My ITV/C4 Freeview channels have disappeared - what can I do? Is it my SCART ca
Brian Butterworth published on UK Free TV It is a feature of television signals that they can be effected by the weather. Aside from the obvious damaged that can be caused by wind or torrential rain, the onset of summer can cause a more intriguing problem called "inversion".
Basically, when the sun heats up the land, the hot air can get trapped below cold air at high level. This creates an "inversion layer" which acts like a polished mirror to TV signals. This causes two problems: you can receive both the original and a reflected signal from your own transmitter (on analogue TV this appears as "ghosting") or interference from TV transmitters that are normally too far distant.
The ITV/C4 multiplex of channels (ITV-1, ITV-2, ITV-3, ITV-4, CITV, C4, More4, E4, Quizcall) use a transmission "mode" called 64QAM, and it is sadly much more prone to these problems.
So, whilst a loft-mounted aerial will provide reception at some time, it will fail at others. The only real solution is to mount the aerial (or a new Class I aerial) outside on a pole, but some people report that changing the cable from the aerial to the set-top box to the high-grade satellite cable can also help.
The SCART connection, by the way, only carries a single TV picture, not the Freeview transmission multiplexes, so if this is disconnected it will result in degradation to every channel at once.
All questions
In this section
Monday, 20 May 2013
Dennis: Thanks for getting back.
It turned out to be a simple thing. I suppose hindsight is a wonderful thing though.
With analogue, issues with aerial faulty leads was easier to pinpoint as the picture would change as you moved it.
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jb3811:21 PM
Matt: Many thanks for your update / image shack view of the boxes in question as this helped to clarify a few aspects concerning your installation, but though unfortunately adding another mystery!
The black HI Isolation box seen in your picture is (or should be) a relic from the past of about 18 years ago, as this type of device was primarily used back then for satellite selection purposes when Sky was running a parallel analogue and digital service from two different satellite positions, analogue being 19.2 and with digital being 28.2 degrees, and this box enabled a resident of a flat fitted with a dish facility to select the satellite that matched their receiver, hence analogue and digital being seen on your manual.
The mystery I refer to being, that this switch box should have no connection with your Freeview signal unless the system has been modified at some point in time, as its the box on the left hand side that's of more interest, unfortunately though the framing of your picture clipped the view of the cables leaving both boxes, and although the input to the splitter box is seen to be coming from behind the wall I am unable to see if its two output leads disappear upwards or cross over to the black isolation box, maybe you could advise on this.
The other thing I wondered about concerned the TV socket on the wall plate, insomuch is it a standard female coax socket? or is it an "F" male connector? that is a threaded type socket.
Further advice dependant on reply.
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Tuesday, 21 May 2013
M
Matt3:44 PM
Hi JB
I think one output leads goes upwards and the other goes into the wall - I will check when I am home.
Both aerial sockets in the flat are just a normal co-ax cable with female socket - no screwing involved.
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jb389:34 PM
Matt: Apart from checking the cables out maybe you could clarify on a point with regards to what you had mentioned in your 8.21PM posting, and I refer to when you had said that your success was short lived and that the channels had all vanished again, was this after you had made any changes or did it just suddenly happen? because provided that you have NOT tried to retune that particular TV after this event then the channels you had managed to store in the tuners memory should still be there, therefore there is no reason why they should have vanished again except by something external to your apartment having been responsible.
That of course is assuming that the channels found after the rescan were actually stored? if not done automatically on your TV as some sets do not automatically store them, and if not then they will be lost again when the set is switched off.
You should try the test again by pressing the "A" button and trying out the master bedroom TV rescanning as necessary, because if the channels return again then I would like you to carry out a test whilst viewing something on the TV, and that is to unscrew each of the two "out" "F" connectors "in turn" on the splitter box and note if one of (if any) kills reception on the master bedroom TV.
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Wednesday, 22 May 2013
M
Matt9:55 PM
Hi JB
I have just rescanned both TV's. Main room is the same - BBC channels but poor quality. Master bedroom TV is picking up the ITV ones! Poor quality as well though - very jumpy and flickery.
I have had another look at the splitter box and as you look at the picture - out of the 2 'out' cables, the right hand side one goes into the splitter box on the left hand side above the 'a' button - everything else goes into the wall.
I unscrewed the out cable on the right hand side and it killed the reception in the master bedroom TV - i wasnt able to get a hold of the other cable to unscrew that though.
Does that help at all?
Thanks in advance
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Thursday, 23 May 2013
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jb3812:02 AM
Matt: Yes, that does up to a point help clarify the situation insomuch that it suggests that the communal aerials input feed cable is connected into the splitters "IN" socket, passing through the splitter and then leaving on its right hand "OUT" socket which in turn is then linked into the top left hand socket on the switch box, the middle connection on same apparently going to the master bedrooms aerial socket and why nothing was received in the master bedroom until you pressed the "A" button which completed the circuit, of course in saying that this circuit would likewise work in the reverse, but I doubt if it is.
