Samsung LE40A686M1FXXU Display Problem

[dick_barton]

Hello All,
I'm being offered a set that is in need of repair. It's a Samsung LE40A686M1FXXU

I don't have the set so cannot include photo's of the internal circuit boards; however I have included several pictures showing the lines on the screen that appear to follow any bright white object being displayed.

This can best be seen at https://youtu.be/ai4bOg0oIRI

Would I be correct in thinking either the LVDS cables have worked loose or the Tcon board needs to be replaced.

Any advice would be gratefully received.
Reagrds

[CapLeaker]

Re: Samsung LE40A686M1FXXU Display Problem

its more of a tab bond issue to me. do these lines clear up after leaving it on for a while?

[dick_barton]

Re: Samsung LE40A686M1FXXU Display Problem

Hello CapLeaker,
Thanks for your reply. There was no mention of them clearing up after time. However the video posted to me appears to indicate that they are not fixed to any position and tend to follow any bright white text as when displaying the On Screen menu.
Regards

[CapLeaker]

Re: Samsung LE40A686M1FXXU Display Problem

fiddle around with the tab bonds first.

[victor_cj]

Re: Samsung LE40A686M1FXXU Display Problem

You can try to make gamma calibration and adjustments of R/G/B/- offset from service menu.

[dick_barton]

Re: Samsung LE40A686M1FXXU Display Problem

Thanks for your resplies Capleaker & Victor_CJ
Regards

[dick_barton]

Re: Samsung LE40A686M1FXXU Display Problem

Hello All,
Further to my original request for advice on this set, I’ve now received it so I can supply pictures of the inner circuit boards.

The fan which should cool the IC under the heatsink was clogged with dust and also the IC too was smothered in a thick layer of dust. This has all been removed.
The set appears to work perfectly when connected to my Chromecast when displaying static images. Absolutely no sign of a tab/panel problem.

However, if I bring up the On Screen Menu I immediately have vertical lines from the top of the screen down to any bright white image being displayed.

When watching a TV program, these lines move left and right across the screen in line with any bright white image displayed.

I cannot get my head around why, if it was a tab/panel fault, a static image is perfect and when bringing up the On Screen Menu brings up this problem.

Once again I’d be interested in your thoughts.
Thanks in advance.


Victor_CJ & CapLeaker
Adjusting the Gamma made no difference when viewing the lines.
I’d like to leave stripping down to the tabs until I feel I have no further option.
Thanks to you both

.

[budm]

Re: Samsung LE40A686M1FXXU Display Problem

Does heating and cooling of the T-CON board has any effect?

[CapLeaker]

Re: Samsung LE40A686M1FXXU Display Problem

a bad tab bond can make the LCD "sluggish" to respond. So it would display a static picture, but if something moves... it take a half century to update. I see already vertical lines on your pics and does look like bad tab bond(s) to me. But don't rule the Tcon out yet.

[Diah]

Re: Samsung LE40A686M1FXXU Display Problem

I cannot get my head around why, if it was a tab/panel fault, a static image is perfect.

exchange the ribbon cable from T-CON to LCD, the 2 in the middle put them on the out side. an see the result.

[dick_barton]

Re: Samsung LE40A686M1FXXU Display Problem

Hello Budm,
I have a room fan cooling the Tcon board and all the IC's on it are cold to the touch so cooling doesn't seem to cure the problem. Perhaps as you say I should try heating it.
Thanks for you input.

Hello CapLeaker
I certain would agree with you but the On screen Menu also doesn't move and when displayed, immediately highlights the problem of the lines.
Thanks for your thoughts.

[dick_barton]

Re: Samsung LE40A686M1FXXU Display Problem

Hello Diah,
Out of curiosity can I ask what this may or may not achieve.
Regards

[Diah]

Re: Samsung LE40A686M1FXXU Display Problem

1- you will open them and put them back, mean this will clean,as you said it was fill with dust.

2- it may one ribbon had bad conection via the heat and dust.

3- any change of the result it help too

[dick_barton]

Re: Samsung LE40A686M1FXXU Display Problem

Hello Diah,
Thank you very much for your explanation which was very helpful. Unfortunately swapping the connectors as suggested has made no difference. Next job will be to clean them with alcohol.

Now that I have full access to the 16 screen tabs, I cannot find any one of them affecting the display when pressure is applied, either at the display bond end or the circuit board end.
Regards

[Diah]

Re: Samsung LE40A686M1FXXU Display Problem

then go heed to heat the T-CON as budum suggust

[dick_barton]

Re: Samsung LE40A686M1FXXU Display Problem

Hello Diah & Budm,

I have now completed the following two tasks:-

1. Cleaned the 4 ribbon connectors contacts on the TCon using isopropyl alcohol.
2. Heated up the Tcon board with hot air gun until components are almost too hot to touch

Unfortunately neither of the above has made any difference.

Regards

[Diah]

Re: Samsung LE40A686M1FXXU Display Problem

how about if you reset the TV to factory. did the first install page and the follow show you this issue?

[Moreno83]

Re: Samsung LE40A686M1FXXU Display Problem

I don't think it's a t-con problem but mainboard problem. Let the tv cool down and heat the mainboard ( big heatsink part ) and see if it changes. Tv must stay on!

There is a big gpu with small caps under that heatsink , due to heat over time the caps can fail.

[dick_barton]

Re: Samsung LE40A686M1FXXU Display Problem

Hello Moreno83,
Thanks for your input which is much appreciated and that will be my next job.
Thanks

Hello Diah,
A factory reset was one of the first tasks I undertook in addition to downloading the software from the Samsung website and flashing the TV.
Thanks

[Moreno83]

Re: Samsung LE40A686M1FXXU Display Problem

The lines follow the white/bright picture which looks like a video issue to me. Good luck!