# How to fix LCD TV flickering



## TH3_H4NGMAN

My Sony KDL-46W4100 is flickering, as seen in this video:






As you can see, the left side flickers and the center has a dark column, although the right side is fine. Any ideas on how to fix this? Thanks for any help.


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## Nick2253

Does it do this will all inputs?


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## animal0307

Wonder if something died in it. If you crack it open I'd look for blown caps and in general blown/burnt bits inside.

Check this out for a walk through on blown caps and how to fix them. Clicky for the Sticky


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## TH3_H4NGMAN

Quote:


> Originally Posted by *Nick2253*
> 
> Does it do this will all inputs?


Yeah. I tried it with VGA and Component and still flickers.
Quote:


> Originally Posted by *animal0307*
> 
> Wonder if something died in it. If you crack it open I'd look for blown caps and in general blown/burnt bits inside.
> 
> Check this out for a walk through on blown caps and how to fix them. Clicky for the Sticky


I'll crack open the back and take a look. Thanks for the link. I'll report back with my findings.


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## TH3_H4NGMAN

I took off the back and saw this


I'm not sure if I need to take off that silver metal to get to the caps or what. From what I could tell, this is the only thing I could see that looked like a bad cap


Thoughts?


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## Nick2253

For future reference, here is the service manual for your TV. It doesn't have your answer, but I thought you might like to have it:

http://www.electronica-pt.com/index.php/component/option,com_remository/Itemid,34/func,startdown/id,8438/

EDIT: As far as your situation is concerned, I think you have a leaking capacitor on your hands. At the very least, it's really cheap to replace a film capacitor (which is what that is. Either Capacitor C6552 or C6550 in the service manual, I can't tell which one is leaking).


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## TH3_H4NGMAN

Quote:


> Originally Posted by *Nick2253*
> 
> For future reference, here is the service manual for your TV. It doesn't have your answer, but I thought you might like to have it:
> http://www.electronica-pt.com/index.php/component/option,com_remository/Itemid,34/func,startdown/id,8438/
> EDIT: As far as your situation is concerned, I think you have a leaking capacitor on your hands. At the very least, it's really cheap to replace a film capacitor (which is what that is. Either Capacitor C6552 or C6550 in the service manual, I can't tell which one is leaking).


I checked that link out and it is very helpful for disassembly. I believe that guide is telling me I do not need to remove all the silver metal. As for the capacitors, is that black stuff around those two capacitors definitely a leak? There is another glob of the same stuff a few inches to the right of it


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## animal0307

What silver metal are you talking about? Can you get some better pictures of that black stuff? I don't think that's a cap, Some times manufactures use a silicone like paste to keep components from vibrating.

Also could you take a picture of each PCB, Higher res/clarity the better.


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## animal0307

Googled your tv model and came up with this. (MediaFire downloadable PDF) Your TV is on the list under the 2008 US Models. (Thread that lead me to)

I did not read this, I skimmed it through it looking at the pictures and looks like something that may help.

Edit: That other PDF Nick linked to is ridiculous, It has complete break down of the TV.

And sorry for the double post.

Edit 2: And so I don't triple post. May want to check out the AVSForum and ask your question there.

Hope anything I've posted comes in handy, Good luck with your TV.


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## TH3_H4NGMAN

Quote:


> Originally Posted by *animal0307*
> 
> What silver metal are you talking about? Can you get some better pictures of that black stuff? I don't think that's a cap, Some times manufactures use a silicone like paste to keep components from vibrating.
> 
> Also could you take a picture of each PCB, Higher res/clarity the better.


The silver metal I'm referring to is the metal to which the PCBs are bolted to. Do I need to remove it? As for pics, here you go:
Big PCB

Smaller PCB

First black glob

Second black glob


These pictures are as close as I can get without a macro lens. Sorry if this picture size is a problem for anyone; I was just uploading them in a higher res as asked.


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## Nick2253

Those black blobs look a lot more like silicon than a capacitor leak, but I'm not 100% sure.


