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Connecting it all up

Why are there so many sorts of connecting cables? Find out with this quick guide.

Why are there so many sorts of connecting cables?  Find out wit
published on UK Free TV

Why are there so many sorts of connecting cables? Find out with this quick guide.

The connectors on each cable are called plugs (and are also called male) and they will usually fit only into one sort of socket (or female connector).

Most cables you will come across are male to male. Occasionally you will find leads with a socket on one end and a plug on the other, and these are called "extension cables".


The SCART cable is used to connect a set-top box to a television set, or to a video recorder. This can only be a short cable. The SCART cable carries all of these types of signal:

  • analogue stereo sound
  • a single RGB television picture
  • a single composite video picture
  • a single S-Video video picture
  • widescreen picture signal

As stereo sound, RGB picture and widescreen signal is the best possible combination for digital television viewing, it is vital to use a SCART lead between any set-top box and the main television.

The composite video picture with stereo sound is the best combination for a VHS video recorder. If your set-top box has two SCART sockets, it is likely that the one marked TV will carry RGB picture information and the other will not.

If your television has more than one SCART input, you may need to choose a special one (marked RGB) if you want to use RGB from the SCART cable.

On most set-top boxes it is possible to turn the RGB output on and off. This can be used to test the RGB input function on the television ? the picture quality appears blurred when it is disabled.

If have a DVD player, rather than a VHS recorder, you can attach this to the set-top boxes second SCART connector. The signal from the set-top box will normally be overridden by the DVD player when it is on, usually in high-quality RGB.

Some very cheap SCART cables do not have all the pins connected. They may not provide RGB and widescreen picture signals. SCART cables are normally no more than three metres in length.

UHF lead

The UHF lead is a lead that you would traditionally associate with television signals. They can carry:

  • up to 45 (but normally only five) analogue television channels
  • a single picture from a set-top box
  • around 50 analogue cable TV channels
  • mono sound
  • NICAM stereo sound
  • Teletext services (for example, Ceefax)

You can't avoid these cables if you are going to use Freeview, as these cables are the only ones that you can use to distribute Freeview signals around the house.

Where you have an integrated digital television (an idTV) you just need to get the signal from the aerial to the television with one of these cables.

If you are using a Freeview set-top box, you will need to get the signal from the aerial to the set-top box using this aerial lead, but for best results connect the TV to the box with a SCART cable.

You can also use a UHF lead to connect a set-top box to a television somewhere in the house. Your set-top box will require a RF (radio frequency) modulator. Note that "RF passthough" is another way of saying there is no modulator. You will be able to "tune" the second television into the picture showing on the set-top box.

Some boxes (all Sky boxes) have the ability to connect a remote control receiver to the second TV end of the interconnecting cable, so you can change channels.

The set-top boxes, whilst providing a reasonable quality picture to the second TV, will always provide only mono sound via a UHF lead.

The step-change in picture quality obtained by switching to RGB on a SCART is far greater than any obtained though spending any more on a gold-plated SCART cable.

Satellite or cable TV cable

These cables are usually very stiff, and have a very basic screw connector on the end. Usually they will provide an unbroken link to the satellite dish. At the dish end they plug into the device on the end of the arm, the LNB.

Don't try to disconnect these cables when the set-top box is on. Usually there is a small voltage that will cause dangerous sparks.

If the cable connects to a satellite dish, there is not much you can do with the cable. Each receiver in the set-top box needs it's own wire to the LNB. With a personal video recorder (such as Sky+), or a multi-room installations there are two cables to the four-output LNB on the dish. If you want more rooms, each will require it's own cable.

If the cable is providing cable TV, then it is possible to use inexpensive "Y connectors" to link the incoming signal to various set-top boxes, cable modems, or - via an adaptor - directly to the back of a TV.

Composite video cable

This is the most simple and basic video connection you can get. It carries:

  • a single picture from a set-top box

The picture will be in colour, and of comparable quality to a analogue broadcast station. However, there is no sound. For that reason this cable is often found joined to a stereo audio cable.

These signals are quite robust and can be carried for many metres. Often modern television sets have a single yellow photo input on their front input panel.

You also use an identical cable to carry digital stereo (SPDIF) sound.

Stereo audio cable

These cables carry the left and right channels of sound on two joined cables. They are usually required when a SCART cable is not being used, as the SCART cable already carries stereo sound.

If you are connecting your set-top box to an external stereo system, a separate stereo audio is used.

There is no real practicable limit to the length of these cables, but excessive length will degrade the quality of the signal.

S-video cable

The S-video standard is not well supported by most UK digital TV boxes, and very few have a S-video socket. If you need one for a particular analogue camcorder, use it, but avoid S-video with digital television. If you are using what appears to be a monochrome picture from a SCART lead, it will certainly by an incomplete S-Video signal and you should change to the RGB input.

VGA cable

This is the cable you will use to connect a computer to a old style monitor, and some modern LCD screen too. Most modern LCD TVs will have a VGA input too.

If you want to connect a set-top box to a LCD monitor, you can buy a conversion box from around 60. However this will not result in a better picture than using an existing SCART socket if there is one.

