OT: TV Repair??

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On Thu, 05 Jun 2008 23:54:26 +0100, Harry Bloomfield wrote:

Fed from an analogue source derived before any transmission MPEG crap can get at the signal?
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Dave.




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laid this down on his screen :

It's just a shame that CRT sets knock spots off of both technologies, and always will ...
Arfa
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laid this down on his screen :

Up until recently I would have agreed with you 100% - but digital technology is advancing so fast that there are a few, and I admit just a few, flat panel sets that are now as good as the best CRTs.
Up until switching to the Panasonic plasma I had a Philips pixel plus CRT - always highly regarded and well reviewed with comments such as "The closest you'll get to HD with a standard set." But there are drawbacks with CRT technology - not least the difficulty in maintaining accurate convergence across the entire screen. This means that on even the best CRT tv's there is invariably colour fringing around white objects (particulary text) at the outer edges of the screen. This usually becomes even more obvious the larger the screen.
My son still uses a Philips pixel plus set and so I have the opportunity to regularly compare the picture quality on my Panasonic plasma set with his crt set. I can say with confidence that the picture quality on my Panasonic is superior in almost every way bar one - the occasional 'staggering' of diagonal lines on my set (which is really only visible and noticeable from close up). Of course, when receiving a HD signal from my Sky HD box there is no comparison at all - the plasma screen wins hands down!
DIY
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They don't. If they did why has almost everyone switched to lcd for computers? It depends on the source driving them.
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wrote:

They can, but, like most things these days, they tend to be made down to a price rather than up to any particular quality level.

Power consumption, desk space, cost...

And on the quality of the tube or LCD panel being used to display said source.
MBQ
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Exactly right. Although there are extremely good lcd and plasma sets out there that match, if not exceed, the picture quality of the best crt TVs, there is still a lot of dross. To get a good quality picture on a flat panel TV you have to spend money on a top brand such as Panasonic, Sony, LG, etc. These are the firms that spend the most on research and top quality components.
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Would that that were true ... All flat screens, no matter whether LCD or plasma, and no matter what they cost, or who makes them, suffer from motion artifacts, due to lag in the panel, and digital processing times. These effects are exacerbated by the speed of the motion, and when the set is working in a non-native resolution i.e. at 'standard' transmission resolution, rather than HD.
There *are* flat screens where these issues have been addressed, and which are very much better than others, and that is a cost issue but, seeing these things all the time in the course of my daily work, IMHO they still can't hold a candle to even a cheap-priced CRT set working on a good signal, and for that reason alone, I won't be trading my large-screen CRT Tosh for a flatscreen, anytime soon. :-)
Arfa
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Arfa Daily wrote:

Actually all SCREENS.
Phopshor persistience..speed of scan,. is nothing perfect?

Same goes for CRT of course.
Digital TV is far far worse than analogue TV, than LCD is to CRT.

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Speed of scan and phosphor persistence are optimised to minimise flicker and to use a sensible bandwidth for the transmission, whilst not, in themselves, producing significant motion blur ...

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Of course it depends on the CRT quality too. Some don't have enough DPI - some have the wrong phosphors.
Before I bought my DLP rear projector I was intending buying a Loewe due to having seen one at a friend's and being impressed. It was a 32" widescreen CRT. I wanted a larger one and intended getting their 36" model - but it was nothing like as sharp, and had poorer reds, which effected the flesh tones badly. I've a feeling they'd bought in the tube from a different maker to the smaller one.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Are you suggesting that modern crt TVs don't use digital processing? Of course they do - with the resultant side effects of artifacts etc.
Everyone to their own of course - but I *am* someone who has always been very fussy about picture quality (I can remember driving TV engineers mad with my insistence that they spend much time with a cross-hatch generator while they adjusted the convergence until it was as near perfect as possible! (that was in the days when you could adjust convergence of course!)).
I put off buying a flat panel set for the very reasons you outline - but things *have* improved - and I am extremely satisfied with my 37" plasma (that I have spent some time with - setting the picture up just right). I can't vouch for it's picture quality on analogue signals - because I never watch anything other than via Sky or the built-in Freeview but with good quality digital signals the picture is excellent - and with HD it's superb. I often find myself watching HD programmes that I wouldn't normally watch simply to revel in the picture quality!
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<snip>

