Flickering Horizontal Lines and other distortions on Samsung LN52A850S1FXZA LCD

[SurrealMustard]

I'm looking at this Samsung LCD and am having a tough time tracking down what's causing this issue. It's a bit difficult to describe, but what happens is that after it has run for a little bit, horizontal lines start rapidly flickering everywhere. As time goes on, it gets a bit worse and the bottom of the image also starts getting a bit stretched out too. The problem transcends inputs, video sources, cables, and TV-generated menus.

I tracked down a few other threads on this issue, but nobody ever nailed down a definitive diagnosis. The boards all look good, but there is a bit of brown stuff on the bottom of some capacitors; is that normal? Otherwise, does anyone know what could be causing this?

[dick_barton]

Re: Flickering Horizontal Lines and other distortions on Samsung LN52A850S1FXZA LCD

Those capacitors look as though the electrolyte has leaked out from the negative pin. Looks similar to when a battery leaks.
I would remove and test all of them for capacitance and ESR.

[SurrealMustard]

No dice

Those capacitors look as though the electrolyte has leaked out from the negative pin. Looks similar to when a battery leaks.
I would remove and test all of them for capacitance and ESR.

To expedite the process a bit, I subbed out the entire power supply board with a known-working unit, and the issue still persists. Any ideas for narrowing this down between the mainboard, TCON, panel, and such?

[dick_barton]

Re: Flickering Horizontal Lines and other distortions on Samsung LN52A850S1FXZA LCD

What make and model is the Tcon board?

[vinceroger69]

Re: Flickering Horizontal Lines and other distortions on Samsung LN52A850S1FXZA LCD

Does this model suffer with the bga soldering issue on the mainboard? like some other samsungs maybe try a little heat on the mainboard see if the fault appears quicker

[ReeceyBurger123]

Re: Flickering Horizontal Lines and other distortions on Samsung LN52A850S1FXZA LCD

Could be bga but first replace all the secondary caps on the Psu, slim line lcds like this get very hot and I dare say all the output caps are near failure. Then let us know after that.

[budwich]

Re: Flickering Horizontal Lines and other distortions on Samsung LN52A850S1FXZA LCD

since you replaced the PS board with a known working one, have you tried looking / cleaning the lvds cable running between the main board and the tcon. have you looked under the tcon "can"?
Is that your black tape on the lvds cable or some elses... :-)

[SurrealMustard]

Samsung

What make and model is the Tcon board?

I'm not entirely sure. I was able to get the cover off of it, and it appears that there's definitely some big chips on there (at least one of which is a Samsung) though.

Does this model suffer with the bga soldering issue on the mainboard? like some other samsungs maybe try a little heat on the mainboard see if the fault appears quicker

I don't remember for sure, but there are definitely some sizable BGAs, both on the mainboard and TCON.

since you replaced the PS board with a known working one, have you tried looking / cleaning the lvds cable running between the main board and the tcon?

Yes.

have you looked under the tcon "can"?
Is that your black tape on the lvds cable or some elses... :-)

The black stuff looks like black tape, but is actually some kind of vinyl stuff. I think it came like that from Samsung, but am not 100% sure.

[vinceroger69]

Re: Flickering Horizontal Lines and other distortions on Samsung LN52A850S1FXZA LCD

230X138mm/T1.2
https://www.shopjimmy.com/samsung-bn...-con-board.htm

[SurrealMustard]

Tee con!

230X138mm/T1.2
https://www.shopjimmy.com/samsung-bn...-con-board.htm

You're pretty sure that it's the culprit then?

[vinceroger69]

Re: Flickering Horizontal Lines and other distortions on Samsung LN52A850S1FXZA LCD

No not sure but i linked the shopjimmy picture so other more experienced members can see what ics are used on it as they may of had issues with this type of tcon odd faults like you have maybe hard to fault find as you have swopped the psu already it leaves the tcon or the mainboard or the lcd panel pcb? (not sure this will cause the issues your having though) or a bad lcd panel, im sure more experienced members will have ideas as im still learning but as samsungs suffer bga solder issues if this was my set i would probably try a mainboard myself to rule it out but thats me wait and see what others think first.

[syaoran123]

Re: Flickering Horizontal Lines and other distortions on Samsung LN52A850S1FXZA LCD

Do the lines appear on free to air tv?

[steviewonder]

Re: Flickering Horizontal Lines and other distortions on Samsung LN52A850S1FXZA LCD

I would suggest some freezer spray, and start with the Tcon, or alternatively, disconnect the tcon and run the the set for a while,and then switch off,quickly reconnect the Tcon,and try again.If the problems start again after a while,with the mainboard still hot,this would suggest the Tcon..Bit of fuzzy logic I know..A hairdrier can work wonders too, for time delayed issues such as yours...It's amazing how a hairdryer can narrow things down-and freeze spray.

[SurrealMustard]

Feel like giving up!

Do the lines appear on free to air tv?

I'd imagine so, since they appear everywhere else when the problem happens.

I would suggest some freezer spray, and start with the Tcon, or alternatively, disconnect the tcon and run the the set for a while,and then switch off,quickly reconnect the Tcon,and try again.If the problems start again after a while,with the mainboard still hot,this would suggest the Tcon..Bit of fuzzy logic I know..A hairdrier can work wonders too, for time delayed issues such as yours...It's amazing how a hairdryer can narrow things down-and freeze spray.

I don't have freezer spray, but what I do have is a room-temperature (65 degree) room, so I let the thing cool off overnight and then heated up just the mainboard with a dryer and then turned it on. No issues - neither immediately nor after some time. The next day, I did the opposite and heated up the T CON with the dryer, leaving everything else cold as I booted up the television. Still no issue.

This thing is just becoming too intermittent to effectively diagnose. I really don't know what to do anymore at this point.

[SurrealMustard]

New strategy

I'm going to try a new approach. Since it takes close to 3-4 days to get the problem to come back, I'm going to leave it on until it starts acting up and then try applying additional heat to see if that makes any difference. Stay tuned!

[ReeceyBurger123]

Re: Flickering Horizontal Lines and other distortions on Samsung LN52A850S1FXZA LCD

Keep us updated

[SurrealMustard]

Symptom still elusive!

Keep us updated

After leaving it running for about two days straight, the problem has not reemerged, so I heated up the mainboard and then the T Con board with a dryer to see if heat could coax the issue out of it, but this did not work and it appears to still be operating normally. The only difference between my trials and when it was originally showing the problem is that it is currently laying face down with the back cover off in a room temperature room instead of hanging on the wall with the back cover on.

Any other ideas beside applying time and heat?

[SurrealMustard]

Still working! What a novel problem to have...

Four more days of nonstop operation with the television face-down have been unable to trigger the problem (ironic that we're talking about a working item on a repair forum ). I really don't know what to do at this point because I have the funny feeling that if I call it fixed and put it all back together, it'll just start doing the same thing again, but it looks like there's no other choice, unless somebody has any new ideas.

[ReeceyBurger123]

Re: Flickering Horizontal Lines and other distortions on Samsung LN52A850S1FXZA LCD

Seems like Bgs issue to me likely on the Tcon.