Samsung LE40A656A1F - Possible T-con fault?

[tom66]

Re: Samsung LE40A656A1F - Possible T-con fault?

Sounds like a panel failure to me. Certain Samsung TVs of this generation are very prone to it. Do you have a picture of the fault?

[im_at_a_loss]

Re: Samsung LE40A656A1F - Possible T-con fault?

Hi Sorry to hijack your thread, new to the site and wasnt sure where to go. i Have the same problem with a friends samsung same model by the looks of it. I have changed the t-con board and the t-con cable which has resolved the issue it came to me with. My friends now tells me that the problem it now has ( Red vertical lines and some other colours now and then ) is the original problem until it stopped showing any picture at all other than the lines.

I was wondering if that the problem was originally with the main board and because he kept using it, he then has blown the t-con board and cable ( tested all and the original board and cable show no picture new board and cable show picture bit with lines ).

Just after your thoughts before i tell him we need a new main board.

Many thanks.

[senndogg]

Re: Samsung LE40A656A1F - Possible T-con fault?

OFF topic: i watched many reviews on youtube but was still not convinced either for a second hand Fluke or for a new from any other (Amprobe, Vichy, Unitrend etc). since shipping was a bit costy from the US, i followed mariushm advice. he had written a detailed review of his UT61E. i had this in my hands for 60$.

as for the Sammy, the owner collected it from my store from second time. he is desperate as no other technician in the area has not gone so far in troubleshooting. he confessed me last time. if he ever decides to throw it, i will make him a small offer.

[retiredcaps]

Re: Samsung LE40A656A1F - Possible T-con fault?

One retiredcaps bonus point for a picture of your multimeter.

I see the Uni-T UT61E is quite popular in outside North America.

[senndogg]

Re: Samsung LE40A656A1F - Possible T-con fault?

your only contact with the LCD panel are tab bonds. you can press them and see if the picture gets better. to do that, you should take the display and the entire structure out of the front bezel. than put it in a huge table backside down. you have to do 10-15 screws to remove the thin metallic front structure which secures the lcd panel. now you have access to them.

in my case, i desperately stripped it again. nothing doubtful. searched for a failed cap, everything ok. now im thinking where to throw it.

[prols]

Re: Samsung LE40A656A1F - Possible T-con fault?

Thanks senndogg.
Played with the T-Con board, seems fine to me.
I am trying to establish where the problem lies, inside the LCD panel or outside.
The fault affects the whole panel...?
Can LCD panel be opened and fixed?

[tom66]

Re: Samsung LE40A656A1F - Possible T-con fault?

sorry, i was not very clear. its in an another thread, a LE37S86BD i repaired 2 weeks ago, had a bad ribbon which caused a slow refresh rate, that was a Chungwa HD ready panel and had completely a different design.
Yes, the LE40A656A1F uses a Samsung Full HD panel.

Crappy Chungwha panels... Hate 'em with a passion. Have one now with hideous mura...

[senndogg]

Re: Samsung LE40A656A1F - Possible T-con fault?

sorry, i was not very clear. its in an another thread, a LE37S86BD i repaired 2 weeks ago, had a bad ribbon which caused a slow refresh rate, that was a Chungwa HD ready panel and had completely a different design.
Yes, the LE40A656A1F uses a Samsung Full HD panel.

[tom66]

Re: Samsung LE40A656A1F - Possible T-con fault?

the slow refresh rate in my case was in a Samsung but Chungwa panel. it was fixed, but the issue on this 40" Samsung seems permanent.

I thought this TV used a Sammy panel?

[senndogg]

Re: Samsung LE40A656A1F - Possible T-con fault?

the slow refresh rate in my case was in a Samsung but Chungwa panel. it was fixed, but the issue on this 40" Samsung seems permanent.

[tom66]

Re: Samsung LE40A656A1F - Possible T-con fault?

Shame about the bad panel issue. Seems all too common with Samsung LCD panels.

[senndogg]

Re: Samsung LE40A656A1F - Possible T-con fault?

mine began "clouding" again. now i have an official faulty LCD panel. now it is similar to the one in the video.
@prols: the slow refresh rate might be because a bad tab bond. if you can strip it you can try pressing them and see if there is any difference.

[prols]

Re: Samsung LE40A656A1F - Possible T-con fault?

Hi everyone. I'm new to this forum.
I have a Samsung LE40A656A1F to fix with some weird clouding effect.
Searching on the web led me to the following video:

http://www.youtube.com/watch?v=rcGSStFgjeA

Look at top left screen @ 1'25" to 1'35" and spot the time it takes for the white line to disappear, very slow reacting LCD screen.

This suggest that the problem could be a common one.
Caps on the PSU board are fine, so are the voltages and the ripples.
T-Con pcb and ribbon cables seem ok.
Does anyone have experience with this problem?

[senndogg]

Re: Samsung LE40A656A1F - Possible T-con fault?

its the second case in one month, that a Samsung panel suffers a bad ribbon/flex. the strange thing is that i played with the ribbons a lot before swapping the t-con. only after removing one ribbon it started working.
anyway, this fix will somehow extend the life of this full HD panel. lets hope.

[tom66]

Re: Samsung LE40A656A1F - Possible T-con fault?

well, thats getting weird.
12V is steady.
removing ribbon 1 (from the right to the left) showed bright colored vertical lines all over the screen.
removing ribbons 3 and 4 caused: the half screen (attached to ribbons 1 and 2) worked ok.

re-inserted all 4 ribbons and the tv was working properly. switched to the old t-con and it is still working ok. by the moment i have switched on/off 10 or more times and it is still ok. i bet the panel is coming near the end.

You probably have a failing flex on the panel, but you're getting somewhere... maybe you can fix it by providing some rigid support? Those ribbons on mine looked really bad.

[senndogg]

Re: Samsung LE40A656A1F - Possible T-con fault?

well, thats getting weird.
12V is steady.
removing ribbon 1 (from the right to the left) showed bright colored vertical lines all over the screen.
removing ribbons 3 and 4 caused: the half screen (attached to ribbons 1 and 2) worked ok.

re-inserted all 4 ribbons and the tv was working properly. switched to the old t-con and it is still working ok. by the moment i have switched on/off 10 or more times and it is still ok. i bet the panel is coming near the end.

[tom66]

Re: Samsung LE40A656A1F - Possible T-con fault?

Also, try with just some of the LCD ribbons plugged in. If it works, then it could be a shorted driver flex, which would be a difficult thing to fix...

[tom66]

Re: Samsung LE40A656A1F - Possible T-con fault?

My guess would be either main board, or sadly the panel itself :\. Is the T-con getting 12V (or 5V - forget which?) If you have a scope check ripple and stability. That T-con worked otherwise apart from faint lines on the screen.

[senndogg]

Re: Samsung LE40A656A1F - Possible T-con fault?

hello again!

the new t-con supplied by tom did not solve the problem. it still persist. any possibility it might be the lvds cable, or i should surrender?

[senndogg]

Re: Samsung LE40A656A1F - Possible T-con fault?

i really appreciate it tom!
i am gonna let you know after testing the ldos by tomorrow! thank you very much!