Bill Williams (IT): Support Site
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By The Art of SCART
Bill Williams


Edit MessageUploaded - 14 Jul 2006 23:00

This is a topic describing how to connect up your Video devices using SCART


This is a long, long page. keep scolling down reading the portions with connection diagrams in sequence, because each builds on information in prior portions.

SCART
The SCART interface was proposed (I believe) by the French electronics industry as a means of connecting the video and audio signals between domestic entertainment equipment. It was taken up and is used extensively in Europe (including the UK) but is not used in the USA which uses phono cables.

Because the interface tries to cope with everything, the full cable contains some 21 wires and the 21-pin plug is somewhat big and clumsy. Often they are of poor construction and may fall out the socket in the equipment. In my opinion it is a grotty design, but we are stuck with it.

Unlike an aerial cable (described below) a SCART cable carries only ONE TV program at a time, but it may 'travel' either way in the cable, depending on the settings of the devices at each end of the cable. For example if you have two Video Recorders A and B and you connect them together with a SCART cable, then if A is playing and B is recording the signal passes from A to B, but if B is playing and A is recording then the signal goes in the opposite direction. Simplifying the description: To achieve this effect for Composite Video and Audio signals in the plugs there are 8 pins dedicated to OUT signals and 8 pins dedicated to IN signals and the OUT pins at one end are connected by the wires to the IN pins at the other end of the cable, that's 8 wires. For RGB (Red Green Blue) signals each colour has a pair of pins at each end and a fourth pair carries a signal designating which end is sending and hence which is receiving.

Composite Video is a kind of signal in which all the colours and grey-scale information is combined. The RGB video carries Red, Green And Blue colour information on separate wires, this gives better quality than Composite Video. Almost all video devices can handle Composite Video, but lower priced devices may not handle RGB.

The pin connections are shown in the last portion of this page and also at Link

Aerial Cable
The aerial cable brings the wireless signals down from the aerial to the first piece of equipment and is then daisy-chained (see diagrams below) from one equipment to the next by using short aerial extension leads. The cable is only two wires and is Co-Axial, which means that it consists of a wire in the middle surrounded by plastic insulation and then the insulation in turn covered by the outer wire which is in the form of a mesh of very fine wires. Then the whole cable is covered with a further layer of plastic.

An Aerial cable carries multiple TV channels as RF signals (=Radio Frequency) and consequently feeds into a part of each equipment called a Tuner, which is capable of separating one channel from all the others.

The direction of the signal is from the aerial, through each relevant device, to the TV set. Some devices such as a VCR will add their own output to the aerial signal on an empty channel as it passes through. Precisely which channel to use is chosen when setting up your equipment, usually by twiddling a sunken screw on the back of the equipment.

Of all possible output signals from a device RGB is the highest quality, then Composite Video and finally RF is the lowest quality. It is best to use the highest quality signal that your equipment can use.

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A device with a tuner, can use as input either the RF aerial signal or the SCART input. Due to their complexity, the digital TV signals can usually only be decoded by a digital receiver, either Freeview Digital terrestrial for an ordinary aerial, or a satellite receiver for a dish aerial. There are very few other domestic equipments at this date (2006) capable of decoding the digital TV signals.

Some (possibly most) digital receivers do NOT add their output signal to the RF aerial cable, so the digital TV channels are generally only received at other equipment via their SCART inputs. Hence after the digital receiver you can consider that the aerial cable carries only the old-fashioned 'analogue' TV channels. BBC1, BBC2, ITV, Channel4, Channel5, plus the output from a VCR or DVD recorder. The SCART cable, though it only carries one channel at a time, carries any channel from the digital receiver or from any VCR or DVD player in play mode.

===========
In general if you carry the Aerial cable chain right through (see below) to the TV set, you can be watching an old-fashioned 'analogue' channel while recording a different channel from the SCART cable.

==========
See also Link for more information on the SCART signals.

Revised on 15 Aug 2006

Bill Williams


Edit MessageUploaded - 14 Jul 2006 23:02

Basic Arrangement


The basic arrangement for modern digital TV is shown in the following diagram. The signal from the aerial enters the digital receiver is selected and decoded and comes out of the scart connector and then goes into the TV set via its SCART connector. Meanwhile the aerial is passed on to the TV aerial signal for watching the old-fashioned 'analogue' TV channels.




Revised on 15 Aug 2006

Bill Williams


Edit MessageUploaded - 14 Jul 2006 23:04

Basic arrangement from the rear of the devices.

Bill Williams


Edit MessageUploaded - 14 Jul 2006 23:06

Simple Addition of a Video Recorder or DVD Recorder.

When you add a single video recorder the second SCART socket of the digital receiver connects to the recorder. When recording both SCARTs of the receiver have the same signal, so it records what the TV would be seeing. When the VCR or DVD recorder is playing back the digital receiver either notices the special signal on pin 8 and shuts its decoding off and connects the output of the VCR to the TV, or else you may have to put the digital receiver in OFF state to get the same effect.





Revised on 15 Aug 2006

Bill Williams


Edit MessageUploaded - 14 Jul 2006 23:08

If the Digital Receiver is a Satellite Receiver.

There is no real functional differnce between how a satellite receiver is connected versus a terrestrial digital receiver.




Revised on 15 Aug 2006

Bill Williams


Edit MessageUploaded - 14 Jul 2006 23:09

If the Satellite Receiver also includes RF out.

