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Pan TH-42PHD7UY Black level changing - Page 15  

post #421 of 449
It is the other way around: 50" has square pixels, 42" has rectangular.

It doesn't reflect poorly on you, the point is that the difference in shape is significant, which we wouldn't have known without you. Thanks!
post #422 of 449
Wonder if the spacing between pixels have an effect? Is this a constant among the different panels?
post #423 of 449
I don't see how it has anything to do with the size or shape of the pixels. Regardless of what the Panasonic guy said. :) It has to be in the electronics that are driving the entire display. It is some sort of global managed brightness averaging type thing. That sucks for those of us who don't want a 50" panel.

For kicks, the I'll try that menu blue test on a consumer 50" to see if it has it or not too.
post #424 of 449
The TH50PX50U consumer model shows a change in black level w/ the 'blue menu' test and ESPNHD's side bars... I notice it on my set.. I seriously doubt the shape of the pixels has anything to do with it!

-J
post #425 of 449
Quote:
Originally Posted by Kevin C Brown
I don't see how it has anything to do with the size or shape of the pixels. Regardless of what the Panasonic guy said. :) It has to be in the electronics that are driving the entire display. It is some sort of global managed brightness averaging type thing. That sucks for those of us who don't want a 50" panel.

For kicks, the I'll try that menu blue test on a consumer 50" to see if it has it or not too.
There may be a way to disable the screen saver function that lowers the black level. You would need to talk to Panasonic Tech support or PM techniwizard.

-- Rich
post #426 of 449
Is this a DC Restoration issue?

As mentioned in the CNET reviews for the 37PHD8UK (and as pointed out once before in this thread by someone else), CNET attributes this changing black level problem to a "DC Restoration" (aka Black Clamping) problem. As stated in their review:

"The Panasonic TH-37PHD8UK is a stellar performer with only one real exception. Black-level performance on this panel is first-rate, except for the fact that if floats blacks a little from dark to bright scenes, which is something we'd like to see Panasonic improve. In other words, the brightness of its "black" fluctuates depending on whether other areas of the screen become brighter. This flaw contributed to its Poor score in DC restoration in the geek box."

CNET defines DC Restoration as follows:

DC restoration
Geek box term. Measurement of how well a television is able to maintain a consistent color of black regardless of the brightness of the rest of the image.

CNET's "Geek Box" goes into further detail on how this is tested:

DC restoration
Example result: "All patterns stable"
Here we use the series of PLUGE (Picture LineUp Generating Equipment) patterns from the Avia disc to determine how well the TV is able to maintain a consistent color of black as the average overall brightness changes--essentially, whether black gets brighter or darker along with the rest of the picture. After setting the black level with the Black Bars + Log Steps pattern (1:3), we check whether the moving stripes change in intensity or remain stable when displaying other patterns.
Good: No change on black bars + half white (1:6) or Black Bars (1:4) (denoted by "All patterns stable")
Average: No change on black bars + half gray (1:5) (denoted by "Gray pattern stable")
Poor: Change on black bars + half gray (denoted by "No stable pattern")

Curiously, in CNET's original review of the 42PHD7UY (the model that I have), they listed DC Restoration as "Good - All paterns stable", which would indicate that in at least their review model, they did not see it. In the review for the consumer version, however (the TH-42PX50U), DC Restoration was listed as "Poor - no patterns stable". I have not done the PLUGE test they decribe yet to see if I can duplicate the problem using that test, but as I have mentioned in a number of earlier posts, I have seen the effect generally in my 42PHD7UY (and by the "effect" I mean blacks getting a shade lighter as a dark scene gets lighter)

I hope some others on this forum with more technical knowledge than (which would not be saying much) can confirm that this is the cause of the issue we are complaining of, and from there we might be closer to a confirmatory test, perhaps figuring out why the 50" sets don't seem to have the issue (or not as much), and perhaps whether it has anything to do with pixel shape. Even if we are no closer to a fix, at least we might be able to more accurately describe the matter as "the DC Restoration problem" rather then "black-level shifting problem", which for some reason still keeps getting confused with the screen protection/power supply "features"/theories, which (I think) we have determined are not the cause of this problem.
post #427 of 449
Quote:
Originally Posted by R Harkness
For what it's worth...

I believe I saw the black shift problem on the Panny 65" Onyx, wich is a 7th gen panel.

