55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

[Sheldon]

Great forum, here's my problem and questions – I hope someone can help.
55” Samsung LCD LED TV, Model LE55A956D1M.

Bought December 2008 with 5 year warranty. No problems with it so I didn't renew the 5 years warranty insurance in December 2013. (Groan…).

In its 6th year it has started to exhibit a static grid of dark horizontal lines. The grid covers the full screen (top to bottom, left to right). However the grid is most prominent in the right hand side of the screen, gradually becoming less prominent towards the left hand side of the screen (the lines are still present but just less prominent – not as dark).

These dark horizontal lines are regularly spaced, with a separation between them of what appears to be 5 pixels. (the effect is a little bit like watching parts of the screen through a venetian blind…)

I've read about a Samsung LCD TV class action and recall due to using under rated capacitors in some of their TV's (e.g. 10 volt rated caps instead of 25 volt) – with the problem typically seeming to be that the TVs would go dead after 18 months and wouldn't switch on properly. To be honest it has been quite a shock to recently find out on the internet about the problems that have been caused by bad capacitors.

Anyway, I've opened the TV up and looked at the PSU board – the capacitors seem to be an assortment of 25V, 35V, 50V and 450V – with a temperature rating of 105 degrees C.

I think the label on them says ‘SamYoung' (or similar) – which sounds odd.

All but one of the caps appear to have a flat top and look ok. But one cap (25V, 1000uF) does have some slight doming/swelling on its top.

My questions are:

1. How likely is it that the problem of the horizontal lines might be being caused by that one capacitor in the PSU, with the slightest of doming on its top? Has anyone come across the problem that I have described above, as a result of bad caps in the PSU board? If the suspect cap is thought to be the problem should I replace just that cap or maybe instead also replace the other 4 caps that are close to it and of the same spec (25V, 1000uF)?

2. The capacitors seem to have been daubed/marked on the top with a black felt tip pen – is there any reason for this?

3. I can't seem to remove the ribbon cables that connect to the PSU board and I'm reluctant to try too hard in case I break them. Is it safe at all just to tug on the ribbon cables to wriggle the connectors apart – or is that definitely bad practice and that somehow I need to just grip the connector that is on the ribbon cable (and presumably squeeze in the side of the connector to somehow unlatch it whilst at the same time tugging the connector – for which there isn't much to get hold of and it does seem to be very difficult to do). Is a special tool required for separating the ribbon cable connector from the PCB?

Two pictures, one of the PSU PCB, and one of the TV's faulty screen display, are attached.

The picture of the PSU PCB does show the ribbon cable connectors that I am struggling with and also the suspect capacitor (it is the nearest one of the group of 3 caps in the centre of the photo).

All in (TV, 5 year warranty and wall mount) this 55” Samsung LCD LED TV cost near enough £2,900 in December 2008 and I would kind of like to keep it going without it costing much more than has been spent already…

Anyway, any help/advice gratefully received. Thanks.

Pete

[freakaftr8]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

definitely not a power supply problem so I wouldn't even worry about that aspect there's either something wrong with your T CON board in the top center that runs the panel or the panel itself has gone bad I know it sounds far-fetched but this does seem to happen frequently

[selldoor]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

55” Samsung LCD LED TV, Model LE55A956D1M.

My questions are:

1. How likely is it that the problem of the horizontal lines might be being caused by that one capacitor in the PSU, with the slightest of doming on its top? Has anyone come across the problem that I have described above, as a result of bad caps in the PSU board? If the suspect cap is thought to be the problem should I replace just that cap or maybe instead also replace the other 4 caps that are close to it and of the same spec (25V, 1000uF)?

I dont know much about big tvs or even small ones - perhaps Tom66 will look in and comment. As above I would not have thought that cap would
cause this. Perhaps pictures of the full board would help. If it affecting the voltage to the tcon then, who knows. If/when you get it fixed then yeas I would replace that cap and any with the same spec.

2. The capacitors seem to have been daubed/marked on the top with a black felt tip pen – is there any reason for this?

Often marked like that at the factory in some form of check.