However connections being made this way makes me suspect that someone has made alterations to the original system and that is what is causing the confusion, but to enable me to complete the picture I would like you to temporarily remove the wall plate enough to be able to see how many coax leads leads are connected into the rear of the plate, and maybe you could also advise as to whether or not you see "SAT" being mentioned next to a socket on the front of the plate.
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jb388:51 PM
Matt: Further to that already mentioned, much as I hate to say this but I was having a rethink about the entire situation surrounding your problem, and when taking all you have said into account I am now of the opinion that spending time cable tracing is not going to result in the problem being resolved mainly because that fault finding of this nature really has to be carried out the aid of a proper signal meter for the purpose of checking where the signal exists as well as where not, something that's really essential because faulting without same really involves working in the dark and where time consuming educated guesswork is the order of the day!
Another aspect that has to be taken into consideration is that your installation still has to be looked at from the basic fact that you have no control whatsoever over the signal entering your property, and even although the concierge may well have reported that none of your neighbours are experiencing any problems this cannot be taken as a 100% cast iron guarantee that the fault is not with the incoming signal, as your neighbours are not necessarily on the same aerial feed as yourself.
However the one thing that I do find rather puzzling is by you having discovered that the signal in the master bedroom returned by your action of pressing the "A" button, this linking the middle connection on the black box with one of the outputs from the splitter, because "if" your problems have only been recently experienced and with to your knowledge nothing having been altered, then I fail to see how your master bedroom TV could have been receiving Freeview with button "B" pressed in.
As mentioned in my previous reply, I have a sneaking suspicion that the connections on these boxes have been altered at some time for purposes unknown, although this could possibly have been carried out when analogue satellite TV ceased to exist thereby making the boxes "A" input redundant, should it have been used for that purpose, and although there are various permutations that can be made with these connections the basic fact still remains that if you had previously been receiving Freeview on "both" outlet points then the problem is not one of a connection error, therefore I feel that the cause of the problem will only be revealed by an on site inspection, which to be perfectly frank about it should be the responsibility of concierge and not the occupiers of the apartments, as I am sure that the occupiers have a levy to cover this aspect built in to their charges.
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Tuesday, 28 May 2013
C
Catherine5:05 PM
Hi JB38
You gave me some help a few weeks ago and asked me about whether my aerial was horizontal and about a signal check. I posted the details below, I wondered if you were able to offer any more help?
Thanks again,
Catherine
catherine
Friday 10 May 2013 3:30PM
Hi jb38
The aeriel is horizontal and the TV is a Matsui M26DIGB19 (26" HD READY DIGITAL LCD TV) and yes I have the instrction manual.
I don't know how to do a signal check to note the mux number. When on ITV2+1 I press display on the remote and it comes up with the EPG channel number (ie 27), the signal strength and the title of the programme, but doesn't say the mxu channel.
Thanks again,
catherine
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jb3811:40 PM
Catherine: Sorry about the delay in replying, as although I did see your reply on May 10th in answer to my query regarding the model number of the TV in question, but though I did not answer straight away simply because that your answer raised a problem that's frequently experienced when dealing with devices especially made for chain stores (Curry's in your case) the problem referred to being a total lack of info on the model in question, as user manuals for same cannot be downloaded albeit that amazingly I do have the technical service info for the set, however this does not give info on anything connected to the menu system used by the TV.
That said, if your communal aerial is mounted horizontally then it will likely be facing Mendip @ 15 miles / 185 degrees , therefore the programmes that you have reported as having difficulty in receiving are spread across the three commercial transmitters, the mux channels (not EPG) used by them being : 48 - 56 -52.
As the menu system used in your TV is unknown, first of all scrub the channels already stored by carrying out the procedure of removing the aerial followed by carrying out a complete auto tune, then once having verified that nothing is stored by witnessing a "no signal" warning when you press the programme guide, what to do next is go into the "set up" menu / tuning and look for "manual" being indicated, this usually always located next to "auto tune", if you see it click on it and that should come up with a box that you enter the mux channel number into, should you manage to get to that point enter 48 followed by pressing search or scan and storing anything found, then temporarily exit the menu and press on the programme guide to check the list of commercial programme channels found during the scan and with ITV3 (10) being first on the list, giving an update on results when further info can then be given.
I should say though, that on checking back all you have said since your original posting is inclined to suggest that your problem could simply be caused by a combination of the signal strength being received from the commercial services being on the weak side, but with this being coupled to the tuner used in your particular TV being of the less sensitive variety.
The reason for saying this being your report that one of your neighbours has perfect reception on the channels that you are having problems with, and so another thing you could do is to try using another jumper lead between your TV and the wall plate or box, this action preferably taken before carrying out the aforementioned procedure.
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Saturday, 8 June 2013
S
SABEL9:53 PM
Oxford
ityv3 used to be ok on Ch.9 but this now showsNO SIGNAL retuning now shows ITV£ on Ch.800but this still shows ITV3 no signal but on some occsions this shows momentarily a flash on the bottom streamer icon of the programme title e.g POIROT. ergo programme is reaching my set but does not hold.What to do next?
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SABEL's: mapS's Freeview map terrainS's terrain plot wavesS's frequency data S's Freeview Detailed Coverage
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