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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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Sunday, 29 January 2012

11:17 AM

Toni: Just spotted that you had given an update, yes, concentrate on the scart switching device. You are also quite correct in what you say regarding older equipment, as you can frequently get these type of problems when connecting devices even when they originate from the same manufacturer let alone crossing brands.

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jb38's 7,179 posts GB flag
Thursday, 2 February 2012
7:43 AM

Thanks for your help I have succeeded in connecting 'TV out' Scart from Sky HD+ set top box to single Scart on Sony Theatre Centre. The HDMI links from both Sky box and Sony theatre centre are connected to TV the Sony centre to HDMI 1 ARC and Sky box to HDMI 2. This permits pictures even in HD to go to TV, while sound is linked through direct Scart to Sony centre. Have not worked oput a Scart link to VHS/DVD recorder yet and sysytem has to be manually changed on TV to select input source rather than via the Scart multi-switcher device, but surround sound works from TV and DVD's play through TV correctly with surround sound.

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Toni's 20 posts GB flag

8:53 PM

Toni: Thanks for the update! with one part of the content making me rather curious, that of you having said that the surround sound works OK from the TV, so could you confirm (or not) that you are referring to when viewing a Sky programme on the TV and not a Freeview one? as if by any chance it is the latter then for test purposes I would like you to remove the scart link between the Sky box and the Sony to see if the audio fails, as it should! if though it doesn't then that would suggest that the Sony's HDMI socket "is" responding to the TV's ARC facility even although its not listed as such.

On looking at the connections you have made between the various devices it appears as though the TV's single scart socket is not connected to anything, if this is the case then you should use that scart socket on the TV to connect the Toshiba's recorder's AV1 into, and with the recorders AV2 scart socket into the DVD/VCR scart socket on the Sky box, as in operation you will then be able to record from the Sky box "if" AV2 input is selected on the recorders input selector, and when anything is played back from the recorder it should switch the TV over to the recorder's output as the TV's scart should have auto-switching on that socket.

Likewise with this connection you should be able to record from the TV, as the recorders AV1 scart is capable of two way operation as is the TV's scart socket, so to record anything from the TV you first of all select AV1 on the recorders input selector, with playback exactly the same as previously described when referring to the recorders AV2 input.

Just to get back to the HDMI issue, if the test referred to in the first paragraph results in the audio failing then just swap the HDMI sockets over on the TV, as there is no point on having the Sony connected to the HDMI with the auto switch sensor if ARC is not working, as if No1 HDMI is connected to the Sky box then it should switch the TV over to Sky when the box is taken out of standby.

Would appreciate an update on results.

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jb38's 7,179 posts GB flag
Saturday, 4 February 2012
Toni Bucior
12:35 PM

Hi again and thanks jb38. Have tested with following results - Sony HDMI is 'out' only not 2-way. Surround sound only plays when Sky is 'on' does not play sound through Sony surround sound when TV 'Freeview' selected. Connections are:- Sky box HDMI to TV HDMI 1 (ARC) + Sky box Scart 'TV' to single Scart on Sony. Sony HDMI (out) to TV HDMI 2. The Toshiba DVD VCR recorder is connected by Sky Scart 'DVD/VCR' to Toshiba AV2 and TV Scart to Toshiba AV1. Unfortunately cannot check DVD recording as Toshiba has failed during process although internal 2A fuse is OK but might be down to moviing unit / removing and reconnecting cables although in nearly all cases the power has been switched off first. Hopefully a repair is possible or its a new or S/H buy but I don't need a HDD/Freeview unit.

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Toni Bucior's 20 posts GB flag

3:22 PM

Toni Bucior: I think you have experienced whats known as a classic case of "Murphy's law" applying, because nothing you have done can possibly cause that to have happened and the configuration of connections used is OK.

Just to verify though, I take it when you say "internal" are you meaning the one inside the casing of the DVD/VCR or is it just inside the 13amp plug?

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jb38's 7,179 posts GB flag
Toni Bucior
6:14 PM

jb38 I suppose Murphys is another word for it but I was thinking more S**s Law, must be co-incidental as DVD VCR was working OK even during the cabling rearrangement process. Hence have located a local repairer to giove it the once over apparentyly quite common if no power requires two diodes to be replaced? Will have to await repair or replacenment but do not want an all singing and dancing HDD Freeview DVD VCR set.

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Toni Bucior's 20 posts GB flag

6:42 PM

Toni Bucior: Yes, it just one of these type of things that can happen at the very end of having done something reasonably successfully, an equipment breakdown! although as a long term engineer myself I know its nothing you have done that could possibly have caused it.

Anyway, maybe you could give an update once you are back in business.

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jb38's 7,179 posts GB flag
Friday, 10 February 2012
9:34 PM

I really hope someone can help me. I have a TV and a DVD recorder, both with built-in Freeview. They've been connected and working fine for over two years, and I've been able to record one channel while watching another via the TV. The aeriel is connected to the TV, with a SCART lead connecting the TV and the DVD recorder. However, there now seems to be a problem with the connection between the two machines. The signal to the TV is fine, but when I switch from TV to DVD, it says NO SIGNAL, and effectively this means that the TV and DVD recorder aren't communicating. If I connect the aeriel to the DVD recorder instead of the TV, it says NO SIGNAL and I lose the ability to watch via the TV's Freeview tuner. I've tried disconnecting everything, switching off and on again, but nothing seems to work. If anyone has any ideas, I'd be very grateful.

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Laura's 1 post GB flag
Tuesday, 14 February 2012
Jim F

11:04 AM

Laura: The aerial lead should be connected to the DVD aerial input.
You then need another coax cable to connect the aerial out socket to the TV's aerial input.
The SCART connection doesn't carry UHF signals (just video and audio).

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Jim F's 141 posts GB flag
Friday, 17 February 2012
Mark Petersen
12:17 PM

I have just bought a Technisat HDFV set top box. My current set up is a Sony HD ready TV linked up to a Sony HDD/DVD recorder and a Sony VHS machine. I am currently able to record a different channel to the one I am watching on the TV.
I want to be able to do the same with the set top box connected up - Technisat technical helpline are not very helpful - they say it is impossible. Is this true? Anyone got any ideas?

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Mark Petersen's 4 posts GB flag
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