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## TH3_H4NGMAN

Quote:


> Originally Posted by *Nick2253*
> 
> Those black blobs look a lot more like silicon than a capacitor leak, but I'm not 100% sure.


That did seem like a lot of stuff for a capacitor leak. It is also greasy.


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## animal0307

It's it stiff but still soft? Kinda rubbery? If so I'm going to say its a silicone to isolate vibrations


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## TH3_H4NGMAN

Quote:


> Originally Posted by *animal0307*
> 
> It's it stiff but still soft? Kinda rubbery? If so I'm going to say its a silicone to isolate vibrations


It's pretty hard. I can squish it only if I push fairly hard.


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## latelesley

That black stuff is just glue - its not from a capacitor leak. The caps you are interested in are the electrolytic cans (the round ones - some with a Y shape in the silver top). Mostly they dry out and swell, and sometimes burst - but from a quick scan of your power board (the centre one) all looks ok. you could take the board out to check underneath (unplug the connectors, and just undo the black screws around the edge). I'd be interested in checking the soldering of the components at the top left of the board, around the grey transformer (thats where your HT circuit is for the backlights)

I'd also pop the metal cover off the board on the left (long green one) cos there might be some gubbins in there thats packed in. It looks like it connects the backlights to the supply,, and the small grey cable (7 wires) looks like it may be for brightness control. Just be careful as there may be more connectors plugged in at the other side of the green board under the metal shield.

On having a second look at the video - it could be the data cable not connecting right to the panel. - things to check there - the black cable from the green board on the right up to the top PCB, check that's secure. if it is, you might have to pop the cover off the top PCB and see if there is a connection to the panel hiding under there, as it may just be a loose data connection up there.

Hope that gives you things to work on.









L x


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## TH3_H4NGMAN

Quote:


> Originally Posted by *latelesley*
> 
> That black stuff is just glue - its not from a capacitor leak. The caps you are interested in are the electrolytic cans (the round ones - some with a Y shape in the silver top). Mostly they dry out and swell, and sometimes burst - but from a quick scan of your power board (the centre one) all looks ok. you could take the board out to check underneath (unplug the connectors, and just undo the black screws around the edge). I'd be interested in checking the soldering of the components at the top left of the board, around the grey transformer (thats where your HT circuit is for the backlights)
> I'd also pop the metal cover off the board on the left (long green one) cos there might be some gubbins in there thats packed in. It looks like it connects the backlights to the supply,, and the small grey cable (7 wires) looks like it may be for brightness control. Just be careful as there may be more connectors plugged in at the other side of the green board under the metal shield.
> On having a second look at the video - it could be the data cable not connecting right to the panel. - things to check there - the black cable from the green board on the right up to the top PCB, check that's secure. if it is, you might have to pop the cover off the top PCB and see if there is a connection to the panel hiding under there, as it may just be a loose data connection up there.
> Hope that gives you things to work on.
> 
> 
> 
> 
> 
> 
> 
> 
> L x


Thanks for your advice. I'll take a look at the things you mentioned in the morning.


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## latelesley

I've had a look at the manual - and you only need to check the cable at the top - no need to take the metal shield off - it looks like its part of the panel. Also check page 20 of the service manual too if you are removing the metal shield on the backlight PCB on the left - there's 3 screws under the shield you shouldn't touch - so check the manual









There is also a self diagnostic check thing on page 12 of the service manual - it might be worth checking to narrow down where the problem is.

Best of luck


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## TH3_H4NGMAN

I checked out all the connections and they seem solid, but I unplugged and replugged all of them just to be sure. I let the TV warm up for an hour and the flickering is now gone but the middle and left side of the panel are dark and the left side exhibits fairly severe motion blur. Is the panel damaged or is this still fixable?


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## animal0307

I'm gonna say that there is a bad board somewhere in it, most likely one of the driver board for the LCD.


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## TH3_H4NGMAN

Is that fixable?


