New 40" LCD has a light spot. - AVS Forum
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post #1 of 13 Old 09-28-2006, 09:59 AM - Thread Starter
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The Samsung 40" LCD I purchased has a light spot between the middle and upper right corner of the screen.. Its not a white spot but the color is a bit lighter than the rest of the screen when displaying a dark image and/or black screen.. Its does not appear when watching DVD, TV or even with the 360 hooked up, not when showing colors, only when screen is black.. An example would be when I go into the menu and then exit, the briefly displayed black screen in-between transition from menu to TV shows the lighter area, as does any other time the screen displays black. I am not sure if this is a big problem or not.. Would they do anything about it? Fix it, replace it? I just bought the TV from Futureshop like 2 days ago and I also got the 4 year extended warranty with it.. Would they even take it back since my mom got rid of the original box already?? (I was furious with her..)

Any suggestions guys?
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post #2 of 13 Old 09-28-2006, 11:49 AM
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Read my post HERE
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post #3 of 13 Old 09-28-2006, 12:00 PM - Thread Starter
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Looks like we're in the same boat..So I guess this is sort of normal with LCDs?
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post #4 of 13 Old 09-28-2006, 04:08 PM
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Not sure how normal it is . . . I have three LCDs without your problem.
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post #5 of 13 Old 09-28-2006, 04:46 PM
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From the research I've done, the problem you are describing is called backlight leakage/bleeding. I found out it was a major issue with some early Dell LCD monitors.

My 32" Sony KLV-32M1 LCD TV had this problem when I first got it a year ago. There were 4 palm-sized "blotches" around 6" from each corner of the screen. They were most noticable in dim ambient light and when the set was displaying a blank black screen. It drove me nuts when I was watching movies with dark backgrounds and shadows.

I hypothesized that the cause of the problem was due to localized pressure points on the LCD panel which displaced some of the liquid crystal matrix underneath. I came up with this idea because if you ever pressed against an LCD screen with your finger, you would notice it turns white where you touch it. The same could be happening if there is uneven stress on the panel assembly (as a result of shipping?).

With this hypothesis in mind, took a microfiber cloth and physically "massaged" the screen to even out any stress points. I applied firm pressure but not excessively so as to not damage the screen. I kept one hand on the back of the TV to counter the pressure of the other hand. Lo and behold, the blotches disappeared!
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post #6 of 13 Old 09-28-2006, 06:13 PM
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Quote:
Originally Posted by kontai69
From the research I've done, the problem you are describing is called backlight leakage/bleeding. I found out it was a major issue with some early Dell LCD monitors.

My 32" Sony KLV-32M1 LCD TV had this problem when I first got it a year ago. There were 4 palm-sized "blotches" around 6" from each corner of the screen. They were most noticable in dim ambient light and when the set was displaying a blank black screen. It drove me nuts when I was watching movies with dark backgrounds and shadows.

I hypothesized that the cause of the problem was due to localized pressure points on the LCD panel which displaced some of the liquid crystal matrix underneath. I came up with this idea because if you ever pressed against an LCD screen with your finger, you would notice it turns white where you touch it. The same could be happening if there is uneven stress on the panel assembly (as a result of shipping?).

With this hypothesis in mind, took a microfiber cloth and physically "massaged" the screen to even out any stress points. I applied firm pressure but not excessively so as to not damage the screen. I kept one hand on the back of the TV to counter the pressure of the other hand. Lo and behold, the blotches disappeared!
As Fiddle linked, I too have this problem on my 46" XBR. If anyone can confirm this to be a workable solution, I'll definitely give it a go. However, I'm hesitant to try this on a $4,000 LCD. Could it possibly be the screws on the rear of the assembly being overtightened? I see two that are right in the corner. One looks remarkable tighter (or looser, depending on the screw you look at) then the other. If this problem is as pertinent as you say in former LCD's, and it's most prominent in the corners, could one (or both) of these screws be an "adjustment" to allow them to fix this annomaly? Or perhaps the extra screw is just to hold the glass bezel in place.

