picture quality issues with LCD TV

Discussion in 'Displays' started by JoshR, Dec 5, 2004.

  1. JoshR

    JoshR Agent

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    I have a specific situation I hope someone can help me with, but if not, general comments/insights about this issue are welcome, because it's an ongoing issue for me.

    Lemme explain: I'm a salesperson at a large electronics store. I work in the mail-order dept., which isn't near the products themselves, so I don't have easy access to the merchandise. That can make it difficult to troubleshoot issues if a customer calls with a problem, and that's what happened yesterday.

    I had sold him a Sharp 37" LCD TV, model LC-37GD4U. He received his TV and hooked it up to two video sources: an Onkyo DVCP702B DVD player, and his HDTV cable service. He called because he doesn't care for the picture quality using either signal, and he especially doesn't like the DVD picture. He complained of blurriness with both signals, and also "weird color" with the DVD. He's very dissatisfied in both cases.

    My guess is that he shouldn't be this dissatisfied. This is the first time I've ever received such a strong complaint about picture quality on any LCD or Plasma. So I'm trying to figure out what could be wrong, and all your suggestions would be appreciated.

    Here's all I can think of:

    1) DVDs can sometimes look funky on a hi-def display because they're being blown up to fit the higher resolution. The Samsung 841 and 941 units are supposed to help with this.

    2) Maybe he's not using the progressive option, or not using it correctly? Should this require any special doings with either the DVD player or the TV?

    3) He's using component cables from both sources. Should he try something else?

    Of course, I'm sure there's other possibilities I didn't think of. It just seems that this customer shouldn't be this upset with his picture quality, so there must be something we're both missing.
     
  2. Leo Kerr

    Leo Kerr Screenwriter

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    Well...

    Component should be the best choice in most situations (discounting DVI, HDMI, IEEE-1394 and all sorts of other non-standard options.)

    Obvious problem with component, especially with the DVD: did he get the three wires in the right spots? A possibility worth considering is reversing the color difference pair at one end.

    I'm not familiar with the menues on any of these units, but there may be (oh! oh! Just remembered one more ugly possibility) menu settings for setting the thing up.

    The thing I just remembered is that some of the ports may be menu selectable: RGB or YUV. Get them set wrong and you get... interesing results. (At least, that is, RGB into a YUV looks really funky.)

    I suppose another thing for over-the-phone troubleshooting is to see, 'how does it look with S-Video?' If the color gets corrected, for example, I'd be suspicious of a user setting or cable issue.

    The blurriness (is that right? It looks really bad.) is a more... interesting issue. I use interesting in a rather loose fashion, and would be very interested to hear what's really going on with this one.

    Anyone else?

    Leo Kerr
     
  3. Dean_S

    Dean_S Second Unit

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    My 37" Sharp came out of the box with the backlight turned all the way up. After calibration with Avia with setting ended being 1 mark below center (standard is center). I also found that using the DVI from my Zenith 520 STB helped an HD picture noticably but it was still totally acceptable using the component input. I've only watched 2 DVDs on this set being my secondary set and it's in my bedroom that currently has an incomplete home theater but again, progressive scan using component looks very good (Panasonic RP62). You need to find out if his HD STB has DVI and suggest trying that but I'll bet that most of his problem is calibration since mine looked pretty horrible right out of the box.
     
  4. JoshR

    JoshR Agent

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    Dean - Ok, I'll recommend calibration. I think we sell that Avia disc, actually.

    Leo - I don't think his Onkyo player has DVI outputs, but maybe that's all the more reason to suggest the Samsung 841 or 941. Still, I think you're right that component shouldn't look as bad as he says it does.

    I did ask if he had all the colors lined up, and he said he did...

    Can you elaborate on this RGB/YUV thing? This is one of those things I'm really confused about: are there different kinds of component inputs that LOOK the same, but only some are for HDTV? Does this mean he can't plug his component cable into any input with red/green/blue jacks?
     
  5. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    The Sharp has a ton of colour decoder parameters in the user menu ... that can mess a person up royally if they don't know what they are doing.

    AVIA might help ... but then again, the THX Optimizer on many discs would also help. Beats selling him a $50 disc and he uses it wrong and he gets even angrier ...

    DVI and COmponent should be fairly close ... and more expensive cables won't solve this either .



    Regards
     
  6. Leo Kerr

    Leo Kerr Screenwriter

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    There are basically two types of analog component video; one of which is the only one that should be called 'component.'

    The two basic types are
    1. Component (Also called YUV, Y-Pr-Pb, and probably some other names, but those are the big usages.)
    2. RGB, short for Red-Green-Blue.

    Component video is delivered over 3-5 connectors; typically video sync is carried on the Y channel, but in some cases, it may be a seperate 'composite sync' (4 connectors,) or component sync (5 connectors - horizontal is seperate from vertical.)

    RGB is also delivered on 3-5 connectors, RGsB, (sync on green), RGBS (composite sync) or RGBHV (component sync.)

    RGB carries the most fundmantal form of analog video; each signal is a complete 'channel' of information.

    YUV has the luminance 'detail' information on the Y (which is actually the Greek Lambda, I think,) and two support channels. By subtracting the U and V channels from Y in different combinations and keeping the different results, you can then derive the RGB to drive the picture. The advantage, if I might digress here, is that YUV occupies less bandwidth than RGB, and is, in theory, a lossless transformation. (It isn't, really, but it's generally close enough.)

    Two sorts of things can go wrong here. First, if you reverse the U and V channels, rather than subtracting the blue difference channel from the luminance channel to get part of the green and the blue, you're actually going to get the red channel mapped into the blue color space, royally hosing the color setup.

    The second thing is if you plug a YUV into a port that thinks it's getting RGB, or the other way around, then you're going to get interesting results - again.

    Now, think about this. On even really nice (read: big) high end / professional equipment, there's still only a finite amount of space. Why use ten BNC jacks when you could use five and a switch? I know the Panasonic plasmas that I encountered this with have a soft menu-based switch to select RGB vs YUV. (Found it the hard way.)

    And, by the by, often these jacks, if color coded, are the same. RGB will be marked with RGB - but so will YUV - just Y=G, Pr or U (I think)=R, and Pb or V (I think again)=B on the rings.

    The problem I still have with all of this is, why is the picture soft?

    Leo Kerr
     

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