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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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22nd Sep 2020, 8:27 pm | #41 |
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Re: Old TV blamed for modern technology not working
The Sun: 'Despite binning the old TV and buying a new one, the couple say the internet signal is still terrible'
No surprises there! |
22nd Sep 2020, 8:27 pm | #42 |
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Re: Old TV blamed for modern technology not working
It will be the power supply (switch mode) I guess.
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22nd Sep 2020, 8:37 pm | #43 | |
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Re: Old TV blamed for modern technology not working
Quote:
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22nd Sep 2020, 10:07 pm | #44 | |
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Re: Old TV blamed for modern technology not working
Quote:
And once the interference was on one telephone cable, it probably went to all the others when it was bundled into the village cabinet. Frequency will be in the ADSL bands of 26 - 138kHz for upstream, and 138 - 1100kHz for downstream. Right in the usual frequency range of the typical SMPS. Richard |
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22nd Sep 2020, 11:50 pm | #45 |
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Re: Old TV blamed for modern technology not working
So my understanding Radiated interference below 30MHz isn't really considered only conducted since.
"Conducted radiation specifications cover emissions in the frequency range of 150 kHz through 30 MHz. A separate set of radiated emissions specifications covers the spectrum of 30 MHz and greater." "Electromagnetic conducted and radiated emissions are the radio frequency (RF) energy emitted by a product. The level of RF emissions are regulated to ensure that they do not cause unreasonable harm to other electronic products. At low frequencies (less than about 30 MHz) the conductors and cables of most electronic devices are ineffective as antennas and, thus, radiated emissions are not an issue." In other words there is virtually no requirement for "radiated emissions" below 30MHz If it were the case that the radiated transmissions were upsetting the broadband then it would be up to the ISP to make their equipment a bit less sensitive to interference? They could have kept their TV Or have I got that wrong. Cheers Mike T
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23rd Sep 2020, 6:30 am | #46 |
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Re: Old TV blamed for modern technology not working
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23rd Sep 2020, 7:59 am | #47 |
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Re: Old TV blamed for modern technology not working
Non-technical people nowadays have no idea that household equipment can radiate interference. That is ironical given the most homes nowadays radiate a lot more than in the past, mainly because of the switch-mode PSUs, the much larger number of devices in the average home and the low standards of compliance.
This would have been a bit different decades ago when many people realised that cars, and even planes, could interfere with the old analogue TV system and they could actually see that the snow on the picture coincided with a car driving past, or the wavy picture with a plane flying overhead. I was in the news business for 15 years. For the average non-technical reader, the story has a very high "weird stuff" quotient and therefore worthy of publication. You might even argue that it serves an educational purpose, in addition to its entertainment value (albeit mainly Schadenfreude in this case). I'm a radio amateur myself and used to suffer huge EMF interference pretty much across the HF bands at two specific times every day, each time for about half an hour. I tracked it down to my landlord, who lived on another floor of the same house. The interference came from an exercise treadmill, and was only generated when the belt was in motion. The problem was solved when I gave him ferrite-bead interference suppressors to put on the outside of the a/c line cord of the treadmill. Fortunately, he was an electrical engineer by training and therefore understood the problem!
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23rd Sep 2020, 8:07 am | #48 |
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Re: Old TV blamed for modern technology not working
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23rd Sep 2020, 8:18 am | #49 | |
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Re: Old TV blamed for modern technology not working
Quote:
Mike, the differentiation between "conducted" and "radiated" below 30MHz is largely a matter of recognising that most equipment that is tested - stuff that is in volume production mostly like TVs etc - is pretty small compared to the wavelengths involved. Which means that they won't radiate efficiently - so conduction is going to be the main means in which they cause interference problems. So if you took this TV *in isolation* and tested it for radiation, you would probably find very little problem. It will be the conducted interference, most likely coming straight back down the mains lead, and then into the house wiring, and in turn out on to the overhead wires that feed the house, that will have caused this. Once the signals are on such wires - they can capacitively cross-couple to other nearby wires, which as I pointed out previously look like could well be the phone network, since mains and telephone wiring appear to be sharing the same poles (looking at a pics of Aberhosan on Streetview). The solution is also very simple. Fit a decent filter on the mains cord to the equipment. It may have had one which failed. Or equally it may never have had one - particularly if its Chinese made equipment, because they are famous for omitting "useless" components like EMC filters. They are "useless" because they make no difference to the main functioning of the equipment they fitted to. |
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23rd Sep 2020, 9:48 am | #50 |
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Re: Old TV blamed for modern technology not working
Love that bit about the investigators left "Downbeat"! Then they called in a "Crack squad" with a spectrum analyser. Job sorted. 18 months to sort a simple problem or should have been.