Just my 1.4 cents (after taxes)
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post #7 of 13 Old 09-28-2006, 06:37 PM
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A closer investigation shows a phillips screw at each corner that appears to tighten the front bezel on (probably for easy swapping of colors) and a recessed "star" screw (the correct word for this type of screw head is eluding me) that I believe is what actually holds the TV case itself together. A much closer look with the lights turned down and a pure black screen shows a more subtle (though larger) patch imminating from the lower right corner as well (perhaps the TV was "torqued" when it was delivered/setup). I for one know that if I can't "wipe" this off, it will be going back to the store. Anyone else taken a closer look and noticed similar light patches?

Just my 1.4 cents (after taxes)
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post #8 of 13 Old 09-28-2006, 07:44 PM
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Uneven backlighting is very common on many LCDs. Some sort of uneven backlighting is present on most LCDs I've looked at critically - some people just seem not to notice it and so claim the effect doesn't exist.

My laptop's LCD, for example, does this. So did the Samsung 4092 one of my co-workers recently purchased.

It's an inherent limitation of transmissive displays that create black by blocking light. If every portion of the screen doesn't "block" as well, you get this effect.

I love HD...and I hated that Anti-Consumer format war.

Now that we can move on... Blu-ray > Digital Downloads!
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post #9 of 13 Old 09-29-2006, 03:18 AM
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Quote:
Originally Posted by tdavis21484
Uneven backlighting is very common on many LCDs. Some sort of uneven backlighting is present on most LCDs I've looked at critically - some people just seem not to notice it and so claim the effect doesn't exist.

My laptop's LCD, for example, does this. So did the Samsung 4092 one of my co-workers recently purchased.

It's an inherent limitation of transmissive displays that create black by blocking light. If every portion of the screen doesn't "block" as well, you get this effect.
If this is the case, and I believe it may be, there may be a solution. Many newer LCD have an adjustable backlight (some call the 'feature' Energy Saver"). Most default setting are very high. If he has not already done so, he could turn down the backlight and see if the problem goes away or at least lessens.
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post #10 of 13 Old 09-29-2006, 04:20 AM
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Quote:
Originally Posted by Nmlobo
If this is the case, and I believe it may be, there may be a solution. Many newer LCD have an adjustable backlight (some call the 'feature' Energy Saver"). Most default setting are very high. If he has not already done so, he could turn down the backlight and see if the problem goes away or at least lessens.
While that might lessen the visibility of it (as both portions of the screen approach total blackness, they should begin to meet at some point), I'm not willing to sacrifice proper black levels and dark level detail (and I suspect the majority of the community with LCD's feels the same way, especially at this price point). That's kind of like the old doctor joke where the patient says, "It hurts when I do this doc", and the docot says, "Well, don't do that." ;)

Just my 1.4 cents (after taxes)
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post #11 of 13 Old 09-29-2006, 04:27 AM
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I own three LCDs. Granted none of mine display this problem (at least not that I notice). I have reduced the backlight on my TV and have found that doing so INCREASES black levels (deeper, richer blacks) while not harming detail.

Remember too that most LCD owners agree that "out of the box" settings are generally too high and require adjustments.
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post #12 of 13 Old 09-29-2006, 05:35 AM
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Quote:
Originally Posted by Nmlobo
I own three LCDs. Granted none of mine display this problem (at least not that I notice). I have reduced the backlight on my TV and have found that doing so INCREASES black levels (deeper, richer blacks) while not harming detail.

Remember too that most LCD owners agree that "out of the box" settings are generally too high and require adjustments.
I totally agree that the settings need to be toned down out-of-the-box, but I've already done that and achieved very good black levels and detail, however, I still perceive these light spots. I guess what I should have said was that I could tone down the backlight a little more, but that I would begin to lose detail at that point.

Just my 1.4 cents (after taxes)
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post #13 of 13 Old 09-29-2006, 06:09 AM
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Gotcha. I misunderstood and thought you did not want to adjust the backlight settings at all. I agree with you, if you have achieved good black levels and detail you should not adjust further.
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