Scart

Introduction.

A few days ago, I purchased a new DVD recorder. Why you might ask !. Well I was actually looking for a DVD player when I saw the DVR in a shop marked up as costing £24.99 !. It was obviously a mistake so I went in and mentioned it to one of the younger generation assistants. The assistant looked at me as if I was a moron (such perception in one so young!) and gave me a hard time ... so I bought it at £24.99. The next day I saw that they had put a price reduction on the same model ... and it now only cost £79 !. OK that is how I ended up with a DVR with no Freeview tuner. That wasn't really a problem as all I wanted was a DVD player and already had a Freeview box and a VCR. I was later planning to buy a hard drive type DVR with a twin Freeview tuner so that my wife could record from one tuner while watching programs on the other.  Unfortunately the model I was interested in didn't have a DVD player built into it ... hence my need for a separate DVD player or DVR. All I had to do was connect all the boxes together using SCART leads and everything would be wonderful ... after all that is what SCART is for ... isn't it ?.

SCART.

Scart is a French orientated standard for the interconnection of video and audio devices and is only used in Europe. This means that you will only find SCART sockets on equipment intended for the EU market. The name comes from Syndicat des Constructeurs d'Appareils Radiorécepteurs et Téléviseurs, but in France the system is usually known as Péritel. The standard is based on a 21 pin socket and cable system, that are supposed to 'daisy chain' the devices together in such a way that everything works perfectly with everything else ... Ho Ho Ho !.

SCART pin connections.

Although SCART is supposed to be a standard, interconnection cables can be bought that are either fully wired or part wired. They also come as either an input or output cable !. The difference between the two is shown in the table below. The table is for part wired cables which should work in most domestic cases. 

Another feature of the system is that many electronic boxes such as Freeview, Sky, VCR's, DVD's etc have two SCART sockets on them but one is often only part wired. It should be obvious that there is plenty of room here for confusion !. In addition to the audio and video signal lines shown in the above tables there are also two status lines. The one we are particularly interested in is on Pin 8. Pin 8 works in two states, either input or output and has different functions in each state, for example it can control the aspect ratio of the TV, it can signal recordings, it can switch the TV to it's AV input (ie SCART input) etc.. Again plenty of scope for system conflict and confusion, for the unsuspecting. Some cables and SCART adaptors are fitted with an "input / output' switch. An example is available from http://www.tvcables.co.uk/cgi-bin/tvcables/AD001.html

A chat about boxes.

My problem was that I had to interconnect a TV with a single SCART socket to a DVR, A Freeview box and a VCR. The fact that my old TV only has one SCART socket means that it only has one AV channel. If it had two then I could connect Freeview to one and the DVR and VCR to the other channel, which would have avoided one source of conflict. Part of the problem can be seen by referring to the connection table, where it can be seen that there is only one 'video' input on a cable or socket. If we allowed both the DVR , Freeview and the VCR to be on at the same time there would obviously be a conflict between the three video signals being fed to the one line at the same time. Also with the three devices all sharing a single pin 8 .... any device when switched on could switch the TV from it's terrestrial channel to the AV input, with a loss of TV picture, sound and control. In the simple case only one device feeding the TV can be allowed to be powered up at any one time. The problem here is what if we want to watch the Freeview signal and record at the same time. This would mean that the Freeview AND the DVR would be powered up at the same time. A similar problem occurs when we set the DVR timer to record a program. After we set the timer (using the TV screen), the DVR powers down to 'standby'. We can now watch Freeview on the TV with no problems ..... until the DVR timer powers up the DVR to make the recording and now we have both the DVR and Freeview boxes powered up at the same time. In my case the DVR took over total control of the whole system, with no TV Freeview picture and a complete loss of control of the TV. I could not even switch off or control the DVR and had to wait until the timer finished the DVR recording. I have to admit that at this stage I am not sure how this conflict occurs and need to investigate it further. To this end I have ordered some cables, adaptors etc from EBAY to see if I can solve it with the connectors. For example it may be that I need to change an output cable to an input cable. 

