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Connecting TV 10-12m from PC.  Which cable?

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Last Modified: 2013-11-08
I've got the job of setting up an LCD or plasma screen in a doctor's waiting room.  

The screen will be connected to a PC to display educational videos, custom Powerpoint/Flash presentations, play DVDs etc all coming from a PC with some kind of TV-out connection.

My question is *what* kind of TV-out connection?  The LCD/plasma screen will be 10-12 metres from the PC and the cables need to be laid below the floor this week.  What kind of cable can I run that will not pick up interference along the way?  I've not bought the TV yet (it will be coming from www.johnlewis.com - we are in the UK), nor have I bought any kind of card for the PC with TV-out yet so I'm completely in your hands.

For sound I presume there's no choice - 3.5mm jack from the soundcard to the red/white "phono" connectors at the TV end.  For the video?  Can a PC have a SCART socket?  Can a SCART lead be that long?  The yellow 'photo' cable, S-video, co-axial aerial cable? Help!
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For a full breakdown of scart connections and the scart standard try http://en.wikipedia.org/wiki/SCART

In the UK you should be able to buy scart to other format adaptors from Maplins or similar store - http://www.maplin.co.uk/free_uk_delivery/SCART_Adaptor_-9471/SCART_Adaptor_-9471.htm

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Buying a video card with video output is no problem - the cost of a card is pretty insignificant laid against the cost of a screen.

Audio via USB - not heard of that before - will USB be happy over 10m?  Once the cables go down and the carpet is laid there's no going back, so assuming the cable outlives the screen I'd be nervous about using USB in case it's a standard that doesn't stick around for TVs and a replacement screen in 5 years might not support it.

DVI for the video would be perfect - I know from using regular desktop monitors that a DVI cable gives a much sharper picture than VGA cables but Wikipedia says (http://en.wikipedia.org/wiki/DVI#Technical_discussion) that DVI is not happy over 4.6 metres without a booster but there is no room for any equipment en-route.

10m scart cables look commonplace but Wikipedia at DeeEmm's link says it carries only VGA quality, not that of RGB individual cables.  My instinct is that RGB cables between the PC and TV will work best, so I need to find a video card with RGB outputs and a TV with RGB inputs, and stick to 3.5mm/phono cable for the sound.  Is it safe to assume that will work?
Gary CaseRetired
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Gary CaseRetired
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... added note:   Here's an example of a video card with a DVI output (I know you can't buy from Newegg):  http://www.newegg.com/Product/Product.aspx?Item=N82E16814127301

Note that any card with an HDMI output will have to be connected internally to a digital sound (SPDIF) header ==> so you'll need to have a motherboard or sound card that supports this [almost all current boards do].

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Commented:
Woo, DVI can be connected to HDMI ports on TVs, that's good news - I didn't realise that - thanks for that.

Disappointing news is that I went to John Lewis today (very well respected department store in the UK, esp London) and their 5th floor is exclusively computers and TVs but they couldn't suggest a connection method and when I suggested DVI they told me I'd need a Mac laptop.  Doh.

Best they could suggest was a VGA cable - I was surprised to see how many (nearly all) TVs have VGA connections now.  Not really too keen on that - I know how poor a VGA signal from my PC is when compared to the DVI one... and that's only over a couple of feet.  They agreed to let me return with a 10m VGA cable and my laptop to see the quality on their instore plasma screens - so I will find a UK source for DVI/HDMI bits and go do that.

Apologies in advance if the question goes stale for a couple of days - I first need to get the bits together and probably ought to have someone from the surgery to be there for the test.
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Yes, DVI can easily be connected to an HDMI port ==> I have a 60" Sony HDTV that looks very good with the Windows desktop that is connected that way.   Note that the Sony manual says NOT to connect a PC to the HDMI input ... others may say that as well;  but that's only so they don't have to provide support for folks trying to figure out why their desktops don't fit :-)

A VGA input may look okay as well ... depending on how the TV processes it.   On the Sony, for example, it looks fine BUT it does not fill the screen (large black border completely around the screen).   Some TV's will allow screen-filling resolutions via VGA; so it just depends.   I think in general if you're buying a 720p set you can fill the screen via VGA; but with a 1080p set you probably can't (due to the lower bandwidth of VGA).

I'm not surprised that a department store sales staff isn't fully knowledgeable about this;  that's not where you'd likely find any real "techies" :-)

... and don't forget what I noted earlier r.e. plasma vs. LCD flat panels.   A plasma will work; and will look great -> but does have potential image burn-in issues ... which is why I don't recommend them for a computer display.

Author

Commented:
Cheers folks.  In the end we ran some network cable to a corner by the TV and installed a tiny new PC about 4 ft away from the TV.  The installers looked at the DVI with sound added to it for an HDMI connector but the tiny PC's internal (and silent) graphics card didn't support DVI, so we bailed out and went for a VGA connection - not too bad over such a reduced distance.

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