Plasma TV and ADSL2+

Hi there,

I just wanted to canvas opinions on who has interference issues with plasma TV's and their ADSL2+? And what have you done to eliminate it?

My main TV is a 2011 Panasonic plasma display and it's mounted on the wall in the lounge using it's own fused spur (no ferrite cores). It is wired to the router in the loft via a direct length of cat5e cable with a ferrite core at the TV end.
I have an 8 port switch mounted about 4 feet below it that has the Sky box, PS3, Blu-ray player and Xbox360 plugged into it. This again is connected directly to the router in the loft via a length of cat5e cable. No ferrite core.
The router is in the loft and connected directly to the master socket (also in the loft) via a Solwise 'high performance' RJ11 cable and ADSLnation filtered faceplate. The cable from the drop wire to the master socket is a single piece of cat5e cable.
The router power cable has a ferrite core around it, as does the extension power block that the router is plugged into.

Things I plan on trying:

1. Ferrite core around the TV power cable. Difficult as I'll need to take the TV off the wall and it's a (large) 2 man job.

2. Make a foil 'tray' for the router to sit in. How effective will this be considering I need to do it and not hinder the wireless antennas?

Any suggestions and advice woul be much appreciated.

Paul

Sorry if I've missed it in your post but are you saying your TV is causing noise?
i.e. I take you've monitored things with the TV on/off?

There have been a few Plasma TV threads in the past on TBB so prob worth a search...

Hi,

Yes, definitely the TV. I don't thing it's RF simply due to the proximity of the ADSL kit to the TV. So, it must sticking the nastiness up the mains.

I've 'googled it' too and seen a few threads but, none of them seemed to actually solve the issue, other than buy getting rid of the TV. That's not an option for me as I love my TV.

I've put a choke around the TV power lead and it seems to have little to no effect. I'm considering a mains conditioner next...

Paul

You still seemed to have missed out on detailing the symptoms you are getting. Unless you are hoping we can guess based on the remedial actions you have tried?

Ah yes, you're right. Apologies.

Essentially, my SNR drops by between 0.5dB and 1dB when the TV is on.

I've been doing a little research and it seems a 'delta suppression filter' across the spur where the TV is connected to could be worth a shot...

Paul

In reply to a post by youngsyp:

Essentially, my SNR drops by between 0.5dB and 1dB when the TV is on.

That's where you should have started. It was like going to the Doc and saying that you are ill and you've taken pill A and pill B and laid down and you are still ill .

That's not much of a reduction in the NM if you really mean "BY" and not "TO".

Does it just reduce or are you having resyncs at same time.

Could you be confusing TV ON with nighttime?

You come home, turn the TV on at night and then notice NM drop. You conclude it was switching on TV that caused it, but it could just be the normal small drop that happens after dark.

Get another ferrite ring and wind the ADSL lead to the master socket a few turns round it at the router end. Your lower SNR is likely happening due to this lead acting as an aerial. The ferrite will not reduce the real ADSL signal at all. The DC lead can also act as an aerial but you seem to have that one sorted.

As your Router is up in your loft, a metal tray would generally reduce the WiFi signal reaching the main inhabited parts of your house.

Similarly, the WiFi signals from the user devices back to the router would almost certainly be attenuated.

As the WiFi signals are very small in the first place, try moving the router to a more accessible location in the main body of the house, unless of course, other circumstances prevent that.

An analogy would be trying to illuminate the complete interior of the house, using a single torch bulb, LED or similar at the present router location.

If the router has an external aerial, it may be possible to replace it with a directional one etc.

Within the loft, you may be able to improve the situation by moving the router to a location further from the plasma TV, although clearly that may have implications regarding using a phone extension cable - but relatively cheap to try.

It seems strange that the phone master socket is in the loft, as usually they are fitted in less inconvenient places such as the back of cupboards, to allow "easy access" for phone line tests.

===========================

I haven't checked the details of plasma TV screens; but generally plasma is associated with electrical interference, such as emanates from lightning, arc welding and the like.

Regarding ferrite cores for cables, I have seen and used split ones, which may be more readily fitted to your TV, possibly avoiding the 2-man lift.

