Problem with blacks on Panasonic VT50 - AVS Forum
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post #1 of 9 Old 04-02-2013, 01:49 AM - Thread Starter
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Hi All,

I have a TH-P55VT50A that's only a few months old and I've noticed that on full black screens e.g selecting any input with no source connected, there appears to be alternating light (grey) coloured lines mixed with the black.
The lines appear to be 1 pixel high so you have to be standing quite close to the screen to notice it but since noticing this behaviour it's hard not to focus on it. It's as if there is some form of interlacing effect going on. I also notice it on the black top and bottom bars watching letterboxed content.

I can only imagine that without these lines the blacks would be much darker.What's strange is if you move your head towards and away the screen the lines appear to shimmer.

The behaviour Is most evident in a dark room.I've tried setting the picture mode to Dynamic, Normal, Cinema, THX, THX bright room and game but the shimmering lines remain (all other settings are at their defaults).

Unfortunately I can't take a photo of it without everything coming out as black.

I've tried comparing it with an another panasonic plasma (ST50) in store but in a bright store environment it's hard to tell.Is this normal?

I expected that with no signal you would just see black. Any ideas?ThanksVas
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post #2 of 9 Old 04-03-2013, 08:52 AM
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Screens with no signal input are meaningless.

Tony
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post #3 of 9 Old 04-03-2013, 05:23 PM - Thread Starter
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Hello,

I understand that examining the screen with no inputs may be meaningless but it did easily highlight a behaviour I am seeing elsewhere such as full black parts of an image (or menu background). I also see the same shimmering lines when I've used the AVS HD 709 calibration images (MP4 versions) that are referenced here :

http://www.avsforum.com/t/948496/avs-hd-709-blu-ray-mp4-calibration

Whenever there is a full black section/background I can see these lines.

I initially thought it may have been interference so I unplugged all inputs and checked the TV's own menu backgrounds and saw the same effect.

The TV is plugged into a UPS so I tried plugging it into a separate standalone power point with no change.

Thanks

Vas
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post #4 of 9 Old 04-04-2013, 12:16 AM
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I know what you're talking about, mine has the same "issue". Originally mine were green lines that look like they're scanning upwards, but now they're grey. The scanning is not noticeable at normal distances, but as you said, it's light coming out of the panel which is making the blacks brighter than what they should be. I've asked before to see if it's just a normal part of the display, but no one else confirmed seeing it and made it sound settings based.

See this post (second paragraph) that I made and scroll through the page at the replies:
http://www.avsforum.com/t/1408338/official-panasonic-vt50-owners-thread/7170#post_22493804

I wish some others with a VT50 both calibrated and not could chime in if they can see the same thing. Glad to hear i'm not the only one though.

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post #5 of 9 Old 04-04-2013, 05:56 AM
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I own the New Zealand version of the 65VT50. These grey scanning lines also appear on mine but are not there on pro1,2 and cinema. They are present on all other presets including thx.

In my case they actually improve the blacks and mask mostly the IR or Black screen screen grey blobs that I see when they are not there.

The pro and cinema presets are noticeably higher in black. Best way to see the difference is with letterbox bars. With no scanning lines in pro they blend less with the bezel.

If you are on a NA model and have this effect in all modes I think you are winning rather than loosing, and wish I could have the better blacks on the pro modes.

I will be trying a home calibration when my colorimeter turns up. I will reply again if the situation changes.
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post #6 of 9 Old 04-04-2013, 03:37 PM - Thread Starter
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Cool,

That does sound promising. Thanks for your feedback.

Vas
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post #7 of 9 Old 04-05-2013, 05:56 PM
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It would also be interesting to know if your USA version has these lines in all presets including the pro ones? I have heard ours are stuck in low panel brightness setting on the pro. We do not have the panel brightness setting option. If you set yours to low maybe the lines would disappear.
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post #8 of 9 Old 04-10-2013, 07:18 PM
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I see something like this in all modes on an ST60 and I am in the United States. This is the first plasma I've owned so I'm getting used to its quirks. I can't notice any impact on the blacks from my couch and I can only see these lines when my eyes are a few inches from the display. I tested it on a couple inputs but the easiest way to tell was to actually display a 1080p black image from my computer which is also hooked up to the TV through HDMI. The actual fluctuation is so slight that the difference between black and off from a distance is not noticeable.

I have not tried running a black image through the TVs built in slideshow, but I may. I expect it to behave the same.

my NADs are new
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post #9 of 9 Old 04-18-2013, 12:25 AM
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Just commenting on this with regard to the ST60, but perhaps other plasmas as well. I wonder if this isn't somehow part of a precharging the TV does to ensure that the pixels displaying black will quickly respond to a demand to produce a much brighter color. I'd love to know more about how the panels are driven but the "scan lines" in the blacks may be deliberate for that reason, I definitely want to go stare at some different screens.

my NADs are new
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