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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.

Help with Television sets?
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In this section
Loft aerials1
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Now and Next6

Tuesday, 17 May 2011

3:33 PM

mark: You can't attach a FreeVIEW box to a satellite dish, only a FreeSAT box.

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Briantist's 38,910 posts GB flag
Mike Dimmick

3:52 PM

Lisa: If it's just a computer monitor, rather than a TV, you would need a Freeview box that has an HDMI or DVI output, or a SCART-to-VGA cable.

Freeview HD boxes should have an HDMI output - you can convert from HDMI to DVI if the monitor has DVI input.

You would have to connect the audio through a different cable - check what the monitor requires, if it has built-in speakers, or you may have to provide a separate amplifier or speakers. You might need a dual phono (or RCA) to stereo 3.5mm jack adapter. Again, depends on the box and the monitor.

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Mike Dimmick's 2,486 posts GB flag
Wednesday, 18 May 2011
7:08 PM

I have a TV with DVI connection and Virgin HD Box with HDMI connection, I purchsed a HDMI to DVI lead which gave me no sound. I know I need to connect seperate audio leads but I have no audio connect on the Virgin Box. It has scart, HDMI, USB, SPDIF and Ethernet. I did read I could buy a converter to put in the scart socket which has audio outputs on it that I could connect to the TV, would this work?

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Tracy's 1 post GB flag
Mark Case
11:09 PM

I have bought a vision digi sender,so i can watch sky on the tv downstairs.i followed the instructions,a the picture is ok and u can change channel but the sound is poor its faint and crackly!can u help?

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Mark Case's 3 posts GB flag
Thursday, 19 May 2011
brian bettell
7:53 PM

hi going to purchase freesat hd and all items when connecting hdmi cable will i lose freeview using normal ariel

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brian bettell's 1 post GB flag

9:15 PM

brian bettell: There isn't really any connection between the two items mentioned as they are individual units operating with their own aerials, the Freesat from your dish and the Freeview from a normal aerial.

Likewise the HDMI lead from the Freesat connected into the HDMI socket on your TV, and with the Freeview connection to the TV usually being of the scart lead variety into the appropriate scart socket on your TV.

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jb38's 7,179 posts GB flag

10:35 PM

Tracy: Sometimes you can do this, it depends on the TV. You would probably be better off putting the sound though an external amplifier, but you need to check the TV manual.

SPDIF is the best quality (digital) sound you can get from the Virgin box.

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Briantist's 38,910 posts GB flag

10:38 PM

Mark Case: Check that the sound output levels on the Sky box are set "high".

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Briantist's 38,910 posts GB flag
Sunday, 22 May 2011
12:05 PM

I have just left Sky+HD after enduring 11 years of their near monopoly and have bought a Humax FOXSATHDR1TB. I have a Sky+ dish with Quad LNB but only 2 cables running to my lounge. I also have a co-ax distribution from my loft running to 3 bedrooms, lounge and kitchen. I would like to watch at least 2 different channels in different parts of the house. Do I need additional tuners and/or some kind of multiplexer/amplifier in my loft?

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Pete's 1 post GB flag
D Harvey
5:18 PM

I have a panasonic viera tv virgin v box and a panasonic dvd recorder can you show me the wireing connections please

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D Harvey's 1 post GB flag
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