I presume satellite receivers only include an aerial input and output if it is going to add the decoded digital channel to the aerial channels on the RF cable. Anyway, you daisy chain the aerial signals like this.



Revised on 15 Aug 2006

Bill Williams


Edit MessageUploaded - 14 Jul 2006 23:11

Daisy-chaining the SCART.

In anticipation of getting more equipment you can also use this alternative configuration in which you also daisy chain the SCART connections, like below.

So that the TV can 'see' the TV program selected by the digital receiver, the VCR must either be OFF or have the relevant SCART socket selected as its input. On its selector this will usually be known as AV1, AV2 or AV3 or even perhaps AV0 (consult the Instruction Manual of your VCR Equipment)



Revised on 15 Aug 2006

Bill Williams


Edit MessageUploaded - 14 Jul 2006 23:13

Daisy-chaining a VCR and a DVD recorder.

When you have two recorders, such as both a tape VCR and a disc DVD recorder one of the simplest configurations is to daisy chain both the aerial cables and the SCART cables.

So that the TV can 'see' the TV program selected by the digital receiver, the VCR must either be OFF or have the relevant SCART socket selected as its input. On its selector this will usually be known as AV1, AV2 or AV3 or even perhaps AV0 (consult the Instruction Manual of your VCR Equipment)

Furthermore so that the TV can 'see' the TV program selected by the digital receiver, the DVD Recorder must either be off or have the relevant SCART socket selected as its input. On its selector this will usually be known as AV1, AV2 or AV3 or even perhaps AV0 (consult the Instruction Manual of your DVD Recorder Equipment)

If you wish to record DVDs from your old VCR tapes then the DVD recorder should be closer to the TV on the SCART daisy-chain than the VCR as shown. Then when you set the VCR to Play and the DVD recorder to Record, it should work and you should be able to use the TV to see what is recording.

In theory if you set the DVD recorder to Play and the VCR to Record, it should work, but in practice you are likely to get interference from too many devices which will ruin the quality. Also purchased DVDs may contain a copy protection system which is an extra superimposed signal designed to screw up recording quality.





Revised on 15 Aug 2006

Bill Williams


Edit MessageUploaded - 16 Jul 2006 15:22

Adding a DVD player


DVD players only have a single SCART socket, so they have to be the first in the daisy chain. This means that you plug it into the unused socket of the digital receiver. If its TV SCART socket is output only, you may have to swap over the two scart leads in the didital reciever.

You may need to set the digital receiver to OFF or off-line for the signal from the DVD player to be passed through to the rest of the daisy-chain & hence to the TV.

On the other hand, the digital receiver may give priority to the DVD player and immediately pass the DVD player through to the rest of the daisy chain. In this case you will need to set the DVD player to OFF for you to be able view the off-air programs from the digital receiver.




Revised on 21 Aug 2006

Bill Williams


Edit MessageUploaded - 16 Jul 2006 15:23

Using a SCART switch,


If the SCART daisy-chain system does not work for you you may want to try using a SCART switch, such as this one: Link
This model is available in many shops, I've even seen it in our local Tesco's

With this you connect each device with a single scart cable to the switch. Deciding which device you are viewing or recording is determined by push buttons on the front of the SCART switch. This introduces a whole new realm of possiblilites for failing to set the right buttons and finding out afterwards that you recorded nothing or the wrong channel. Always check by setting the TV to see the output of the relevant recorder while setting up timed recording sessions.

The aerial circuits are still daisy chained as before.

With such a switch you get an extra facility, you can be copying from one video device to another, e.g. VCR tape to DVD while watching a live program from the digital receiver, or recording a live program from the receiver while watching a DVD or tape.

The round sockets on the scart switch can be used to connect the Video devices to your hi-fi audio amplifiers so that you can get high quality sound with your viewing. But the same facility can often be achieved by connecting to audio outputs of the VCR or DVD recorder too




Revised on 15 Aug 2006

Bill Williams


Edit MessageUploaded - 14 Aug 2006 22:45

SCART Pin Connections


RGB
15. Red Out, 0.7V p-p, 75 Ohms
13. Red ground, 0 Volts
11. Green Out, 0.7V p-p, 75 Ohms
09. Green ground, 0 Volts
07. Blue Out, 0.7V p-p, 75 Ohms
05. Blue ground, 0 Volts
16. RGB Switch
18. RGB Switch ground
Composite Video
19. Composite Video - Out
20. Composite Video - In
17. Composite Video Common, 0 Volts
Stereo Audio
01. RH Audio - Out
03. LH Audio - Out
02. RH Audio - In
06. LH Audio - In
04. Audio Common, 0 Volts
Function Select
08. Function Switch Out / 16:9 Switching
21. 0 Volts (General Ground) the outer case.
Not Connected
10. NC
12. NC
14. NC

Pin 8 provides function switching. Applying 9.5-12V to the pin will cause a compatible TV or VCR to switch to the AV (SCART) input. It may also switch on the equipment from standby. Applying 0V or leaving unconnected will switch back to TV. Some TV's also use this pin to select the aspect ratio. Applying 5-8V to pin 8 will switch to 16:9 mode. This may be used by DVD players to set TV to correct ratio. Connect ground to pin 14 or pin 18.

==============


Bill.


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