TV Interference

macshac · Mar 24, 2007, 16:19:14

Hi All
Heres a beaut.I have a panasonic TV about 10 years old and it was the last largest tube screen available about 38" I think.
I was monitoring my broadband noise with router stats lunchtime today when I saw the monitor shoot down to Zero.
Switched the TV off ,returned to 6db.
I have disconnected Sky+ box and tried everything but it is definately the TV causing the interference.
I do not have the sky+ box connected to the phone line.
Has anybody had this problem and is there a solution apart from getting rid of the TV?

jupiter · Mar 24, 2007, 16:29:42

If you look at this url you will see that the problem with plasma TVs has been recognised:
http://forums.speedguide.net/showthread.php?t=206018

You need to move the TV as far away as possible from your phone wiring and computer equipment. Read through the thread though for other tips.

macshac · Mar 24, 2007, 16:46:08

Hi Jupiter
Thanks for your reply but I did not make myself clear.The tv is a large analogue tv about 1997 not plasma(I wish could afford).
It is sited in my lounge and the netgear dg834V2 router is sited in a bedroom with a hall and closet in the hall between the bedroom and the lounge.
Admittedly the walls are partition rather than solid and I would say the tv is 40 feet from the router.
Very strange?

Inactive · Mar 24, 2007, 16:54:10

It is probably a 36" Panasonic, the largest screen CRT ever made for the UK.

It is strange that it has an effect on your Broadband connection, especially at that distance.

Have you tried it with the Sky Receiver disconnected completely from the TV, ie' remove the scart lead etc.?

Does the aerial lead pass near your router?

Clutching at straws a little, certainly one I have never heard of before.

macshac · Mar 24, 2007, 17:04:37

Hi Inactive
Yes it is the 36" beautiful picture beats the pants off laser and LCD which is why I really dont want to replace it until I have to.
I have disconnected scarts ,TV aerial and ran on sky box only but no difference and in all my tests it only happens when I turn the TV on.
This is really strange?

jupiter · Mar 24, 2007, 17:30:51

So when did this start to happen? Exactly what might have changed in a recent period to cause this symptom to appear?

Or is it that you have only just noticed the effect?

How is the working of your broadband connection affected - loss of sync or drop in connection speed, or does it appear to have no effect in practice?

macshac · Mar 24, 2007, 17:39:49

Hi Jupiter
That is a long story.
I have been having major problems maintaining speed because of an unstable line for some time in fact moved from BT because of a load of problems.
It is only since i came to Idnet that people have been trying to help.
Rikbean gave me the details of the router stats programme which I have only been using for a few days.
It is this that has identified the TV effect and that was only because I was watching the router stats when my wife switched on the TV.
I am hesitant to use it noew as I have only just got my speed and downloads sorted.

jupiter · Mar 24, 2007, 17:58:15

OK, now I've read the earlier thread I see the background.

If I've got it right, you have now sorted out some of the earlier problems and have a better understanding of what is going on with your line and have pinpointed a source of interference. At that attenuation of course your line is never going to be greased lightning.

But the earlier thread suggests you became happy with the performance of the connection, so I wonder whether you would still be happy with it if you didn't know the effect of the TV! It is possible to get sucked into tinkering believe me. And you don't say what happens to your use of broadband when the TV is turned on - does the dip in sync speed actually matter to what you use the internet for?

Is it too unkind to say that as the analogue signal is to be switched of before long it may be time for a new set (but not a plasma one)?

MoHux · Mar 24, 2007, 18:40:18

Mac, I think it is possible the telly has developed an R.F. (Radio Frequency) leak somewhere inside. It could be being picked up by the mains lead and transmitted to the router that way.

Is it possible to try a different telly?

If it is R.F. leakage it may pay to get a friendly telly engineer to check it out, as it could be just a shield has moved. An RF filter on the lead may help.

macshac · Mar 24, 2007, 20:46:50

Hi Jupiter
you are probably right but as I have Sky+ the TV does a good job.
I think it is about time to modernise.
It is painful as the set cost £2500 ten years ago thats £250 a year.
But I think you are right it is time to let go.
Last thing does it do any harm to speeds etc. if you switch off the router at night and back on when TV is not watched?

jupiter · Mar 24, 2007, 20:54:54

Lots of people routinely turn off their routers overnight. It is fine to do so.