Noise affecting ADSL margins via mains bourne sources is rare.

More likely to be RF radiated from the plasma itself. though saying that a drop of 0.5 to 1dB, assuming you have a 6dB target value to start with should not cause any issues.

Is the ADSL lead from filter to modem, a twisted pair cable, or the normal cheap one supplied with the router? Also you have done all the usual things of removing ring wires etc

That's not much of a reduction in the NM if you really mean "BY" and not "TO".

Agreed, not really worth worrying about. Now, if it were flooding the signal with errors, when turned on. That would be a different story.

If the OP is quibbling about .5 to 1 db snr loss, I'd say watch MORE telly and less router stats.

In reply to a post by XRaySpeX:

Could you be confusing TV ON with nighttime?

Yes, even I can tell the difference between daytime and nighttime.

SNRM is forced to around 4.3dB, from the ISP's 6.3dB. As already stated above, when I switch the TV on, the SNRM drops by between 0.5 and 1dB. It doesn't cause a re-sync or drop the connection. Granted, in isolation, that's nothing to worry about. Although, you could argue that a single device causing such a marked change could be something to worry about...
At night however, when there's all the other sources of interference present, that extra 0.5 to 1dB could cause re-syncs and /or instability.

@sbrads: The ADSL lead is made from cat5e cable so, noise shouldn't be an issue. Any length of cable can act like an antenna however, the twisted nature of cat5e cable is there to prevent this as it 'rejects' noise.
Regardless, I've put a ferrite core on it already and it made no difference. Thanks for the suggestion though.

@eckiedoo: Yes thanks, I'd already decided against using foil anywhere near the router case. The antenna's would negate its effectiveness anyway.

And I've already fitted a ferrite core to the TV mains cable and it's made no difference. Again, thanks for the suggestions.

@MrSaffron: I agree mains bourne interference affecting noise margins is rare but, I've seen it before with a Thompson Sky receiver.
The issue I have with believing it's airbourne interference is as mentioned above, the distance between the router and TV and that the interference would have to penetrate through 2 floors.
Yes, the ADSL cable is constructed of twisted pair cable. I don't have a ring wire as the master socket is wired directly to the drop wire on the outside of the house via cat5e cable. Only the 'A' and 'B' legs are connected. The 'usual things' have all been taken care of as I was extremely mindful of the network set up when the house was wired up (see first post).

@Zarjaz: Again, yes in isolation 0.5 to 1dB isn't a lot. However, if we examine the big picture and consider what happens at night, that extra reduction could cause instability.

As the SNRM is dropping, I'd expect there to be an increase in errors too.

By way of a further update, I made a mains filter from a delta suppression filter and varistor, wired it across where the TV's spur is wired into the mains and it made precisely no difference. So back to the drawing board.

Paul

Edited by deleted (Sat 07-Jul-12 19:16:33)

Does it not strike you, with all this extra fancy hardware gubbins you fitted not having any effect, that you might be barking up the wrong tree?

Barking up the wrong tree in what sense? Please elaborate...

Paul

Have you used an AM radio to try and identify which bit of kit is the worst offender noise in the home?

That the issue is connected with mains interference and introducing some combination of suppressors, conductors, condensors, resistors, varistors, vibrators or any other electrical "...ors" into the house power supply will cure a BB problem.

Edited by XRaySpeX (Sat 07-Jul-12 20:15:51)

No, not done that yet, mainly because I don't have access to one and that I was convinced it was the TV sticking nastiness up the mains.

If I can get hold of one, I'll certainly use it to pinpoint the exact issue, if it can.

Paul

Maybe so but, that's why I was asking the question(s), in the hope that enlightened people such as yourself could point me up the right tree.

Paul

Yes Plasma telly's have been known to be a source of REIN, but then so have Sky boxes, ethernet switches, communal aerials, robot lawn mowers, electric fences, etc, etc.

Use of an MW radio will most likely convince you that the telly IS the cause, they always kick out a lot of noise, but is it the right sort of noise ?

@Zarjaz: Again, yes in isolation 0.5 to 1dB isn't a lot. However, if we examine the big picture and consider what happens at night, that extra reduction could cause instability.