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## latelesley

I think your panel may just have died.







if its blurring etc, that's to do with decoding of the signal - something's packed in. You could try a replacement BU Board (the right hand one with all the connections), but I couldn't guarantee that will fix it. It could be that board producing a bad signal, or the panel not decoding the signal right. And the panel isn't something that can be fixed DIY. I've damaged a couple of LCD screens in the past fiddling with the ribbon connections to the screens - the connections are hair thin and fragile, even touching them can damage them. I found this out trying to repair a laptop LCD panel that had lines down it, and thinking it was a bad connection, tried to reconnect with a little pressure on the ribbon. All that happened is it got worse.

So, you have 3 options -

1. new BU board

2. new panel

3 new TV

Sorry, but that's how it looks from here.









L x


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## latelesley

actually - having a think - it could still be a power issue - if you have a multimeter, you could check the voltages coming off the PSU (in the low tension side of course, avoid the live mains side). On page 86 of the PDF manual at the top right, you will see the connection to the BU board, you can use that to see where the 12V (reg12V) and 15V (unreg15V) and 3.3V supply is. now the unreg 15V may vary by a few volts, but the 12V and 3.3V should be pretty spot on.

The reason i'm thinking this, is the dark parts of the panel - that screams backlight issues to me, and possibly could be something in the backlight circuit pulling things down, a bad PSU, or back to my origin al theory of something bad in the BU board or panel.

It worth checking all the bases before writing it off.

sorry for the ramble, i'm not the most logical of diagnosers - I go down random paths!


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## TH3_H4NGMAN

Unfortunately I don't have a multimeter. I guess this thing is pretty much dead


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## Mergatroid

Top of the panel, under the metal shield is the tcon board. Remove the shield, open the connectors locking the ribbon cables, and also unlock the ribbon cables where they plug into the panel. Remove the cables and clean the ends. I use a burnishing brush to scratch them up a bit where I work. Use whatever you have at hand. Reinstall the cables and the shield and retest the TV. If you're still getting the same problem, try slightly twisting the panel (that is, push it forward at the top left and pull it back on the top right) to see if this makes a difference in the defective areas of the picture.

If it does, try cleaning the two cables a little better. If that doesn't help, some panels allow you to access the small circuit board across the very top of the panel under the chassis. In some cases you can remove a couple of screws and actually remove the top strip of the panel chassis. If you can do this, you can run the tv while gently prodding the ribbon cables that actually attach from this little board to the glass of the panel. Use something like a q-tip or other soft tool to gently flex the ribbon cables. If you find one that makes a big difference in the picture then unfortunately it looks like your panel has had it. The contacts between these cables and the glass sometimes go bad on LCD TVs. and there's not really much you can do to repair them.

On the other hand, if twisting the panel makes no difference (or very little) you may suspect the tcon board itself (the one the cables you cleaned plug into). Sometimes you can find these boards if you have the numbers off of them. A google for the panel manufacturer and the number from the tcon board will often turn up replacement boards.

There should be a sticker on the chassis of the panel saying who manufactured it with the panel number. Try googling it along with the number from the tcon board and/or the word tcon.

Remember, only suspect the tcon board if you're convinced the panel glass-connections are OK (doing the twist test). If it seems to clear up a bit when you twist the panel then it's likely not the tcon board.


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## bilalahmed

Hi Mergatroid,

Can you please look at the video in above link? My TV just started flickering like this since yesterday. I thought it might be due to cable signals or some interference but it behaves like this when playing Xbox or DVD. I tried to upgared the software but no use. also change resoluion to 1080i but it didn't resolve the problem. What will be the issue with the TV.
It is LG 50pk590-ze. Your help will be really appreciated. many thanks all of you who views this post.
Bilal


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## Electrocutor

LCD = Flourescent Backlight

That flickering looks to me like the tell-tale signs of dying flourescent bulbs. The question then, I suppose, is the problem actually the bulbs, the power supplying the bulbs, or the electronics controlling the power supply?