What is best avoided on a long line with high attenuation is turning the router on again late afternoon or evening because that is when general sources of interference are at their worst. This is then likely to give you a lower sync speed when you reconnect.

So off overnight and on in the morning works well. Also avoid turning your router on and off repeatedly within a short space of time as this can 'fool' the exchange into thinking your line is unstable and, in response, also lowering your sync speed.

Inactive · Mar 24, 2007, 23:46:53

Quote from: macshac on Mar 24, 2007, 17:04:37
Hi Inactive
Yes it is the 36" beautiful picture beats the pants off laser and LCD which is why I really dont want to replace it until I have to.
I have disconnected scarts ,TV aerial and ran on sky box only but no difference and in all my tests it only happens when I turn the TV on.
This is really strange?

A very wise decision indeed, I have yet to see any LCD or even Plasma TV that will give results like a good quality CRT like your Panasonic.

It may well be worth trying a portable TV in situ where your normal TV is located to see if you can replicate the problem.

You could also try swapping the scart lead from your Sky Receiver for a different one, just in case that is leaking interference.

Interference is more likely to be coming from external sources from outside of your TV, rather than inside electronics, although anything is possible.

Try the above and let us know.

Rik · Mar 25, 2007, 10:38:06

Quote from: macshac on Mar 24, 2007, 16:46:08
It is sited in my lounge and the netgear dg834V2 router is sited in a bedroom with a hall and closet in the hall between the bedroom and the lounge.

How does the phone wiring run relative to the TV, eg do you have an extension adjacent to the TV for the Sky box? It's that relationship, rather than the one with the router, that I'd be looking at. Have you done the bell wire removal, I can't remember?

macshac · Mar 25, 2007, 12:01:17

Hi Rikbean
The TV is in the lounge and the lounge has no phone line in it the nearest is the master socket outside the lounge door in the hall.
Sky box not connected to any phone sockets at all.
I am going to try surge protectors on the TV and on the computer set up where the router is to see if this helps at all.
Thanks for your help so far.
You are advising so many people I wonder how you remember it all.Yes I have removed the bell wire.
At one time I thought it might be the Ring curcuit for the TV which the sky box was powering but I removed all that and found it only happened when I turned on the beast and returned to normal as soon as I switched the beast off!!!!!

Rik · Mar 25, 2007, 12:05:15

Hi Mac

When Sky was installed, was it connected to the phone (as would normally be the case)? If so, what's happened to that wiring?

Ferrite cores on the TV mains lead, and possibly aerial lead, may also be worth trying. What telephone wiring do you have, eg extensions from the master?

macshac · Mar 25, 2007, 12:20:35

Hi Rikbean
When sky plus was put in I ran a long extension lead from the hall to the lounge as a temporary measure and when the 12 month agreement was up removed the lot and now do not have any phone paraphernalia in the lounge,Wierd int it.
I went out and bought two surge protectors this morning and put one on TV equipment and a larger one on my computer equipment no go I got exactly the same result as soon as I switch on the TV bang down to zero on the noise monitor so it has to be transmission.?

Rik · Mar 25, 2007, 12:48:13

I'd be surprised if this wasn't your telephone wiring picking up RF, that's my gut reaction to that kind of noise 'surge'. What happens if you connect the router to the test socket behind the master (assuming you have an NTE5?).

macshac · Mar 25, 2007, 12:52:46

Thanks Rik
I do have a test socket behind the master socket but cannot reach it with my modem as I am connected by ethernet not wireless I was when on BT because of the broadband Hub.
I think I will go for a wireless modem to the test socket before I buy another TV.
Try that first much cheaper option.

