'm not sure how long the fix will last, but it's definitely not a panel problem, or a Tcon problem (I've changed back to the original Tcon and it still works). Thanks for people's advice here.