Bilalahmed's attempt to hijack the thread is definitely not the backlight and isn't related to your issue at all. It looks like his image is flashing an exact horizontal flip of the picture every so often. I'd suggest going through the setup and turn off each video feature "enhancement" one at a time until it stops doing that to see which one is causing it.

Likely there is a defunct chip in your TV and the board needs replaced. Otherwise, if the TV is new, just swap it for the same model where you got it.


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## Mergatroid

Quote:


> Originally Posted by *bilalahmed*
> 
> 
> 
> Spoiler: Warning: Spoiler!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Hi Mergatroid,
> Can you please look at the video in above link? My TV just started flickering like this since yesterday. I thought it might be due to cable signals or some interference but it behaves like this when playing Xbox or DVD. I tried to upgared the software but no use. also change resoluion to 1080i but it didn't resolve the problem. What will be the issue with the TV.
> It is LG 50pk590-ze. Your help will be really appreciated. many thanks all of you who views this post.
> Bilal


Wow, it looks like you're getting an image ghost flickering in and out for some strange reason. It almost reminds me of a vcr with bad tracking.

That is pretty bizarre. Congrats on coming up with something I haven't seen in an LCD TV before. It's not going to be a backlight as that would note give you the odd ghosted image (although it could account for the odd horizontal noise lines).

There is a board on the back of the LCD panel called a T-Con board. It is usually a small board at the top of the panel with a cable running to the main board, and small ribbon cable(s) plugging into the LED itself.

Both the main board and the t-con board can cause unusual image distortion faults like this.

Personally, I would first check the power board for any bad capacitors. If you have one or more vented capacitors on the 5V line, it can make the main board do some pretty funky things. The 5V is usually stepped down using a regulator to 3.3 or 2.2 volts to run some of the ICs, so any fault on the 5V line on the power board can feed through to the ICs on the main board. Also try unplugging any ribbon cables on the t-con board and give their tips a good cleaning. I might use a burnishing brush to scuff them up good (you could use a very fine emery paper). Just a couple of passes should be good.

If none of those help, and you've tried software and a factory reset already, you might want to consider looking for a main board on the 'net if you think the TV is worth it. I hear Walmart was selling a 42" LCD TV for $299 shipped today (it was on cnet) "deal of the day". Apparently it gets good reviews from owners. You might want to consider replacing it instead of repairing it depending on how much the board costs. Don't forget, this could also be a panel fault, there's no way to diagnose it 100% accurately without subbing some of the parts.


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## bilalahmed

thanks for your detailed reply. Which one is t-con board in the above picture? I opened the back cover yesterday and tried to check bad capacitor and looose connections. but no joy yet. I also unhooked ribbons from p101 to p204 andthen p201-203 and reseated them.
one thing more, when I press tv menu it appears uside-down like a mirror image of text. plzz help


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## bilalahmed

hI,

jUST AN UPDATE. I CHECKED LG WEBSITE FOR TROUBLESHOOTING THIS ISSUE. THEY SUGGESTED THAT IF IMAGE GHOSTING OCCUR THEN REPLACE HDMI CABLE WITH CO-AIXLE CABLE AND IT MIGHT SORT THE ISSUE OUT. AND INFACT IT DID. VERY HAPPY. IT TURNED OUT THAT THERE IS NO FAULT WITH TV, IT IS DUE TO CABLE CONNECTION FROM WALL TILL CONNECTOR.
ALL IN ALL, I AM HAPPY. THANKS EVERY ONE.


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## Mergatroid

That's odd. I had thought you tried it on multiple devices, with multiple cables. Are both your xbox and dvd using the same HDMI cable?