The only way to get higher than normal television resolution is to use a VGA in conjunction with a personal computer or modern games console.

DVI cable

If you want to get the very best out of a television or monitor use a digital video interconnect (DVI) cable.

This will be the only way for most televisions and monitors to receive high-definition pictures from a computer, and some set-top boxes.

If you can use either a VGA cable or a DVI cable, choose the DVI option.

HDMI cable

If you want to get the very best out of a television use a HDMI cable.

This will be the only way for most televisions to receive high-definition pictures from set-top boxes.

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Thursday, 16 June 2011
tom munro
8:54 PM

Hi, I am a senior, I have virgin cable box {vcr with analogue tuner music center, sony recorder, tv.
We have been switched to dg 15th june, previously I was getting all freeview programs, but now only one group, would the music center {analogue tuner} be stopping other freeview chanels , or is there another solution to receive all channels as before switch over.
I can get all chanels if I plug ariel direct to tv so it appears a loop poblem can you advise, thank you.tom.

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tom munro's 2 posts GB flag
Friday, 17 June 2011
3:09 PM

Hi, Alice here again. I have now connected my DVD recorder to the TV using an HDMI cable, and connected the V+ box with an HDMI cable to the TV. I then connected via Scart, the V+ box to the DVD recorder. I bought a new RF ariel lead which has solved the picture quality problem.

I have set up the V+ box to be in HD which is great.

However, I am wondering now how to record V+ HD onto DVD. The DVD will not record the HD broadcast on the TV setting. It will record what I'm watching on V+ via the AV2 channel on the DVD. BUT... not in HD quality.

Is there any way around this?

Am I able to record HD V+ in HD using my HD-ready DVD recorder?? I guess not as it's connected via Scart... but I just wondered if there's any way the DVD can pick up the HD signal via the TV, as the picture quality appears great on normal TV, but poor in comparison via the DVD AV channel.

I hope someone can help!!

Thank you so much.


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Alice's 5 posts GB flag

3:47 PM

Alice: You havent mentioned what model of Samsung DVD recorder you are referring to, (R135?) but it should be pointed out that just because it has an HDMI socket doesnt mean it can actually record in HD, as the HDMI socket is only an output to enable up-scaling of a normal recording, and not for for the input of an HD signal.

Maybe you could confirm (or not) the model number.

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jb38's 7,179 posts GB flag

4:24 PM

tom munro: If you can get all channels with the aerial plugged directly into the TV, then that means that doing it via the music centre or whatever is reducing the signal level to below what the TV can operate on.

The analogue tuner will not have any effect as far as the problem you mentioned is concerned.

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jb38's 7,179 posts GB flag
Saturday, 18 June 2011
wallace douglas
10:44 AM

hi folks im wallace. im having trouble linking standard sky, free view through a booster and then distributing the signals to other happy putting sky on down stairs and watching it upstairs but iv no sound is there any sites you are aware of posting wiring maps

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wallace douglas's 2 posts GB flag
wallace douglas
10:56 AM

i have taken dish and antenna into sky box.
then out of sky box into booster and out of booster to freeview boxes to the tvs. i gather this is wrong

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wallace douglas's 2 posts GB flag

12:09 PM

wallace douglas: You really have to first of all make sure that coupling the co-ax connectors together (normally fitted into the Sky box) actual does gives good reception in the other rooms before linking them through the Sky box.

If they do, but not when the Sky box is added, then that can indicate that the Sky boxes RF output channel chosen for feeding the other rooms is clashing with the channels being received.

You havent mentioned your location so advice cannot be given on a suitable channel to use.

Remember of course that the Sky boxes RF output is analogue and not digital, so the TV's in other rooms will have to be set on an analogue scan to receive the Sky box.

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jb38's 7,179 posts GB flag
Sunday, 19 June 2011
11:14 PM

Hi JB38. Thanks for your comment. The model number is DRT389H.

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Alice's 5 posts GB flag
Monday, 20 June 2011

7:24 AM

Alice: Thanks for the info, and which unfortunately confirms what I suspected, insomuch that the HDMI socket is purely an output for up-scaling purposes of normal DVD's etc, as the device itself is not an HD capable one.

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jb38's 7,179 posts GB flag
Mike Dimmick

1:33 PM

Wallace Douglas: If you have picture, but no sound, you probably have the TV set to the wrong mode. You need to make sure it is set to PAL I, System I or UK, not B/G or any other option that might be available.

I'm assuming that the satellite receiver is an official Sky box and not some other free-to-air receiver. If it isn't a Sky box, check that the receiver is also set to PAL I or UK. If it's a plug-in modulator, note that some sold by came pre-set for PAL B/G and need to be adjusted for PAL I.

TV transmissions have differed somewhat around the world, with the sound carriers at different locations relative to the video information, and sometimes different ways of encoding the sound.

If you're interested, there's a list of how the picture and sound were transmitted at World Analogue Television Standards and Waveforms .

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Mike Dimmick's 2,486 posts GB flag
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