All posts by jb38
Below are all of jb38's postings, with the most recent are at the bottom of the page.
nick: With regards to your posting of 3rd @ 06.09pm, even although you personally may not have come across it, but the problem you refer to "can" also be experienced on some large screen "analogue" TV's connected to an external receiver via a scart lead and with the reasons for on both large and small being twofold as follows, although the latter reason mentioned is not so commonly experienced on larger screen TV's basically because that they are usually fitted with more substantial power supplies.
The first reason can be caused by the level of the video signal being fed into the TV's signal processing circuitry via the scart lead being a little on the high side, and which dependant on severity of can in some instances cause it to break through into the TV's audio circuitry resulting in video signal buzz being heard through the speaker, the frequency / intensity of changing in sympathy with the content of the picture, this type of problem having the potential to affect large and small sets alike, although reducing the video signal input level generally cures the problem.
However the other and more common reason is a little more complex, and to put it in a simplified way is basically caused by the TV having a poorly designed power supply by not having adequate filtering between the supplies used to power the various stages such as the receiver / frame timebase / line output stages/ and of course the audio IC, however the problem is mainly concerned with the section that makes the most demand on the power supply, namely the line output stages.
The problem being that bright high contrast images containing plenty of white content makes the maximum demand on the power supply line used by the line output transformer's driver transistor, the demand as touched on before varying in sympathy with the content of the picture, but though because its linked to the content / make up of the picture complex signals are involved and so there is always a high level of ripple currents circulating in the DC power line feeding this section, likewise increasing the contrast to give a somewhat more vibrant picture increases the difference between high and low in these currents thereby increasing the ripple content and which can find its way into the audio circuitry on a set with a less than ideal level of filtering.
People who use Sky boxes coupled into their older CRT analogue TV's via a scart lead sometimes experienced this type of problem if they had set their Sky boxes picture control setting to "high contrast" rather than medium, but likewise noticed that some of their other TV's connected via the sky boxes RF modulator did not show this problem, basically because that unlike in the case of a scart input and where the TV's signal processing circuitry is at the mercy of the signal level fed into it via its scart socket, anything received via an RF input passes though a series of processes that irons out excesses
Please note though that this has been put in a greatly simplified fashion.
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Graham Guthrie: Many thanks for the update as I was curious as to what the outcome would be as you had exhausted all avenues that could be explored whereby the only way the problem was likely to be sorted out was by an engineer making on on-site visit.
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peter johnston: The info you require is detailed on the undermentioned link, although a particular point to note being that you have to be in possession of an active Sky viewing card and which is a once of payment of I believe £25.00.
Please note that you will not be able to record anything on a Sky+ box unless you take out a subscription (around £12.50 per month) purely for the purposes of being able to use this facility "on its own" without access to Sky package channels, but its best to contact Sky for the latest up to date info as they are always changing conditions and you may possibly be able to have those two combined.
However as far as your dish is concerned, this has to mounted outdoors and with a clear view of a S/SE skyline
How to get BT Sport with BT | Help | BT.com Help
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Mike: You will have to remove the dishes LNB and replace it with a quad type then run a second cable from same to the box, quad LNB kits being obtainable from a number of e-bay suppliers for around £10.00 or so and are extremely easy to fit, caution being exercised that you do not move the dish!
This said on the assumption that your new Freesat box is a twin tuner PVR (recorder)? However you will presently be able to use it for viewing provided that the single lead is connected into the LNB1 input.
By the way, the roof aerial can only be used for a terrestrial based Freeview box, as Freesat and Freeview are not compatible with each other.
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nick: Pleased to have been of assistance, although I did mean to enquire if your TV is using an RGB or composite video connection via the scart lead? because should it be the latter and you are still one for carrying out experiments? then you could have doctored the scart connector plugged into the box to incorporate a potentiometer across pins 17 and 19 (17 ground / 19 comp video out) the wire on 19 being removed and connected onto the middle connection of the variable resistor (about 1K) as this would enable you to adjust the video level from the box to suit the TV its connected into.
The only downside of this being, that if the CRT on your portable has lost some of its emission resulting in a lack lustre picture, then reducing the video input level although curing your audio problem will have the opposite effect on the picture.
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Brian : Thanks for the info on the Sony model in question, this really being for notebook purposes as well as enabling me to check the service manual for same to find details of tuner fitted into this model as I do find what you have reported to be slightly puzzling as far as the Panasonic is concerned, as in my experience anyway Sony has never excelled to any great extent over any other well known brand and especially Panasonic, albeit that the latters signal strength / quality indicators do have rather lively extremely fast responses to changes in the signal levels over that seen on many other sets, some of being rather sluggish meaning that a signal could dive up a down and yet it would appear to be stable, mabye the latter is not such a bad thing though!
By the way, I would take what you have been told by the digital hepline people "if" thats whom you were talking to? with a proverbial pinch of salt, as although what you have been told can in many instances apply in other cases it doesnt dependant on what is involved, therefore the only thing I would suggest you do is try and verify if anyone else in your locality are also experiencing problems with reception at around the same time as yourself, of course making sure that they are viewing the same programme channels as well as ensuring that they are viewing whatever from the same station, as checking back on your postings I cant say I noticed you having mentioned where you are located, this info being important when evaluating causes of reception problems.
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Brian: Although this is neither here nor there if your reception has previously been OK prior to the commencement of the engineering works at Rowridge, but now is known you are located at 20 miles away from said transmitter can you confirm that your aerial has been mounted vertically?, the purpose of being to enable you to obtain maximum signal strength from the three commercial muxes and which only radiate at 200kw on vertical polarity, whereas 50Kw on horizontal.
By the way the BBC and ITV stations radiate at 200Kw on both polarities, the other point being that in cases where the signal is intermittently diving downwards then its not so much turning the aerial than can "sometimes" help, but moving its mounting position slightly to the left or right of its present location.
Although as having previous said, I wouldn't alter anything as yet but wait until Rowridge gives the all clear.
P.S: You aerial should be vertically mounted irrespective of anything else that may have been discussed.
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Viv: You can purchase a suitable booster from Argos, an excellent variable type givig up to 20db gain made by SLX as seen on the their catalogue page 507, item number 107 / 1533 @ £11.99.
The other types seen Philex are also good quality devices but have a fixed output of a maximum of 18db, although this is reduced on the 2 - 3 - and 4 way types dependant on how many outputs are being used.
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Dave: Are you sure that the jumper lead being used (if) is in perfect condition? try wiggling the connectors at each end of the lead about whilst viewing the picture, as the Toshiba's analogue picture should not be that terribly different from that obtained on the LG.
Try temporarily connecting the coax cable from the Sky box directly into the TV whereby bypassing the magic eye.
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Friday 6 September 2013 12:09AM
Graham Guthrie: Interesting! as that puts a different complexion on the problem all together, that is provided that the others referred to in the block actually do have HD capable TV's fitted with DVB-T2 tuners? as by rights you should have really good reception from Belmont.
Pity you cant try the short wire instead of the communal aerial test? because if your signal from Belmont is powerful then reception of sorts should be possible on about 6 feet of wire connected into the TV's aerial socket, this being followed by either carrying out an auto-tune or alternatively manually tuning in C28 as this channel would not be listed in the programme guide.
If though you have an engineer paying you a visit tomorrow, then an update on the outcome of said visit would be appreciated.