I have watched many, many hours of material on the Panny 8gen 50" model (lots of letter-boxed movies) and have never seen the black shift issue.
Rich, did you upgrade from your 4th gen 42"? (I haven't been paying as much attention to this form of late.)
post #428 of 449
Quote:
Originally Posted by Kevin C Brown
I don't see how it has anything to do with the size or shape of the pixels. Regardless of what the Panasonic guy said. :) It has to be in the electronics that are driving the entire display. It is some sort of global managed brightness averaging type thing. That sucks for those of us who don't want a 50" panel.

For kicks, the I'll try that menu blue test on a consumer 50" to see if it has it or not too.
I'm inclined to believe the NJ guys, as they are in contact with Japan engineering on this stuff. (Some post here too, such as Techniwizard.) It sounds like they're saying what you're saying: the algorithm used in the electronics of the panel interacts negatively with rectangular pixels. Fixing it requires reworking the electronics, not replacing a capacitor like they did with the s-video problem. In other words it isn't fixable until a new generation of panels comes out. Too bad it wasn't addressed in the 8 series.

I didn't want a 50" inch either, but this issue forced me to upgrade to one and I've been suffering with it ever since :D. It isn't as big as I thought it would be.
post #429 of 449
Lets see if I can be of help here. From my experience I owned the two piece plasma with the media receiver seperate from the display (consumer model). I went through warranty with a local service center. To make a long story short we tested three media receivers and two out of the three had these symptoms on the same display. I had dvd's that I recorded that I knew would reproduce this problem and I could do it easily with subtitled movies. When the white subtitle would turn on the background would change brightness but not all scenes. It has something to do with certain colors. Also I could see it when guests on Leno would move there hands and brightness would change on top of screen on certain colors not all the time. Ok now why would one of three media receivers not do it. Well I have two thoughts here. Maybe Rich B maybe correct that you have to turn off screen saver function through the service menu which I didn't try because I could not find anywhere how to access this(not all service menu access is stated in faq). But don't you think there would have been a memo about this by now? The other thought is that the problem is in the video processing and one way to solve it is to get a external video processor like the DVDO. From my experience I don't think the problem is in the display itself. I've stated before that I couldn't live with it was annoying to me. But others can live with it as we've read about here. These are just my opinions.
post #430 of 449
Quote:
Originally Posted by oldcband
The other thought is that the problem is in the video processing and one way to solve it is to get a external video processor like the DVDO. From my experience I don't think the problem is in the display itself. I've stated before that I couldn't live with it was annoying to me. But others can live with it as we've read about here.
I ran the 42PHD7 with an iScan HD, so adding a video processor to the mix didn't address the problem. That tells me that the problem isn't in the scaler or deinterlacer, since I was sending deinterlaced native resolution into the display.

I couldn't live with it either.
post #431 of 449
rm, it's not a "DC Restoration" issue. Lot's of threads about this if you do a search, but the specific term "DC Restoration" only applies to CRTs that don't have beefy enough power supplies to properly drive the tube. For the Panny (and other) plasmas, it's some type of electronics thing that's controlling the overall brightness of the panel. Same effect, more or less, but different cause.


So that would mean that the 50" 8uk is unique? OK, I' have to get my butt in gear. I have found a local place that is supposed to have the commercial models. Now I'm curious if they have a 50" I can test. :)

Obviously then, if the consumer model has it but the pro model doesn't, it's not just a question of square vs rectangular pixels.
post #432 of 449
Great, so the 8UY has the same issue? I thought the issue died with the 7UY :(
post #433 of 449
Drats. There is a local place that sells the 8uk displays. But they don't have a showroom. None on display.
post #434 of 449
I wanted to post an additional piece of info.

The lastest Home Theater Magazine notes this problem for the 42px500u. Sort of. :)

Nothing in the text, but it you look at the measurements section:

Quote:
-> DC Restoration (poor, average, good, excellent):
Good (poor in Vivid and Standard modes)
And they calibrate to 6500K by using the service menus. So after proper calibration, it is better (but not "excellent").

Now that I know that HT Mag tests for this, I'll have to go back and check out previous reviews of other plasmas. :)
post #435 of 449
I wonder what 6500K corresponds to in the color temperature settings. My 42PHD8UK only gives qualitative choices: normal, warm or cool.
post #436 of 449
Very likely 6500K is considered normal as that is specified as the color of daylight. Cool is a higher reference temperature, warm a lower.
post #437 of 449
Hi there, I had 3 PHD8's (UK models) and all had the contrast/brightness flicking issue......AVSales (the retailer I dealt with) evenually got the response below from Panasonic uk:

Received a reply from Panasonic. The effect you have seen is caused by the operation of the ABL (auto beam limiter) on the plasma. The ABL is designed to offer the viewer the best possible picture overall and helps to reduce deterioration of the panel and panel life.

