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Electronics => Repair => Topic started by: edy on February 15, 2016, 06:08:49 am

Title: Image sticking/persistence Samsung LCD
Post by: edy on February 15, 2016, 06:08:49 am
I have a Samsung LCD TV from 2008 which is starting to show significant image sticking. Some history on this TV... I had to change the caps on the TV power supply only a couple years in and have had no other  issues since. (Famous power on clicking issue)

But I just started to notice the stuck ghost recently, and it only takes a few minutes to stick. Eventually it goes away once I resume watching a moving picture. For example, if I pause TV or have a menu up for a couple minutes, when I jump to another channel or resume playing, I see the previous image faintly still on the screen depending on how bright the image and colors.

Any idea what is going on, what could be the culprit? Remember the ghost image only needs a minute to form... not hours like you hear from image burn.
Title: Re: Image sticking/persistence Samsung LCD
Post by: wraper on February 15, 2016, 07:16:18 am
Try this test (requires native resolution) http://www.lagom.nl/lcd-test/inversion.php (http://www.lagom.nl/lcd-test/inversion.php)
probably positive and negative voltage applied to the pixels (polarity is being inverted on the each refresh) are not equal.
Any image post processing preferably should be disabled to not mess up the test.
Title: Re: Image sticking/persistence Samsung LCD
Post by: bktemp on February 15, 2016, 07:38:41 am
It could be the VCOM/gamma buffer or some other local power supply for the LCD panel. They are all located on the TCON board.
Title: Re: Image sticking/persistence Samsung LCD
Post by: amyk on February 15, 2016, 11:06:22 am
Do you see any smearing in moving scenes? I agree with the others here, seems like Vcom isn't right or perhaps not sourcing enough current.
Title: Re: Image sticking/persistence Samsung LCD
Post by: edy on February 15, 2016, 02:00:10 pm
Normal TV seems ok, at least for now. Maybe not bad enough yet to notice. I just don't want to risk if I neglect it until it's too late and end up having more damage.

I am not surprised that it could be a power supply issue. This era of Samsung was notorious for it, and I was affected by the "power on clicking" fiasco that was class action settled. Except being in Canada I was out of jurisdiction and just changed the faulty caps myself for $5 and swore never to buy another Samsung again.

So this 2008 TV should have died 2010 and now it is 2016. Perhaps time to look at all caps again?