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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, 27 December 2011
Les Nicol

8:49 AM

Mike - You should be able to connect OK as the Viewsonic has a DVI port. Your "Freeview" chosen receiver would need to have an HDMI out and you would also need a compatible HDMI?DVI Lead to connect both. Picture refresh rate may not be as good as a dedicated TV but should be acceptable. "Cabling4less" are excellent for a balance of Quality and Budget.

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Les Nicol's 991 posts GB flag
Les Nicol

8:52 AM

P>> You would also need a suitable audio lead making sure ports are there on both LCD and "Freeview" receiver to connect to.

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Les Nicol's 991 posts GB flag
Dave Lindsay

9:49 AM

mike: I have a Viewsonic VX912 and it has in-built speakers. I know that many of these models don't have speakers in.

If yours has speakers in (and you wish to utilise them), then you need a lead with a 3.5mm stereo jack on one end and phono plugs on the other. The phonos go into the Freeview box and the jack plugs in to the monitor.

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Dave Lindsay's 5,724 posts GB flag
Saturday, 31 December 2011
Alan Nicholson
10:34 AM

I have recently purchased a Panasonic DMR BWT700 DVD recorder which is coupled to my Samsung tv via HDMI cable.

I also have a standard definition Virgin Media set top box, this is connected to the TV via Scart and to the dvd recorder's AV2 input also via Scart as stated in the dvd recorder's manual. However, although the picture is present there is no sound on av2. The recorder will record the AV2 picture well but still no sound.

The panasonic manual (which is not the best written manual) also states as a 'throwaway' that a 21 pin scart adaptor is needed. It states nothing about what type of adapator where it is connected etc.

Does anyone have any ideas about the lack of sound on AV2?

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Alan Nicholson's 2 posts GB flag
Dave Lindsay

4:44 PM

Alan Nicholson: I'm not familiar with these devices, but if I were you, I would remove the scart lead (from the VM box) that goes into AV2 of the DVD player and plug it directly into the TV.

If there is sound, then you know that sound is coming down the lead from the VM box. If there is no sound, then you know that the problem lies with the VM box not outputting it.

Another thought. I wonder what would happen if (as a test) you got rid of the HDMI cable and connected DVD player and TV with a scart (and put the lead from the VM box back into AV2). Can you hear the sound from the VM box with that setup?

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Dave Lindsay's 5,724 posts GB flag
Monday, 2 January 2012
Neil Bell

12:28 AM

Alan Nicholson I too have got a Panasonic DMR BWT700 Bluray Recorder and an SD Virgin Media STB and I just tried a short recording and the sound worked OK although it was intermittent on 1 channel at first due to a loose connection (I've got it wired through two switch boxes - just don't ask why! - but the final cable is a scart to AV2) I also tried (while recording) to use the BBC iplayer on the VM box and it (correctly) wouldn't let me record a copy protected programme but the BWT700 flagged this up so you'd know.

I'd double check the scart lead is fully home 1st and then try a different scart lead. The diagram in the BWT700 says you need a 21 pin scart lead and as you say it also says you need a 21 pin adaptor but I can't work out what is meant by that either.

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Neil Bell's 106 posts GB flag

11:58 AM

Neil Bell: Re: 21 pin adaptor, they only mention this when referring to the external device in case someone has a box or whatever not fitted with a normal scart socket facility but phono sockets etc, such as found in many devices of non UK origin.

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jb38's 7,179 posts GB flag
12:28 PM

i bought a Ross Freesat dish and reciever - DUB-S 5010, from B&Q in May 2011 (£25) set it up, and connected to our old TV via the SCART socket, we recieved upto 445 channels. For Xmas i bought a new HITACHI TV/DVD combo - L26DP04UE (HD, DVB,HDMI,Digital,Freeview) back of TV has 1 SCART, 1 VGA, 1 SPD/F, and a Coax-out. When i tried to connect it together, it says NO SIGNAL, i have tried most combinations and am now getting confused and annoyed

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kath's 6 posts GB flag
Dave Lindsay

12:52 PM

kath: The Hitachi L26DP04 receives Freeview (digital terrestrial television) for which you need to connect an aerial. Have you done this and if so, what is your location (preferrably post code) so that the likely chance of reception might be checked upon.

If you have it connected to the Freesat box using a Scart lead, then no tuning on the TV is necessary in order to watch the output of the Freesat box. Simply turn on the Freesat box (as you did with the other TV) and it should come on the screen. Should this not happen, then press the "Source" button on the remote (near to the top).

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Dave Lindsay's 5,724 posts GB flag
Saturday, 7 January 2012
9:52 PM

kath: thanks Dave,
postcode sk17 0be. connecting new TV to old aerial we get 10 TV channels and 21 radio.
attaching the Ross decoder box via the SCART produces - No input. have tried the 'source' on TV, SCART, etc still - No input. put it back on old TV and it works OK

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kath's 6 posts GB flag
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