Samsung LN40A550 corrupted image

[tibimakai]

I have picked up this TV with supposedly green image.
It worked for me well for over a week.
I thought that is all well. Now when I was ready to sell it, the image got corrupted at bootup. It restarts a couple of times, until the image is good.
Sometimes it makes the screeching sound with the corrupted image. This sounds as a mainboard fault.
There it could be other issues as well? Capacitors maybe?
I have the same TV in my bedroom which works well after replacing capacitors in it. The panel is marked differently in the service menu.

[tom66]

Re: Samsung LN40A550 corrupted image

Main board BGA/ bad RAM, typically. Could also be a bad tantalum capacitor near CPU/RAM.

[tw2005]

Re: Samsung LN40A550 corrupted image

I've had something similar on a chinese cheapie 32" LCD. TV would run for random periods then suddenly screeching noises, green screen, messed up picture all scrambled and locked up.

That was dirty 5V rail from memory on the PSU, bad 100uf cap, well actually the cap was ok, the soldering was not. Was not soldered correctly, dry joint. That was an easy fix.

So bad cap / dirty power could be a possibility.

[tibimakai]

Re: Samsung LN40A550 corrupted image

Found two 1000uF/50V capacitors at the output on the power supply, that somebody already replaced with the wrong capacitors.
One of them had high ESR, the other one seemed fine.
Replaced them with correct Panasonic ones.
Right now, it seems like it's working great. I will monitor it for the next couple of days.