Manual switching boxes.

These allow you to select one box as an input to the TV ... out of many. They come in many different types and sizes, but all basically have a number of inputs and usually a single output (to the TV). A typical low cost version available from Argos and Maplins is .....

This one has three SCART inputs, selected by the switches on the right hand side. The top SCART socket is connected to the TV.  This box also allows one channel to be watched on the TV while a recording is being made on another box. it also breaks out video and audio signals for other purpose. I have ordered one of these to try out. They are available for less than £10.

Remote controlled switching boxes.

For those who do not want to get out of their chair to manually operate the above switching box will be relieved to discover that they are are also available with a remote control. Yes ... yet one more remote controller !. Again these only allow one box to be connected to the TV at any one time.

Automatic Switching boxes.

If we introduce some logic circuity into the switching box it is possible for it to detect which box was switched on last and automatically connect to it.  Some of these will allow recordings to be made from one input channel. I have no experience with them and do not know how well they sort out conflict problems. I guess that you get what you pay for. Curry's sell one for about £24. You could always try it and return it if it doesn't work in your case.

Remote controllers.

As the number of boxes increase ... so do the number of remote controllers !. The answer to this problem is to purchase a single multi-purpose controller, such as an 8 in 1. These can typically be programmed to control up to eight different devices. Some of the latest can do even more such as solve the Volume control punch-through problem and can also be programmed for macro's. A macro is a short simple program that will allow a single key depression to send out more than one code. For example if you want to watch a DVR recording, you can program the play button to also switch the TV to one of it's AV channels and switch off both the unwanted Freeview and VCR boxes and select DVR inpu s-VHS number two as well !.  So macro's can be used to avoid system conflicts and simplify operations.

Remote controller codes.

Multi-purpose remote controller key functions can be programmed in a number of ways. First the controller may come pre-programmed.  Another method uses control code groups that are specific to a particular make and model of box. For example to program all of the important buttons on a controller to work with a Bush DVR, you only need to know the code group, in this case it is 3004. The modern trend is to include the control code in the model name ... ie, Bush DVR 3004.  The website for a given controller will be on the manufacturers web site, which you can find using GOOGLE.  Most of the more modern multi-purpose controllers have a 'learning facility' and can learn the codes of a particular remote.  In the case of old equipments, web sites may list several codes for a particular manufacturer's models. For example, it may list eight different codes for VCR's. In this case, simply try each code until the remote power button works. 

The future of the 'remote'.

The number of devices that can be controlled by a remote increases by the day. Heaters, lights, machines, computers, door locks, ventilation, alarms, kettles can all be remotely controlled. It makes it more important to reduce the number of remote controllers that one needs to use. Most modern multi-purpose remotes can be programmed to control such devices.

As you can imagine a multi-purpose controller that had enough buttons to control a vast range of equipments would look very complicated and still not provision for the needs of tomorrow, so another new approach was made by introducing touch screen controllers. At first glance these may appear to be just a gimmick, but they have a bright future and are available for less than £8 on EBAY.  The important thing about these is the fact that it has a screen and everything you seen on the screen is put there electronically ... which means that it can present data in many different ways. For example if you want to operate the DVR you simply press the DVR button and the screen will now display only those buttons needed to control your particular DVR. The older style of screens used to have a fixed number of function buttons, for example it may have one marked "SKY" which is totally irrelevant if you don't have it installed and use Freeview or FreeSat instead. So modern touch screen controllers allow you to edit the names allotted to each button graphic.  This means that it is possible to have a special screen layout for controlling the house lighting and you can call your 'kitchen' exactly that !.

Have fun !.

Post script.

I have now solved my problem .... or rather the TV did when it blew up !. I now have a nice new , flat screen TV with built in Freeview and at least two AVG channels.