Hello,
I have a proview MH462SU plasma which seems to have too much
red in the higher IRE at the factory warm color temperature setting.

I plotted the intensity versus IRE curve for all 3 colors and indeed red is a bit
too much starting from 50 IRE and higher.

My plasma has a user color temperatue setting with the RGB drive controls.

So I reduced the red drive and again plotted the intensity chart. Nothing
happened to the red intensity versus IRE curve. It sill shows higher red in
the upper IRE's

I thought the curve would shift downward towards the hopefully ideal 2.2
gamma curve which I also plot on the graph.

How do I resolve this? How do you determine if this a red color decoder
issue or grayscale tracking issue or the set's gamma tracking issue?

Is it possible to get rid of this excess red with just the RGB drive controls?

I do not have access to the service menu, if anyone knows I'd appreciate
if you could share.

Thanks

Sounds like color decoder to me.

If you adjust the grayscale correctly and remove any red errors there may be, the decoder is still going to feed your panel too much red. Grayscale tracking is for your blacks and whites only(and all grays inbetween) .

I suggest finding out how to enter the servicemenu and see if there are controls for color decoding.

Dimitri

Thanks dim65000,
I just checked the color decoder accuracy using the
avia color decoder check and indeed red is higher by about 10-15%.

But then why would the red push show up in the ire versus intensity plot for
the red primary I am attaching below?

The black curve is for the recomended 2.2 gamma

Reducing the red gain did not move the curve down as I would expect so I am
thinking it could be a gamma tracking issue.

I am thinking of putting a attenuator in the red signal and then trying again.
That would reduce red saturation but will it correct the red grayscale error in
the higher IRE?

The green and blue curves line up pretty well with the gamma 2.2 curve, I have not included these in the attached plot.

You'd have to trie for yourself, I pretty new to this game and I've had some struggles with gamma myself. I've got a pioneer plasma, and I always end up at 2.0/2.1 gamma. While 2.5 is best.

Couldn't it be contrast set to high?, and color shifting occurring?

Dimitri

Are you measuring a red pattern, or a grey pattern. This is enormously important. You need to be measuring a grey pattern when working on greyscale. Otherwise you add in color decoding problems if you're looking at red which is a different kind of signal.

Hi ChrisWiggles,

Yes, I am measuring the intensity of the various avia ire windows from 0 to 100 IRE.
I put the various avia filters (red, blue and green) to measure the intensity of the
primaries.

As I mentioned the green and blue track pretty close to the gamma 2.2 curve but
as seen in the plot red measures higher in the higher IRE's