Samsung LN-T4661F & LN-46A550P3F White Background

[pauldow]

On both of these sets I have a white background, but the image does faintly appear on the screen. Is this a sign of bad T-Con boards?

The LN-T4661F initially just had a bad TAB connection. I took off the LCD frame and was able to find the bad one. I added a heat sink pad, but there's no screw at that corner to press down in that area. I wasn't thinking, and I lifted the metal frame while the set was on. The image went white, but then back to normal. I quickly unplugged it, but now it always has the white with a faint image. Did I probably fry the T-Con, or is the whole thing scrap?

I don't have a history on the LN-46A550P3F since I found it at the trash. The image looks similar to the other set though.

Thanks for any assistance,
Paul

[Sevenqi]

Re: Samsung LN-T4661F & LN-46A550P3F White Background

Check if the tab bond driver board has potentialmeters, if yes, check if one dropped or loosed connection.

[pauldow]

Re: Samsung LN-T4661F & LN-46A550P3F White Background

Thanks for the suggestion, and sorry for the delay replying. Too many squeaky wheels around here lately.

Are these what you mean when you say "tab bond driver board"?
I don't see any pots on them. In the photos, I left the heat sink pads on them.

[budm]

Re: Samsung LN-T4661F & LN-46A550P3F White Background

Thanks for the suggestion, and sorry for the delay replying. Too many squeaky wheels around here lately.

Are these what you mean when you say "tab bond driver board"?
I don't see any pots on them. In the photos, I left the heat sink pads on them.

Those are the T-CON boards.
How about the pictures of the screen shot so we can see what the pictures look like, you may have GAMMA Voltage reference problem which you can verify by checking the GAMMA Voltages at the test points on the T-CON board.

[Sevenqi]

Re: Samsung LN-T4661F & LN-46A550P3F White Background

Those are the T-CON boards only.
What I meant is the circuit boards (there are two left and right side) attached the panel, check the boards for the potentialmeters for the LN-T4661F. LN-46A550P3F should not have potentialmeters on these two boards, please replace the GAMMA IC.

[pauldow]

Re: Samsung LN-T4661F & LN-46A550P3F White Background

I really have to stop hopping between projects.
I had only turned the sets on without a picture source. Now that I used a Blu Ray disk, I see the symptoms are quite different than just a white screen.

The first image (IMG_4696) is from the LN-T4661F.

The second one (IMG)4695) is from the LN-46A550P3F

Sorry about leading you on the wrong path.

[budm]

Re: Samsung LN-T4661F & LN-46A550P3F White Background

https://www.badcaps.net/forum/attach...8&d=1454030854
This one is more likely have bad GAMMA ref Voltage IC.
Same for the second picture.
You need to take the GAMMA Voltage readings.

[pauldow]

Re: Samsung LN-T4661F & LN-46A550P3F White Background

So it doesn't look like I'm not taking your advice, here's a progress report on what I've done with these sets. Well, progress isn't quite the proper word.

I looked at replacement T-Con boards, and they run over $50 for each of them, so I thought I would try going with the repair kits sold online at a but under half that price. They have a very small 48 lead circuit. (I think that's the gamma buffer/regulator.) On the first one I tried, I didn't cut through the leads on the IC, and I pulled a trace of the PCB. Strike one.

On the second one, I was more careful, and I was able to remove the circuit fine. I got it cleaned up, and soldered back on, but I noticed that I was a bit off on alignment in one direction. I looked through a magnifying glass, and thought I could still see some space between pins. Powered it on, and smoked it.

Well, I got a bit of an education soldering those tiny circuits.