Samsung LN-S4695D Vertical Line

[mmartell]

Two inch green vertical line running down the middle. Otherwise works fine.

I can get this set cheap. Does this sound like a bad panel or a tab bonding issue that has a chance of being repairable ?

[tom66]

Re: Samsung LN-S4695D Vertical Line

90% bad panel, 10% chance could be tab bonds.

[mmartell]

Re: Samsung LN-S4695D Vertical Line

Ok thanks tom.

[mmartell]

Re: Samsung LN-S4695D Vertical Line

So what do you want for $25 ?

Image looks excellent at startup then within a couple of seconds you can see a band developing until in the last pic it becomes solid. Total time - under 5 minutes.

Seems to happen too fast to be heat related. T-Con capacitor ?

[tom66]

Re: Samsung LN-S4695D Vertical Line

Tab bond quite possibly. $25 is OK if nearby, minimal fuel cost, take a chance, you can probably sell the boards on and break even...

[mmartell]

Re: Samsung LN-S4695D Vertical Line

I already have it. Those pics were taken in my basement

So these symptoms point to possible tab bond and not other hardware ? Will look into it.

[tom66]

Re: Samsung LN-S4695D Vertical Line

Yeah t-con or power supply would cause global fault not single bar.

[mmartell]

Re: Samsung LN-S4695D Vertical Line

Ok thanks again tom.

[mmartell]

Re: Samsung LN-S4695D Vertical Line

Did someone say these tabs get hot ??

I've disassembled the unit to get to the tabs and these puppies get hot. Interestingly I found that gently blowing across the top of the affected tab makes the symptoms go away.

So I have a thermal problem that is creating a mechanical problem.

Suggestions ?

[budm]

Re: Samsung LN-S4695D Vertical Line

Yes, the IC modules on the flex board do get hot so do not run without the frame in place for more than 2~3 minutes, the frame is used as the heat sink.
https://www.badcaps.net/forum/showthread.php?t=25371

[mmartell]

Re: Samsung LN-S4695D Vertical Line

Had no idea that frame piece was a heatsink. I really did look at it after I took it off and said to myself "now what is the purpose of this design" ?

Thanks for pointing it out, bud.

[mmartell]

Re: Samsung LN-S4695D Vertical Line

So you recommend folding the pad around the corner so it makes contact with both the face and the top of the panel ?

And if you put on only affected tab then wouldn't the heatsink capabilities be diminished for the rest of them due to slightly higher spacing ?

[mmartell]

Re: Samsung LN-S4695D Vertical Line

I harvested some silicone thermal pads from a non-functioning Airport Express and placed them on the tape (3 pad thickness) and am getting much better results but over time the metal frame heats up noticeably (all around the screen not just the affected area) and the symptoms reappear, though not near as bad as before. I can only guess that fully reassembling the unit will only make matters worse.

[budm]

Re: Samsung LN-S4695D Vertical Line

I put the thermal transfer pads on all the tabs, the heat from the IC are transferred to the frame better with the transfer pads. It is about a year now since I did the repair on the two 52", they are still running.

[mmartell]

Re: Samsung LN-S4695D Vertical Line

Well I can tell you the whole metal bezel frame as well as the tcon cover is very hot to the touch, at the point where you would likely pull your hand away if it were any hotter.

Not sure if that's normal for these sets or not.

But it runs pretty good now, seems to have helped to stand it up as opposed to laying it flat as well.

[budm]

Re: Samsung LN-S4695D Vertical Line

The lamps also generated lots of heat also, as you can see the construction of the LCD panel assembly, no ventilation for the heat built-up inside the panel at all.

[mmartell]

Re: Samsung LN-S4695D Vertical Line

Is there any reason a person shouldn't (carefully!) drill some well places ventilation holes on the top of the metal frame to facilitate TAB heat extraction ?

[tom66]

Re: Samsung LN-S4695D Vertical Line

Potential contamination of the tabs from external sources of dust, or moisture. It won't matter much. Better would be some fan cooling system for them, but there is so little space...

[mmartell]

Re: Samsung LN-S4695D Vertical Line

Ya was thinking there's a little room where the panel ribbons go from the tcon. Still no real place for that air to vent except what can escape due to the metal bezel/frame not being a perfect seal. Will have a look when I get home.

[mmartell]

Re: Samsung LN-S4695D Vertical Line

Set mostly back together. The strip which was causing the problem (grey in the pic above) no longer reverts to that however it seems to be a darker shade than the rest of the raster. More importantly there is a noticeable "tearing" of the picture in that area depending on content.

Is that still a heat issue or has permanent damage been done ? Or is their possibly some cold solder joints near the tab itself ?