Pansonic VT white balance shift - AVS Forum
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post #1 of 5 Old 05-16-2013, 08:10 AM - Thread Starter
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My VT30 has just gone past the 900 hrs mark and ive noticed today when calibrating it the WB appears to have shifted - previously the red had to be reduced significantly to achieve an even GS, however today and several profiles later with my i1pro the red only needs a slight adjustment. I checked this with both Calman 5 and HCFR and both programs reported the same. Also the black level as reduced, albeit slightly, but now getting around 0.0030 ftl as opposed 0.0040 ftl a couple of days ago.

Is this normal behaviour for a Panny?

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post #2 of 5 Old 05-16-2013, 10:54 AM
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Did you allow it to warm up with the meter on the device for the same amount time before each session? The meter, and display will have slight variation what was the difference in Delta E between the 2 session i.e. before you made your second adjustment of red?
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post #3 of 5 Old 05-16-2013, 11:10 AM - Thread Starter
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Originally Posted by airscapes View Post

Did you allow it to warm up with the meter on the device for the same amount time before each session? The meter, and display will have slight variation what was the difference in Delta E between the 2 session i.e. before you made your second adjustment of red?

Yep - used the same process as I always do - didnt measure the difference in dE however comparing the before and after, the red has gone from a gain of -10 to -4 to bring it in line. I did read somewhere that the colour temp of plasmas can change (with Panasonics) at approx 900 hours (C net), but this is quite a difference. Also the black level also improves upto approx 1500 hrs, apparently, which can explain the drop. I last fully calibrated at about 700 hours and have done a few checks this week. Set has 924hrs on it.

I have also resintalled windows 7 this week, installed net framework 4.5 and installed Calman 5 and the driver pack - wondering if there is anything else going on? Perhaps there was an issue before I reinstalled windows and didnt pick up on it. Checked the i1pro through the diagnostics and it passed. Will do a full calibration tomorrow.

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post #4 of 5 Old 05-17-2013, 11:30 AM
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It is well-documented that phosphor-based (crt and plasma) and projection lamp video displays drift over time. And the drift is not always in the same direction(s).

It is also well-documented that Panasonic slowly raises the black level of their plasma displays as hours are accumulated. Several years ago there was quite a dust-up about it because Panasonic was not changing the black level very often and when they did, the jump was large enough to be fairly obvious. That annoyed a lot of owners, so rather than figure out a way to not have to raise the black level over time (citing technical/performance reasons), Panasonic changed to more frequent increases of black level in much smaller steps so it would not be so obvious... you still lose the deep blacks over time, but they sneak it up on you rather than make a big change all at once.

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post #5 of 5 Old 05-18-2013, 02:07 AM - Thread Starter
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Originally Posted by Doug Blackburn View Post

It is well-documented that phosphor-based (crt and plasma) and projection lamp video displays drift over time. And the drift is not always in the same direction(s).

It is also well-documented that Panasonic slowly raises the black level of their plasma displays as hours are accumulated. Several years ago there was quite a dust-up about it because Panasonic was not changing the black level very often and when they did, the jump was large enough to be fairly obvious. That annoyed a lot of owners, so rather than figure out a way to not have to raise the black level over time (citing technical/performance reasons), Panasonic changed to more frequent increases of black level in much smaller steps so it would not be so obvious... you still lose the deep blacks over time, but they sneak it up on you rather than make a big change all at once.

Morning Dou.

Did a full cal yesterday with a new metre profile taken on Thursday night. The shift in grayscale was not apparent as previous tests showed on Thursday so something must have impacted the ability to take correct readings.
Anyways the drop in black level is still apparent, reading .0031 - .0034 however my understanding is that this will increase once it hits about 1200 - 1500 hours.

Cheers as always for your input.

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