Samsung flat screen with scrambled picture

[stushug]

I have a Samsung LNT4071FX/XAA that has a scrambled screen when I first turn it on. The screen is usually green with vertical lines and a scrambled pattern. If I turn it off and then back on, it usually fixes the problem. It used to happened rarely, but now it happens every time I turn the set on. I swapped out the main board this morning, but the problem remains. What I've read on the net had me thinking it would be either the main board or the T-CON board. I'm assuming since I still have the issue after swapping the main board it's probably the T-CON board. Am I right? I posted a picture of the screen for reference. Thanks in advance for any help!

[JohnCT]

Originally Posted by stushug

I have a Samsung LNT4071FX/XAA that has a scrambled screen when I first turn it on. The screen is usually green with vertical lines and a scrambled pattern. If I turn it off and then back on, it usually fixes the problem. It used to happened rarely, but now it happens every time I turn the set on. I swapped out the main board this morning, but the problem remains. What I've read on the net had me thinking it would be either the main board or the T-CON board. I'm assuming since I still have the issue after swapping the main board it's probably the T-CON board. Am I right? I posted a picture of the screen for reference. Thanks in advance for any help!

That pattern usually indicates a bad TCON, yes.

But the *vast* majority of those I've actually seen were caused by a flaky LVDS ribbon cable. Try *gently* flexing the ribbon both at the main and at the TCON.

If the picture flashes or blinks when the ribbon is prodded, remove the cable and gently clean the contacts of the ribbon with a pencil eraser at both ends. Use a razor to sharpen the eraser to an edge that will clean the contacts as they tend to be recessed into the connector. Do not rub too hard lest you remove the plating.

Follow up with a q-tip and alcohol to remove the eraser residue. If you have any clear dielectric grease, a very thin film should be applied. Snap the ribbon in an out of the main and TCON a few times to clean the contacts on those boards. Never use WD40 in any electrical connector!

That fixed most of those early Sams with that issue.

John

EDIT: I reread your complaint, and if the TV always makes this pattern when first started and then clears up on cue, it's more of an electrical problem. If the ribbon cable isn't touchy, what I would try is preheating the TCON with a hair dryer before first start. If it runs clean with the board pre-warmed, I'd try a TCON. There's a long shot possibility it could also be an issue on the bonded address board at the screen itself, so when you preheat the TCON, try to keep the heat out of the area where it might also preheat the address board. The address board is kind of buried in the display frame but it's not air tight.

[damen]

Also, don't overlook the power supply caps. I've had them cause strange patterns and even squealing noises when first turned on from a cold start. Pay particular attention to the ones clustered near heat sinks.

[stushug]

I cleaned the connectors as you suggested and the set turned on without the scrambled screen. I will see how it behaves over the next few days before I claim success.