... but is it causing instability ???

As the SNRM is dropping, I'd expect there to be an increase in errors too.

Well, is it racking up the errors when it lowers ??

In the specific circumstance I'm writing about, It's clear it is the TV. There's no question about it. I can see it clear as day. When I switch the TV on, there's a downward spike in the SNRM of around 1dB. It will then settle around 0.5dB lower than it was when the TV was off.
When I turn the TV off, the SNRM goes straight back up to it's target level again.

Paul

.... and to ask again. What actual fault is this causing ??

And the majority of sources that reduce noise margin are carried over the air, rather than through the mains

Interestingly the three sources of inteference I have had to deal with in my house were my old laptop mains lead, the power supply for my christmas lights and having a phone plugged into the bedroom exgtension (now use a cordless). On top of that I cannot have my DAB radio plugged into the same extension lead as my hi-fi amp without getting earth loop hum through the speakers.

There are no issues that i know of with a plasma tv and a router however they are connected to a router providing the mains cables on both applications have the Ferrite core fixed in place as outlined by Panasonic and with the approved Ferrite core that came with the TV

If, as seems likely, it's airborne RF noise from the TV into the router, then you may find that simply moving the router a little and/or rotating it could achieve a null spot. Another thing to try is a 'shorted turn', basically just a loop of wire round the router, each end connected to each other. Difficult to do it with the TV though.

Well, I thought it was contributing to a drop in connection. However, my connection seemed to drop at a specific time last night despite the routing holding on when the SNRM was at around 1.7dB for an extended period.
I'm feeling a little more philosophical today. Clearly the TV isn't causing this drop in connection even though it is contributing to the overall lowering of the lines SNR.

Paul

Pop round here then and I'll show you one.

The ferrite cores on the TV's power cable and at each end of the interconnecting ethernet cable, made no difference to the interference. Panasonic often get things (very) wrong.

@sbrads: I'll give it a try, thanks.

And one thing I've negated to mention up until now and of course has a major bearing is that I'm on a FastPath datastream. I'm toying with the idea of asking Vivaciti to switch interleaving back on though.

Paul

Edited by deleted (Sun 08-Jul-12 11:58:51)

In reply to a post by youngsyp:

Pop round here then and I'll show you one.

The ferrite cores on the TV's power cable and at each end of the interconnecting ethernet cable, made no difference to the interference. Panasonic often get things (very) wrong.

@sbrads: I'll give it a try, thanks.

And one thing I've negated to mention up until now and of course has a major bearing is that I'm on a FastPath datastream. I'm toying with the idea of asking Vivaciti to switch interleaving back on though.

Paul

I think you will find Paul that the Panasonic TV is not the culprit i would say far more likely the router picking up a bad source of REIN from a nearby application than the tv in which i know very well

So it's just a huge coincidence that the moment I switch the TV on, the SNRM drops and the instant I turn the TV off, the SNRN rises back to 'normal' again?

If you care to google the phrase "plasma TV affecting ADSL", you'll see a huge number of hits where people have seen the same or similar issues to mine. Just because you've not experienced it, doesn't mean it doesn't happen.

I thank you for the condescending tone of your response though.

Paul

As a matter of interest, you have never said whether you are switching TV ON from completely OFF or from STANDBY, as many do these days?

In reply to a post by youngsyp:

So it's just a huge coincidence that the moment I switch the TV on, the SNRM drops and the instant I turn the TV off, the SNRN rises back to 'normal' again?

If you care to google the phrase "plasma TV affecting ADSL", you'll see a huge number of hits where people have seen the same or similar issues to mine. Just because you've not experienced it, doesn't mean it doesn't happen.

I thank you for the condescending tone of your response though.

Paul

well I'm sorry you find my post condescending and that is most regretful but where all the equipment is powered by a proper 6/8 mains filter with RF i myself have never seen your problem but i have seen it in many houses that do not have a filtered main socket sorry i couldn't have helped you

http://www.amazon.co.uk/Tacima-Conditioner-Frequency...

Edited by NICK_ADSL_UK (Sun 08-Jul-12 15:16:27)

Hi,

It makes no difference whether I switch the TV on from off or from standby.