It appears this is triggered occaisionally in some films.
-------------------------------------------------------------------------------------------------------
So its a "feature" not a fault.........got a Pioneer 436 now as I couldn't hack this fault as well as dead pixels.....great set other than that though.
post #438 of 449
Quote:
Originally Posted by blackeyepurple2
Hi there, I had 3 PHD8's (UK models) and all had the contrast/brightness flicking issue......
What size?
post #439 of 449
Quote:
I wonder what 6500K corresponds to in the color temperature settings. My 42PHD8UK only gives qualitative choices: normal, warm or cool.
6500K is usually the warm setting. This is from the calibrations given in mags that properly calibrate their displays like HT mag, S&V, TPV, WSR, etc. Additionally, when I first got my Tosh 32" HDTV capable CRT, I asked Toshiba directly what setting to use to get closest to 6500K. They said warm.
post #440 of 449
>> Hi there, I had 3 PHD8's (UK models) and all had the contrast/brightness flicking issue......

> What size?

Good point, as a lot of people who've looked at or owned the 50" say that it doesn't have this ... feature. :)
post #441 of 449
Quote:
Originally Posted by pstrisik
What size?
42"
post #442 of 449
Quote:
Originally Posted by blackeyepurple2
42"
Thanks. Just keeping tabs on the 42" vs. 50" changing black issue. So far it seems 42" is much more vulnerable.
post #443 of 449
Quote:
Originally Posted by Kevin C Brown
6500K is usually the warm setting. This is from the calibrations given in mags that properly calibrate their displays like HT mag, S&V, TPV, WSR, etc. Additionally, when I first got my Tosh 32" HDTV capable CRT, I asked Toshiba directly what setting to use to get closest to 6500K. They said warm.
Interesting...I'll try out the warm setting tonight and see if that reduces the appearance of black-level shift at all. I don't have high hopes, but it's always nice to have an excuse to play with the plasma. :)

Somewhat off-topic: For those of you in-the-know, can you describe the "temperature" concept? I notice my LCD monitor gives me the options of 6500K, 9500K or custom. Not sure what this actually means.

Thanks,
Derek
post #444 of 449
Quote:
Originally Posted by Kevin C Brown
...a lot of people who've looked at or owned the 50" say that it doesn't have this ... feature. :)
Can these 50PHD8UK owners try Charlie and the Chocolate Factory. The blacks floats the whole movie. VERY ANNOYING. :mad:

After watching many movies without problems this is the first time I see the blacks changing quite noticeable during a scene. On Pirates of The Carribean the blacks lose detail when changing between certain scenes but It happens instantly - I can't see the blacks getting brighter/dimmer.



.
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post #445 of 449
Even Cnet noted this issue in their "review" of the Panasonic.
post #446 of 449
Yup. If you do a search, big long thread about that . Although I think "restoration" is spelled wrong in the thread title. :)
post #447 of 449
Quote:
Originally Posted by BruZZi
Can these 50PHD8UK owners try Charlie and the Chocolate Factory. The blacks floats the whole movie. VERY ANNOYING. :mad:

After watching many movies without problems this is the first time I see the blacks changing quite noticeable during a scene. On Pirates of The Carribean the blacks lose detail when changing between certain scenes but It happens instantly - I can't see the blacks getting brighter/dimmer.
I have not seen the black level changing on Pirates this on my 65. I don't think I can bring myself to get Charlie :)

-- Rich
post #448 of 449
To those of you with a 42PHD7UY who were wondering if the "black level fix" described elsewhere on this forum for the 42PHD8UK would do the trick for us, the answer is. . .

NOPE.

Last night, armed with the instructions from the FAQ, I went in to the Service Menu as directed, but there is no "letterbox" option to change (it apparaently appears below the remote control option on the new 8UK sets, but there is nothing there in the 42PHD7UY).

Oh well.
post #449 of 449
Quote:
Originally Posted by rmaier
To those of you with a 42PHD7UY who were wondering if the "black level fix" described elsewhere on this forum for the 42PHD8UK would do the trick for us, the answer is. . .

NOPE.

Last night, armed with the instructions from the FAQ, I went in to the Service Menu as directed, but there is no "letterbox" option to change (it apparaently appears below the remote control option on the new 8UK sets, but there is nothing there in the 42PHD7UY).

Oh well.
Those who are interested in the previous workaround, send a PM.
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