3. I can't seem to remove the ribbon cables that connect to the PSU board and I'm reluctant to try too hard in case I break them. Is it safe at all just to tug on the ribbon cables to wriggle the connectors apart – or is that definitely bad practice and that somehow I need to just grip the connector that is on the ribbon cable (and presumably squeeze in the side of the connector to somehow unlatch it whilst at the same time tugging the connector – for which there isn't much to get hold of and it does seem to be very difficult to do). Is a special tool required for separating the ribbon cable connector from the PCB?

There are many different connectors - on the small poertion shown it looks like there is a bar along the side when that is pushed in it will release the catch at the bottom - you still have to pull and yes its just on the wires
so gently does it. Try and see how the clip works before you start pulling.

Sometimes there are push in clips on each end of the plug - again press and pull.
Sometimes there are no clips check for glue then if none just pull.
I sometimes use a watchmakers screwdriver and try and get it between the
plug and socket ans lever it up a bit- try not to lift one end too high bending the pins.



Tcon MAY look like this one http://assets.shopjimmy.com/media/ca...lj9402432e.jpg

[tom66]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

This is most likely a panel issue.
We had someone on here with the same issue, I'll try and dig the thread up. He tried everything, to no avail.

[Sheldon]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

Thank you everyone for your comments.

@tom66 - I think the thread you are referring to might be this one:

2008/9 Samsung LN55A950 Displaying Horizontal Lines:
https://www.badcaps.net/forum/showthread.php?t=31707

Had a quick look at the above thread late last night. I was a bit confused by other people chippping in with different problems together with all of the board swaps etc. - I do need to reread it again - but I don't think that it says anywhere that any of the capacitors on the PSU board were ever replaced - which I think is surprising (if true)?

My reasoning so far is this. The TV is a system comprised of a number of sub-systems (T-Con/Timing Control Board, Panel, External inputs, PSU board etc. etc. etc.). All of those sub-systems will have been initially designed and tested to behave in accordance with defined inputs that conform to a certain specification - and if any of those inputs are out of spec. then the performance/output of the sub-system will very likely be unwanted, undefined, random, unpredictable and unrepeatable.

So if the PSU board is in some way giving out 'dirty' power to certain sub-systems, maybe in the form of ripples due to capacitor failure then the knock-on effect on the rest of the system will be unwanted, undefined, random, unpredictable and unrepeatable !

So I'm thinking that the suspicious cap (and its mates) in the PSU board need to be replaced as the very 1st thing to do - and, as I said, it seems that this was never done in the above thread.

I can also see that it might be very tempting for Samsung technicians to, say, replace the panel and the T-Con board (value £100's?) and throw in to the customer "Oh by the way I also changed a couple of capacitors, worth a couple of quid, in the PSU board that looked a bit worn out". - Samsung gets to sell more expensive panels and T-Con boards, the technician makes more money by doing a bigger job, and attention is diverted from the (possible) fact that it was really just the inexpensive PSU board's caps that were to blame ! - But maybe I'm just a bit too cynical !

Also makes me think that maybe the TV subsystems should all incorporate some form of power conditioning on each board so that any dirty power due to PSU cap failure will be rectified/smoothed on the sub-system board - but maybe that might instead just introduce more capacitors/components and actually increase the probability of failure !

Anyway, I have ordered some Panasonic FC caps - these 1000uf caps have a low esr (30 mOhm for 35V, 38mOhm for 25V) and a claimed lifetime of 5000 hours. So I hope they will be ok.

Question - Presumably if I replace the existing caps with higher voltage caps (e.g. 35V for 25V) (and provided the size can be accommodated on the board) they will give the same electrical performance but be less stressed and hopefully last longer?

I think I just need now to build up the courage to have a go at doing the replacement(s). Gulp...

Thank you for you replies (esp. the advice on removing the ribbon cable plugs from the pcb).

Pete

[tom66]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

Pete,

I wish. On here, we have seen many LCD panels fail. That was the thread I was referring to.

Whilst it is plausible that a failing power supply could cause issues with the image, it will not typically present itself in this manner. LCD panels, whilst analog driven, are also very digital devices. Failing in such a repeatable manner typically indicates a failing panel source driver, or connection between source and gate drivers, both being unrepairable in most cases.

I suggested T-con in that thread because it seemed to be the most likely cause. However, what I've discovered now is that the vast majority of picture faults on Samsung LCDs are caused by panel failures, not T-cons. So I was obviously mistaken.