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23rd Sep 2020, 10:03 am | #51 |
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Re: Old TV blamed for modern technology not working
This makes me think that the service was marginal anyway, and only needed a little interference to tip it over the edge towards unusable. Quite likely the guilty Bush was producing more noise than it really ought to have been, but how many similar sets are in service elsewhere without knocking over a whole community's internet connectivity? I disliked the simplistic and triumphalist tone of the original article, it smacked of deflection and seeking to pin blame on "the little man" whereas the truth was probably rather more nuanced.
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23rd Sep 2020, 10:35 am | #52 |
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Re: Old TV blamed for modern technology not working
Comments noted but remember the newspaper!
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23rd Sep 2020, 11:17 am | #53 |
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Re: Old TV blamed for modern technology not working
Sexton_Mallard's post yesterday about using a MW Rx to locate the RF spectrum used in ADSL is spot-on.
Back in 2017, after several visits by Openreach "Van mannies", and my incresing irritation at their inability to fault-find, eventually the local Foreman came out. A proper time-served old-fashioned BT linesman/telecomms technician. A much older guy. Upon seeing my BEME Loop D/F Rx he produced his wee old MW/LW Tranny out of his van. 'Stuff using a modern H/held line analyser' says he, 'we'll do this the proper old-fashioned way'. We traced excessive RF interference to an effing "horsey" electric fence about 1/4 mile away. But then, I'd already kent about it from the constant "clicking" prevalent on 80m. Worse when it rains, as the hignorant horsey neighbour couldn't be bothered to keep the grass cut around the perifery of his field's fencing. Whether the source is from a wee spark from a TV's EHT circuitry, faulty domestic appliances, or an electric fencer - the interference covers the whole RF Spectrum. Some frequencies often dominate - such as those in the MW band, which unfortunately are the same as used in ADSL down your telephone lines. BT divide their spectrum into "Bins" or Channels approx 4KHz wide.Basically, the more bins available(approx max of 276) - the better your Speeds. But then, your Modem & the Exchange equipment, upon detecting certain "Bin Frequencies" containing interference, will shut them down. Hence - slower speeds. They can, I believe, swop these channels about amongst your neighbours. So those who shout complaints the loudest - sometimes get better speeds than folk who keep stchum. For proper Telecomms expert advice - best raise a query thread in that Forum sub-section. Regards, David |
23rd Sep 2020, 11:17 am | #54 |
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Re: Old TV blamed for modern technology not working
On the occasions where I've been involved in things which appeared in newspapers, I must admit I'd have been hard pressed to have recognised the incident from what I saw printed.
So I tend to assume that all journalist-produced text is of similar quality unless proven otherwise. David
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23rd Sep 2020, 11:43 am | #55 |
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Re: Old TV blamed for modern technology not working
Jeremy Vine is doing a spot on this in his radio 2 show sometime between 12:00 and 14:00. Maybe we can glean a bit more info on the actual set.
Al
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23rd Sep 2020, 11:50 am | #56 |
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Re: Old TV blamed for modern technology not working
Hi
If it was a Vestel, which is probable, we've had a few in which the main smoothing electrolytic goes completely open circuit. Surprisingly, this causes only marginal picture interference and a bit of a background hash (not hum), but plays havoc with nearby equipment. |
23rd Sep 2020, 12:18 pm | #57 | |
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Re: Old TV blamed for modern technology not working
Quote:
David
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23rd Sep 2020, 4:32 pm | #58 |
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Re: Old TV blamed for modern technology not working
Don't worry the couple have surfaced for their Warholian 15 minutes.
Piers Morgan is sending them a TV to rival the one at The ODEON, Leicester Square. https://www.dailymail.co.uk/news/art...hysterics.html Stand down. All's well.
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23rd Sep 2020, 4:33 pm | #59 |
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23rd Sep 2020, 4:53 pm | #60 |
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Re: Old TV blamed for modern technology not working
Actually, if ADSL turns out to be so sensitive to LF/MF/HF QRM-generators and people get really grumpy about it and complain enough to get the tabloids involved.... there might just be a chance of getting all the crappy SMPS cleared out?
We could get out bands back! David
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