1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Panasonic colour

Discussion in 'TVs' started by IvanFraser, Apr 10, 2004.

Tags:
  1. IvanFraser

    IvanFraser
    Standard Member

    Joined:
    Nov 12, 2003
    Messages:
    25
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Location:
    North Shields
    Ratings:
    +0
    I don't know if this has been mentioned before, but I noticed that my Panasonic TX-36PL30 has a strange colour configuration.

    I set about using DVE disc to calibrate and discovered that I could get red and blue set fine in the service menu. But green was way off.

    I turned it way down and found that it left yellow.

    This means that presumable the tv isn't provessing colours by RGB, but has a base level yellow that is adjusted by the red to make green, and if you alter red you alter green and if you alter green you're messing the blue and red.

    This makes it very frustrating when altering the colours, as they all seem to be affecting each other far too much. When the whites look pink, for example, I boosted the green or reduced the red - doing either shifted the dominance of the other colour to the point where only 1 notch either way left a predominance of the other - most noticeable on B&W pictures. (I'm working on reds and greens only and leaving blue alone as a base level, which is recommended by DVE).

    Try as I might, I can't get the greens in synch with the good reds and blues on the DVE disc all at the same time without leaving the picture saturated in green. It doesn't help that the factory settings make the green a different hue altogether to the background filter in the DVE disc.

    I also don't understand what the service menu means when it says 'high' and 'low' for the 3 colours - thus making 6 variable adjustmnts available, two for each colour. (with 6 variables, no wonder it's such a nightmare - there must be thousands of combinations).

    Can anyone enlighten me as to what the difference is between the 'high' colours and 'low' ones?

    And any suggestions (apart from calling in the technician) as to how to find the ideal settings for greens, as I suspect that the factory settings were incorrectly set up (unless there's been a bit of over-compensation going on at Panny's end to make the picture as acceptable as possible under the limitations of the crt).

    Cheers

    Ivan
     
  2. Zacabeb

    Zacabeb
    Active Member

    Joined:
    Jan 17, 2002
    Messages:
    474
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Ratings:
    +9
    First of all, what type of connection are you using between your player and the TV? This could greatly affect the color reproduction of the test patterns.

    Note that the following may not be exactly accurate.

    I think the high and low settings are the filament and cutoff voltages respectively.

    As you may know, the way a picture tube works is to create a beam of electrons by releasing them from a heated filament in the gun, and accelerating them by attracting them to plates with increasing voltages and openings for the beam to pass through. Finally the electrons leave the gun and instead get attracted by the high voltage charge around the face and funnel of the tube.

    The intensity of the beam, and thereby its brightness, is adjusted by varying the voltage in one of the plates in the electron gun (called VG2), which distracts the electrons and makes them go there instead of continuing towards the screen. The voltage of VG2 is the cutoff voltage.

    Both the filament and cutoff voltages need to be set up correctly for the tube, and then tweaked from there to produce the desired color temperature. If the filament voltages are too high, the filaments will wear out quick and the tube won't last as long. It's how high the cutoff voltage is when the picture is at its brightest and darkest that is affected when you adjust brightness and contrast.

    The separate low and high settings are needed to scale the cutoff voltage range for each color so that they are matched across the whole range from dark to bright.
     
  3. IvanFraser

    IvanFraser
    Standard Member

    Joined:
    Nov 12, 2003
    Messages:
    25
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Location:
    North Shields
    Ratings:
    +0
    Thanks for that info.

    So would you say it's best to raise and lower the highs an lows in equal increments and tend to prefer to lower the ones with greater intensity, rather than say raising blues to offset red saturation?

    I notice that when I take low red down to the most comfortable level, there is slightly too much green. If I take it down another 2 notches, suddenly the picture's red makes a big leap back up to oversaturation, whereas lowering the high red can just go down and down with consequent incremental loss of red (and increase in overall green).

    Thanks again

    Ivan
     
  4. Zacabeb

    Zacabeb
    Active Member

    Joined:
    Jan 17, 2002
    Messages:
    474
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Ratings:
    +9
    I'm not sure what would be best - myself I haven't bothered setting up the color temperature on my own set (a Philips - although it surely needs to be calibrated too). But the high and low settings probably interact a bit, so I assume it's normal they need tweaking to get the colors to match each other across the range. I wouldn't be surprised if the steps are too coarse to get it spot-on though...

    I am pretty sure the high and low settings are not proportional to each other either, so dropping both the high and low levels by say, 2 notches, won't necessarily mean the dynamic range between bright and dark stays the same.

    So, I hope someone with greater experience may answer what's the best way to adjust it on that set.
     
  5. IvanFraser

    IvanFraser
    Standard Member

    Joined:
    Nov 12, 2003
    Messages:
    25
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Location:
    North Shields
    Ratings:
    +0
    Thanks for that.

    I should imagine that it may help others with their sets as I know that Panny's have common issues and there's been stuff on here before re green 'push'.

    The most surprising thing for me though was finding that adjusting reds and blues, actually did just that - made them different intensities of the colour - whereas adjusting the green setting actually changed the hue of the green on the test pattern from yellow to deep green.

    This could also give a clue as to why so many people have issues using rgb inputs on Pannys - presumably they don't adhere to rgb processing and have to be further processed.

    My Sony Wega in rgb set the colour and couldn't be adjusted - only brightness could be tweaked in the normal menu; whereas in the Panny you can raise and lower the colour and sharpness in the normal menu in rgb mode.

    We'll see what others may have to say.

    Cheers

    Ivan
     

Share This Page

Loading...