Samsung LNR408DX Negative Picture After TConn Replacement

[CrypticOne]

I have a Samsung LNR408DX/XAA that had a blown T Conn board. I had no picture and the pico fuse was blown. I replaced the board with a replacement and I have picture now but the colors are very wrong.

The company I purchased the T conn board was nice enough to send me another replacement board to test out in the TV to see if their replacement was defective. I should get it sometime next week but in the mean time I wanted to see if anyone had experienced this issue before and could offer any advice if the second t conn board also does the same thing.

Here is a short video showing the source playing and what the TV is displaying.

https://plus.google.com/112701116351...ts/PaVTmqWEkKj

Thanks in advance,

Cryptic

[freakaftr8]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

Possibly a wrong setting in the service menu? Were.the revisions the same on both boards?

[CrypticOne]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

They appeared to be exactly the same board. I don't see any options in the service menu that would apply.

Thanks,

Cryptic

[CrypticOne]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

I should add, I did a factory reset after swapping the boards to see if that would help.

[selldoor]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

These boards are often used in different sets with different size screens.
There should be a barcode label on it and the numbers should match exactly.
Sometimes you need to get into the service menu to tell the board what screen
you have.

[johnboy1313]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

Can you post a picture of the service menu?

[CrypticOne]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

The part numbers are slightly different at the very end but both boards should be LJ94-00701F.

I attached a picture of the two T conns and also the service section detailing the options in the menu. Not sure if you can point me in the right direction on what settings I should try.

Thanks,

Cryptic

These boards are often used in different sets with different size screens.
There should be a barcode label on it and the numbers should match exactly.
Sometimes you need to get into the service menu to tell the board what screen
you have.

[Maxstang]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

Gamma chip failure?

[CrypticOne]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

Where would that chip be typically found? Main board or on the panel itself?

Gamma chip failure?

[tom66]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

On T-con board

[CrypticOne]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

Well, That is good. May have just gotten a defective board. Are those the VGMA pads on the T conn?

Would it be helpful to pull the voltages?

On T-con board

[tom66]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

Yes, you can test VGMA voltages and see if they are OK or not.

[CrypticOne]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

I wasn't able to find all the points.

VGMA
2= 13.91
3= 12.96
4= 12.43
5= 12.2
6= 11.91
7= 11.7
8= 11.25
9= 7.83
10= 7.5
11= 4.1
12= 3.591
13= 3.47
14= 3.275
15= 2.97
16= 2.558
17= 1.567
18 = .8mv Wrong Pad?

Yes, you can test VGMA voltages and see if they are OK or not.

[tom66]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

That chip looks bad.
pic 1: your results
pic 2: what it should look like

Hard to tell, though.

[CrypticOne]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

Thank you all for the assistance. I got the replacement tcon and it was DOA with a blown fuse. I will contact the seller Monday. In the mean time I repaired the fuse on the original board and have the same image quality problems as the first replacement board.

So with two tcons doing the same thing; obviously both could be junk boards. Could the panel be bad or the main board? Power supply issues? Should I try another tcon or are there other things to test to determine the issue more clearly? Should I just junk the set?

Thanks,

Cryptic

That chip looks bad.
pic 1: your results
pic 2: what it should look like

Hard to tell, though.

[CrypticOne]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

I showed the pictures of the TV to someone who has some experience with TVs and he thought the panel was bad. Is there any way to test the panel directly?

[tom66]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

Yes it could be a bad panel. You can try checking the VONE/VOFF or VGH/VGL voltages on t-con; these are usually marked by test points.

[CrypticOne]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

VON 21.59
VOFF -5.19

Thanks,

Cryptic

[Glitcher]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

Did you test the fuse on the new tcon before or after you placed it in your panel? Theres a chance that your panel may be causing the fuse to blow just as in your original tcon board. I would say you probably have a bad panel causing the fuse to short.

[tom66]

Re: Samsung LNR408DX Negative Picture After TConn Replacement

VONE and VOFF are both OK. Not sure what else to suggest. Gamma voltages are a little iffy, but might be OK for this panel.