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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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Friday, 17 February 2012
Dave Lindsay

12:41 PM

Mark Peterson: I cannot agree with your assertion that the Technisat technical helpline is not very helpful. I think that they were simply stating fact.

I have looked at the specification ( HDFV [0006/4940] - TechniSat Digital - en_XX ) for the model you refer to and it would appear that it only has one tuner in it. This means that you cannot watch one programme that is being broadcast whilst recording another using the in-built tuner. It will allow you to watch a recorded programme whilst recording another. So Technisat are quite correct.

However, this does not prohibit you from recording one channel using the Technisat box whilst watching another channel using the TV's in-built tuner. Simply feed the incoming aerial into the Technisat box and then connect its aerial output to the TV's aerial input.

If you still want the Sony HDD/DVD machine available for recording over the air programming, then you can daisy-chain its aerial connections as well.

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Dave Lindsay's 5,724 posts GB flag
Mark Petersen
2:27 PM

Thanks for the info, Dave.
I realise that if I use the set's PVR function to record to an external HDD I cannot record a different channel to the one I'm watching on TV. What I want is to be able to use the set top box to view HD freeview channels and to use the DVD recorder to record different non-HD chanels -would the daisy chain allow this. Any advice gratefully received.



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Mark Petersen's 4 posts GB flag
Saturday, 18 February 2012
Dave Lindsay

1:17 PM

Mark Peterson: Yes, you can do that. It shouldn't matter which you feed the aerial into first.

You must have the Technisat connected to the TV using a HDMI cable in order to view high definition programmes in high definition. Connect the Sony HDD/DVD to the TV using HDMI (if it is available) or scart.

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Dave Lindsay's 5,724 posts GB flag
Mark Petersen
4:55 PM

Bingo! Connected it all up and it works just how I want it. Thanks Dave Lindsay for your help.


Mark Petersen

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Mark Petersen's 4 posts GB flag
Dave Lindsay

5:18 PM

Mark Peterson: No problem; happy to help.

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Dave Lindsay's 5,724 posts GB flag
Tuesday, 21 February 2012
6:59 PM

Our TV just died after 5/6 years faithful service, and we are wondering the best way to get a new TV, the only problem is that we have a Virgin V+ box with Scart & HDMI leads, a DVD player with scart and a WII, and I am trying to find out if I have to have both of the V+ cables attached at the same time or if only 1 is needed? and how would I connect all 3 devices to a new TV if most of them only have 1 scart lead?

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Stuart's 2 posts GB flag

9:14 PM

Stuart: You only require to connect the Virgin+ box to the TV using the HDMI lead with this leaving the TV's scart socket for use with the DVD player, the problem might be with the Wii as I notice it does not have either but uses a multi plug with a connection lead for A/V / component / and "S" video output connections, so you will have to ensure that any TV you purchase has either of the "first two" input facilities mentioned, although scart adaptors with AV (phono) input sockets on the back of them are available from places like Poundland and similar, although if it was connected this way you would also require to purchase a "selectable" two way scart connection box, its common lead connected into the TV's single scart socket.

This said though assuming that you do have the special Wii connection leads? its the one with a multi plug on one end (for box) and coloured phono plugs (x3) on the other end for an AV connection into a TV.

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jb38's 7,179 posts GB flag

10:51 PM

Stuart: Just in addition to that said, the only reason I mentioned the scart adaptor is just in case by any chance the TV you purchase does not have phono plug AV inputs albeit it most likely will have.

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jb38's 7,179 posts GB flag
Wednesday, 22 February 2012
7:26 PM

Hi JB38, and thank you for the information, according to Virgin, I do need to plug both the scart and HDMI into the TV.
I am thinking about getting a scart adapter as I have a scart plug that I also use for the Wii and I am thinking that a 3 scart to 1 scart adapter will do the trick.

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Stuart's 2 posts GB flag
7:51 PM

I've got a HD TV with a variety of features
which cant be accessed unles I disconect it from my Sagecom Digibox. This as many of you will have guessed involves taking the ariel out of the Sagecom digibox and plugging it directly into the back of the TV thereby by - passing the Digibox. Does anyone know if this procedure is necessary or can it be carried out by reprogramming the digibox in some way or other.

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Eddy's 2 posts GB flag
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