Rik · Mar 25, 2007, 12:58:03

Cheapest option is a long ethernet cable, you can go up to 100m is a single segment. That will allow you to test and eliminate all your internal wiring. If the TV problem persists, you have a major RF issue to deal with, if it clears, you need to sort your wiring. If the latter, it could explain some of your other issues.

macshac · Mar 26, 2007, 09:58:40

Hi Rik
I have solved one peoblem by buying a Samsung LCD 32" which does not spike as much as the other but more and more I am noticing that domestic equipment causes noise spikes.
This all points to the ring main or is it that all domestic equip gives off RF signals.
Is it normal to have these spikes on the monitor or is there a way of supressing the electrics in a house to improve the noise level on the phone lines.
I have ordered a Wireless Netgear dg834n the new one which will be here tomorrow which I will connect to the test socket and monitor from there .
It isnt a problem I am just interested to see how much I can improve the line noise.

Rik · Mar 26, 2007, 10:40:10

Hi Mac

Everything you say points to a problem with your internal phone wiring. Was it installed by the builder or by BT?

I'd suggest you read through the sticky on wiring self-help, here, and check that things are as good as they can be.

I do get problems with noise but, as far as I possibly can, I have eliminated internal sources, and BT have checked my wiring (however, they charge for doing this). For this reason, I have a target noise margin at 9db. I sacrifice a little speed, but I gain stability. That fact that your issues seem to be cyclical makes me wonder about nearby heavy industrial plant, possibly radiating noise into the mains.

jupiter · Mar 26, 2007, 10:49:58

Glad to hear things are going well. It is correct that much domestic equipment creates RF interference - central heating switches etc.

Another phenomenon is surges or spikes on the mains supply. What some people do is to connect their router via a mains surge protector, but you can pay a lot to get really effective ones. Much more likely are the RF sources and here it is improvements in internal phone wiring which will best reduce it - following the advice Rik has given

It is the old story really, if the way you use your broadband connection is adversely affected by the interference you experience, then it is worth spending a bit of money. You will never achieve perfection in terms of noise reduction cos the entire home phone technology set up is now coping with signals it was never designed to carry.

Be interesting to hear how your new wireless router affects things.

Inactive · Mar 26, 2007, 10:51:58

Just to add;

The most common form of electrical interference within domestic households are the following;

Central heating boilers.

Refrigerators.

Other items that have built in thermostats.

As Rik says, external interference may just be causing the problem, now that it appears it wasn't just the Panasonic TV.

PS Beat me to it Jupiter ...

macshac · Mar 26, 2007, 11:00:21

Hi All
I think I should have my noise margin raised to 9 how does one go about this.
Rik no industrial around the bungalow is on the cliff top at westward Ho in Devon so residential all round.
The problem seems to be with electrical motors I am not bothered just intrigued now to see how to improve it.
I do now suspect the construction of this bungalow is involved.
The bungalow was built about 8 years ago with metal framed partition walls instead of timber so essentially I have large metal antennas behind all the internal partition walls and there aint nothing I can do about that .
Lets see how the new netgear performs at least I can change channels on that.
Should be here tomorrow!!!!

Rik · Mar 26, 2007, 11:52:52

Hi Mac

Ask IDNet support to get your target margin raised, it's a fairly simple task. It will drop your sync speed a bit, but stability is better than raw speed, imo.

From what you say, the construction may help or hinder. If it's earthed, it might just be helpful. If not, it's certainly going to draw any noise there is around. One thought, is there much shipping in the area and possibly a coastguard radio station, that would have the potential to cause issues. Do you know of any radio hams or CB freaks in the area?

How about the phone wiring, was it put in by the builder or BT. Have you checked for a split pair, as this would make it very prone to noise pickup. How many sockets to you have after the master, and do you need them all?

The new Netgear will make no difference in the signal after the test socket, all it will do is establish whether the issue is in your internal wiring. The wireless channels used will only affect wireless reception, not the exchange signal as such.

Ultimately, if this proves to be external RF interference, it may be a case of getting the SFI team involved, I know of one user who was being affected by the passing of trains, and the electrical noise they generated.