Using an oscilloscope you can see if the power supply rails are ok. You can see any such unstable ripple. Usually a DMM can pick up on a low rail voltage which can also cause issues. However, I would not expect a bad capacitor to cause this fault.

Good luck, let us know how it goes.

[truep]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

If you change the cap, and it doesn't fix it, at least you can sell the boards!

[freakaftr8]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

a lot of you're going to think I'm crazy but I had a TV come in it was a 55 inch LED and it had the same static horizontal lines on it the lines were black space perfectly evenly just like your panel and after much researching and the guy gave up and just said I could keep the TV I decided after extensive testing that I was just going to try something. I took a dremel tool and right at the very first line there was a good inch where there were no no no lines and then underneath there at the top the line started from there down. So basically looking at the whole screen the first inch from the top down was perfect then from that point down the screen was messed up. What I did was I took a Dremel and I ground the very side section where the line started down and the lines went away in the panel looks perfect to this day I gave it to a friend and they still use it. No I'm not saying do that to yours but this particular one is different when I apply heat to the section on the right hand side where the line started the lines went away under heat. And that's where I got the idea I have since done this to a few other panels and actually fixed them. I'm not sure if it's a manufacturing defect or some kind of particulate that got stuck in there under the manufacturing process that caused a short in the panel but I just thought I'd throw it out there. Again I know it sounds far-fetched but it did work for me three different times now one on a 55 on a 46 and one on a 32 inch all Samsung panels. Don't ask me why it works but it did. If you grind too much you'll stress a panel and crack it. just the very edge. One 55 inch I managed to crack this was the original one and I did and I stopped the bleeding in the screen with superglue on the side where I ground and it stopped from there but now there's a black spot on the top corner but it still works also.

everytime I see this defect it's usually related to something wrong on the right side of the panel not the left.

you could however start with the heat gun or a hair dryer approach on the top corners of the panel and see if the lines disappear

[mmartell]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

Interesting. You ground the edge of the panel where the first line was ? Must be a mechanical reason for this to work.

[Shinju]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

Photos of this dremel fix?

[Sheldon]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

Ok guys, here's an update.

I changed 9 capacitors on the psu board...

AND !!

..the problem remained, sadly. ;-(

But at least the TV didn't blow up and I don't think that I've made the problem any worse... (my glass is half full...)

Had a tentative warming with a hairdryer on the top right corner of the screen and couldn't see any kind of change so quit that approach before I did any actual harm.

Not sure about the dremel idea - I think I'd like to a see a few youtube videos showing exactly what to do before I would even think of exploring that option.

Anyway, all of my musings and hope that I'd built up about the problem possibly being caused by some caps on the psu came to nought.

Looks like I'll have to contact a proper service man and see if the problem can be sorted out.

To be honest I'm more inclined to pay out for a panel now - to get the most out of the super duper psu with its uprated caps !

Anyone know how much a replacement panel might be (in the uk) ?

Thanks.

Cheers,

Pete

[Sheldon]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

Just to close the story - I have recently contacted a Samsung authorised repair company who have told me that:

1. Because the lines appear on top of any selected TV menus that are displayed the company is 99% certain that it is the display panel at fault (rather than the display processor).
2. Replacement display panels for this TV are no longer manufactured or available from Samsung !
3. Because of the above (points 1,2) the repair company aren't interested in taking the TV in to give it a more thorough testing (thereby saving me paying them a £105 inspection fee to determine for sure that it is the panel – which they will then not be able to repair because replacement display panels aren't available).

This early generation 55” LCD TV has rear local dimming LEDs that make the chassis quite a bit thicker, heavier, and more unwieldy than many 55” flat panel LCDs that are available today. This depth also means that the chassis can accommodate decent sized speakers – and the sound is fine.

In some ways the problem is ‘not a majror problem' – the picture is reasonably watchable and although the picture is covered with these lines they are not currently too much of a distraction/irritant - and the problem doesn't seem to be getting any worse, although doubtless it will worsen in time. Nevertheless, I am concerned as to how the problem might develop over time.

The TV and original 5 year warranty cost something like £2800 in December 2008 and I'm really not happy that it seems that a major part (the display panel) appears to have worn out in less than 6 years (!) as a result of poor design and manufacture – and that it is not possible for me to get it repaired because replacement display panels are no longer manufactured or available.