Of course I'm not, but there is no requirement for the set, when operating in normal resolution, with a standard signal going in, to process that signal to make it fit the resolution of a panel device that has individual and digitally switched, picture display elements - that's LCD or plasma 'cells'. In order for this to take place, the signal has to be written into memory at one rate, and clocked out at another, with the resultant requirement of dropped or duplicated pixels to get that 'fit'. That's all very well, until something is moving fast across the screen - that's a football or a racing car, for instance. In this case, the electronics have a job 'keeping up' with the translation process, to say nothing of the decoding delay when the incoming signal is digital. A further consequence is that 'interference patterns' are generated within the translation algorithm, which manifest on the screen as motion atrifacts. These artifacts are not apparent on CRT sets, which do not have the requirement to have the translation done. That said, I have noticed recently, that as all outside broadcasts go digital, motion artifacts from the programme originators are creeping in. A good example was this year's World Snooker Championship. Slow motion replays, and freeze-frames, were covered in digital artifacts, which had not been apparent previous years.

"improved" - key word, I suggest ...

I don't dispute that a good quality plasma, as you say, 'properly' set up (Pioneer offer a super set-up option through their dealers, where a specially trained engineer visits you to spend the time that is impractical in the factory for cost reasons, to set up your set to perfection) is very acceptable, particularly at a 'sensible' viewing distance, but with the best will in the world, they are still not, in my opinion, as good overall at displaying *any* and *all* picture content as a decently functioning CRT set. They are a fashion compromise, striving to be as good as the mature technology of CRTs, but at nothing like as good a price.
I never touch the brightness and contrast settings on my CRT Tosh, from top quality studio video sources such as the news, through films to some low bit-rate satellite transmissions, but when I am working on flat panel sets, I find myself wanting to adjust them all the time depending on picture content, and I wince at the motion blur and display artifacts that appear under *some* circumstances ...
Arfa
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Fashion and the fact they're smaller, lighter and cheaper to make. Have you ever tried lifting a decent 21" CRT computer monitor?

Computer derived signals ain't the same as broadcast ones. Oh - and 99.9% of the time the only high quality stuff you're looking at on a computer is still frames.
A pal who is a graphic designer refuses to get rid of his CRT monitor. And cost doesn't come into it.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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wrote:

They are with digital.

That is because he is caught up in a myth. The myth is that CRTs display more colours and better black levels so display the images better. Which to some extent is true. However the image is then displayed on an LCD or, worse, printed. Then it doesn't matter at all if the graphic artist used better kit. In fact he may have produced better results using the target display.
Its quite a common belief that you have to have the best to do professional work, which is obviously untrue. You have to have better/same than the intended audience.
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Eh?
No he's not. He's a very picky professional.

Neither of these is a myth.

Then why call it a myth?

Not worse. Being a pro he knows what fiddle factors are needed for printing.

That is a myth. You might as well say broadcast should use domestic cameras and cheap microphones etc as the 'target' audience won't know the difference. And I've seen it tried by bean counters with disastrous results. The correct way is to originate the highest quality and let the end user degrade it if that's what they want.

Are you a bean counter in another life?
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Yes well ... the broadcaster does quite well degrading it for final delivery both Sound Radio and Vision;-!...

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Tony Sayer




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London SW

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Who said he refuses to use one?
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*The statement below is true.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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dennis@home explained on 05/06/2008 :

I never found CRT's very satisfactory in a really dark room. The dark scenes being swamped by the minimum black. I was amazed by the black level of plasma when we first got ours.
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Regards,
Harry (M1BYT) (L)
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That simply doesn't make sense. The pictures from the cameras are adjusted on CRT monitors and that includes the dark tones. If you're losing detail there your set is not adjusted correctly.

Amazed by the lack of it, presumably?
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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