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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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Tuesday, 23 October 2012
9:25 AM

I have a samsung tv model ps42c450 and a sky+
box I want to connect my DVD recorder to this so that it all works but have not been able too, my tv has only one scart socket help please

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Derek's 4 posts GB flag

9:51 AM

Derek: You connect the SCART on the DVD recorder to the "VCR" SCART on the Sky+ box. The you put the Sky+ box into stand-by mode to access the DVD recorder.

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Briantist's 38,899 posts GB flag
Friday, 26 October 2012
Saturday, 27 October 2012

12:09 AM

Derek: What Briantist has said "is" the standard way of doing things, and when you said that it doesn't work then in what way? is it that even although you have put the Sky box in standby the DVD is still not coming through the TV? or are you meaning that Sky cannot be viewed at all when connected as advised as the DVD is locking out Sky? and which with "some" DVD devices can happen even when the item in question is in standby.

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jb38's 7,179 posts GB flag
Friday, 9 November 2012
1:19 PM

sorry jb38 have not been able to get to the computer. It is exactly as you have said in the first part of your answer. The DVD is not comingthrough to the TV.

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Derek's 4 posts GB flag
Derek's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage

11:13 PM

Derek: On the assumption that the DVD recorder has been verified as being OK by having been connected straight into the TV, could you please supply the brand / model number of the Sky box in question, and is it a Sky+ HD box or just Sky+?

The other point being that your Plasma TV appears to have only one scart socket, and so "if" your Sky box is and HD type connected via an HDMI lead into the TV's HDMI(1) input then the DVD recorder would require to use the TV's scart socket, this AV (ext) input being selected using the "source" button on your TV's remote control.

Further advice dependant on answers.

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jb38's 7,179 posts GB flag
Monday, 12 November 2012
1:24 PM

jb38 thanks for the info will have to give it all to you at the weekend when i am off. sorry have to run now and thanks again.

link to this comment
Derek's 4 posts GB flag
Derek's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
Saturday, 24 November 2012
Margaret Stoker
2:44 PM

I have just bought a Bush pvr and I already have a Panasonic duel vcr/dvd recorder my tv is a Tosiba with two scart sockets. I obviously now want to record to my pvr but still want to use my other machine even if only as a player for discs and tapes. I have set up the new pvr with the scart in the second scart socket of the tv as the tv manual states for a media recording machine and the two RF cables connected to it and the other recorder with its scart to the first socket on the tv. There is also a HDMI cable from the original recorder to the TV which I have not moved. Even if I put the RF cables back in the older machine I have no picture or sound just a blue screen then of course my pvr wouldn't work. The only way the older machine works is by being connected as it always was and no connection on the new PVR. HOPE SOMEONE CAN HELP IN VERY SIMPLE TERMS PLEASE

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Margaret Stoker's 1 post GB flag
Tuesday, 4 December 2012
10:09 PM

I have a new flat screen TV with an HDMI port and I want to connect to a SKY box with a SCART port. How do I do it.

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Pauline's 1 post GB flag

11:36 PM

Pauline: If your new TV is not fitted with a scart socket as well as the HDMI then could you please indicate the brand / model number of the TV in question, as although scart to HDMI adaptors (upscalers) are available they are all priced in the region of between £40 / £50 or so, and once the model number is known its technical details can be checked out as there may be a way around the problem.

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jb38's 7,179 posts GB flag
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