I have laptops with screens that are still going fine after 10+ years so this development is really something that I hadn't foreseen.

Anyway, this is my very unsatisfactory situation with this Samsung TV – it seems I am now sentenced to watching an unsatisfactory picture for an undetermined period of time (10+ years ? !!!) until it gets so bad as to be unwatchable or it breaks down completely !

I can see now why some retailers offer a 5 year guarantee/warranty – but no longer, they know how long some of these display panels are likely to last.

It seems the key thing to look for is whether the display malfunction appears on top of any menus displayed by the TV - if the problem is there on top of the menus as well as the normal TV picture it points to it being a faulty display panel (rather than in the processing that determines the content to be sent to the display panel).

Anyway, hope that helps someone.

Pete

[mmartell]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

Horrible finish but thanks for the update.

[dkneyle]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

Mmmm...I'm working on a Chinese clone 46" with a Samsung panel. Pretty much same fault description. I'm about to transplant a swapped T-Con board but most pointers seem to suggest panel.

[tom66]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

It's unfortunate, that's for sure.

Thing is - at the time you bought your TV, display failures were very rare -- a few percent, at most, of total TV failures. Far more common failures were the repairable and replaceable bits - inverters, main boards, power boards, etc.

Now, it seems that the hard to repair or often impossible to repair parts are failing, one of the reasons I've stopped doing as many TVs as I was...

Things like the LCD panel... or the LED backlights... are failing more than the power board or main board.

[mmartell]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

Hey tom you as much or more than anybody around here understands the theory of construction and operation of lcd panels is there anything you can think of that would make these panels fail in the way that they do ?

[tom66]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

It seems to be down to heat. They've increased the density of the COFs and decreased the quantity so much now, but LCD panels use about the same amount of power (pixel drive ~15W for 40" panel; down from about 20W)

So that means the ICs can fail (i.e. shorted panel, seems to be common)

ICs on the flex are glued and soldered for electrical connection, if they get hot the solder balls underneath them can fail. I have had no luck attempting a reflow on the solder of a tab bond, may give it another go if I get desperate.

Interesting thing is, most LCDs got to around 1-2 tabs for the whole panel, even 1080p; plasmas couldn't get below about 12-15 drivers for the panel. I think this was one of the major cost deciders behind the death of plasma as everything else, even sus & power boards, should have remained cheaper.

[nomoresonys]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

"Anyway, this is my very unsatisfactory situation with this Samsung TV – it seems I am now sentenced to watching an unsatisfactory picture for an undetermined period of time (10+ years ? !!!) until it gets so bad as to be unwatchable or it breaks down completely !" these tvs were way overpriced when they came out, now tvs are much more affordable, trying to watch that tv, the way it is, would make me buggy, what I would do, is look for a tv that is repairable, but I would stay away from samsung, they seem to be the major brand with the most problems, according to the MANY MANY problem posts I read about, I would stay away from led tvs too, they seem to have many more problems than lcd and plasmas do.

[tom66]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

Samsung are by far the worst especially given the price premium they command, I have no idea why people still buy them.

[mmartell]

Re: 55” Samsung LCD LED TV Model LE55A956D1M with Static Horizontal Lines

It seems to be down to heat. They've increased the density of the COFs and decreased the quantity so much now, but LCD panels use about the same amount of power (pixel drive ~15W for 40" panel; down from about 20W)

So that means the ICs can fail (i.e. shorted panel, seems to be common)

ICs on the flex are glued and soldered for electrical connection, if they get hot the solder balls underneath them can fail. I have had no luck attempting a reflow on the solder of a tab bond, may give it a go if I get desperate.

Interesting thing is, most LCDs got to around 1-2 tabs for the whole panel, even 1080p; plasmas couldn't get below about 12-15 drivers for the panel. I think this was one of the major cost deciders behind the death of plasma as everything else, even sus & power boards, should have remained cheaper.

If I'm not mistaken there was at least one other guy who had the same problem where every fifth line was gone and many others who complained that every other line went dark. Would you be implying the cof's on the sides of the panel have gone or can a single cof failure anywhere cascade into a repeatable pattern such as this ?