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## bilalahmed

Xbox, dvd and dv box are connected with their own separate HDMI cable. Yesterday when I switch the HDMI cable with scart /coaxile cable then picture become stable. after a while I reconnected HDMI cable and it was fine. no picture shaking or flickering or ghost imaging.
But today when I turned on TV it started again flickering and ghost imaging. I tried with scart cable but picture kept shaking. i tried everything i.e. switch off and rebooting evrything and remove all HDMI cables and then tried with scart cable. but no joy...
when I change the picture enhancement setting i.e. reduced contrast setting it stopped shaking though. what do you think what will be the reason????I thought problem is solved but it still
is there, Now what to do?/?
I rechecked all ribbons and reseated again but no use.I also used freeze spray on screen edges as suggested by some on youtube but no joy. How to check step by step troubleshoot. plzz help


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## Electrocutor

Quote:


> when I change the picture enhancement setting i.e. reduced contrast setting it stopped shaking though. what do you think what will be the reason


Sounds like either a bad or overheating chip.


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## bilalahmed

where would that be? which board? power supply, main board x board or y board???? which one?? how to get to that chip???
how to verify faulty board? how to isolate each board and check board, I mean after detaching board one by one.. can I get to the faulty board???


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## Mergatroid

You are confusing LCD with Plasma. LCDs don't have X and Y sustain boards.

The picture you uploaded is a picture of a Plasma TV chassis.

Do you have a Plasma TV or an LCD TV? This thread is about LCD, not Plasma. Plasmas don't have T-Con boards.

If you have a plasma, I can't help you much. I haven't worked on a lot of them (only a few). Mostly I've done firmware updates and replaced a few main boards and power boards.

I would recommend you take your TV into a shop and have it diagnosed.

FYI, you don't replace chips on these boards, you have to replace the entire board. Not many people have the skills or equipment to replace surface-mount ICs, and even diagnosing the fault to the exact chip can be next to impossible depending on how skilled the tech is (for example, an engineer at the company that makes the TV might have a good idea what's going on, but the average TV tech would tell you to replace the board).

You're asking for specific answers that the people here just can't give you. You have to substitute the boards to narrow down the fault, not just disconnect them. If you don't have boards to substitute then there's very little chance you'll be able to repair this yourself without purchasing them. Considering you don't even know what type of TV you have, I stick to my suggestion that you take it to a TV shop and have them look at it. Try and make it a TV shop that is familiar with your brand and model of TV.


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## roguetrip

For the sony:

The issue is IN the LCD panel. Depending on the type you maybe be able to disassemble the panel and see if the thin boards accross the screen is detachable from the LCD screen itself, if so try reseating them.

Usually its a bad or poor connection in the upper driver boards that t-con attaches to. It could be like something like the driver board physically warping and the cable or a component loosing connection as the set warms or cools. It could lead to permanently happening over time.

For the LG, your issue will be in the control board (sometimes a.k.a digital or logic boards) or a main board. I'd suspect the Main first. These boards do the processing, the rest is just output circuitry.

Good Luck.


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## bilalahmed

Thanks for your reply. I already have booked with someone to have look at it. This is LG plasma TV model number 50pk590. Sorry for the confusion. Its strange when you reduce the setting of picture enhancement then picture shaking, the white thin lines and offset imaging reduces and disappaers after a while.
On LG website they say if the picture shaking, or ghost/offset imaging occurs then it is due to bad connection in the cable from wall to DV box. LG also says that if the problem persists the it will be due to wiring in the house. As a matter of fact we had a electricity problem last montth when the safety switch went off and wasn't coming back on. Electricians soent all day but could find fault. Thay said there is a fault somewhere in the circiut. eventually they had to downgrade the fuse from 30 to 20amp after adjusting the wires in kitchen & dining areas.
I am suspecting it might be due to some interference. I will update today after the technician's inspection.


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## Cricky07

Please help Megatroid or anyone that could fix the problem.

Just got a TV from my friend because it was just sitting in his garage.

When I turn the TV it seems fine but when it goes the not programmed page with a LG logo (as seen in the picture) there is a horizontal line going to the logo.

I checked the PCB/PSU there are no Blown or leaked CAPACITORS.

I put the other board in the oven for just a while but still the problem is there.

I hope you could help me solve the problem.

Thanks


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