Please find below a link to an image showing exactly the issue. The red circled area was recorded when I turned the TV into standby, left it for 4 minutes or so, then switched it back on again.

http://i51.photobucket.com/albums/f365/youngsy/Route...

Paul

In reply to a post by NICK_ADSL_UK:

well I'm sorry you find my post condescending and that is most regretful but where all the equipment is powered by a proper 6/8 mains filter with RF i myself have never seen your problem but i have seen it in many houses that do not have a filtered main socket sorry i couldn't have helped you

http://www.amazon.co.uk/Tacima-Conditioner-Frequency...

Ah, that's not what you wrote originally though. You wrote there are no problems that you know of. There was no caveat with regards to using a mains conditioner... You've also contradicted yourself with the final part of your response. You clearly have seen it before but, don't experience it yourself.

I use one of the linked items for my AV kit. As the TV is on the wall, it has it's own fused spur so, I couldn't use one of those for its power delivery. However, buying one of those mains conditioners for the router is one of my next steps.
If I recall correctly, I've cured an issue with ADSL before using a mains conditioner.

Paul

Just in case anyone else is experiencing similar issues, I 'think' I may have improved on the problem.

When I wired up my cat5e cable from the drop wire to the master socket in the loft, I only connected 2 pair per leg, leaving another 2 pair un-connected. Not only do I have a street light directly infront of where the drop wire comes out of the ground but, I suspect the cat5e cable runs very close to the TV. As most of you are aware, those un-connected pairs would have been acting as an antenna for any airbourne noise.
So, I've now connected all 4 pairs up so that each leg of the drop wire has 2 pairs of the cat5e cable connected to it. Last night I didn't get a drop in connection like I'd normally get and the action of switching on the TV causes a 0.2 to 0.4dB drop in SNRM where as previously, it would cause a 1dB drop. The drop now seems to have some relationship with the target SNRM that's set...
Interestingly, some form of noise disappears at around 12.38am as there's a distinct increase in SNRM at that time. Figuring out what that is is the next step.

I tried a mains conditioner on the router and that made zero difference. But, I will be putting a choke on each end of the feed to the master socket and at each end of the two other long cat5e runs I have that run near the TV.
I've also bought a new 'pre-filtered' socket to replace the master socket and faceplate. The current faceplate is around 6 years old and the type are known to fail so, it's a pre-cautionary step. The new socket also features better connectivity which should hopefully reduce any resistance further.

Other things I've done:

Verified master socket connection polarity (-50v DC on 'B' leg).
Swapped ADSLnation Pro ADSL cable for Belkin high speed ADSL cable. This increased attenuation but, the ADSLnation cable is 1m long whereas the Belkin cable is 3m long. Needless to say, I've switched back to the ADSLnation cable.

Paul

In reply to a post by youngsyp:

When I wired up my cat5e cable from the drop wire to the master socket in the loft, I only connected 2 pair per leg, leaving another 2 pair un-connected.

Could you elaborate on this "2 pair per leg" as I have either not understood correctly or you've done somthing very wrong!

It could just be your definition of pairs and legs but I would regard a "leg" as a single wire within the (twisted) pair. Hence, a pair consists of 2 legs (twisted). Therefore when you say 2 pair per leg that suggests 4 legs (ethernet) per 1 leg (dropwire), which, although possible, is not good wiring practice!

Are you saying that have terminated 2 ethernet pairs (as pairs or splits) to EACH incoming leg (wire) of the dropwire pair.

For example dropwire a-leg to ethernet pairs 1 and 2, and b-leg to ethernet pairs 3 and 4?

(Sorry, difficult to express with words, a picture would be better!)

If this is what you meant (or similar) then this is effectivley untwists the pairs leading to
longitudinal imbalance along the ethernet cable and consequently EMI noise ingress if the cable is of sufficient length and proximity to mains etc.

Just in case you have done this. I would advise you do this instead:

Dropwire pair 1 a-leg (orange) to ethernet pair 1 a-leg (white/blue stripe)

Dropwire pair 1 b-leg (white) to ethernet pair 1 b-leg (blue/white stripe)

Unused ethernet pairs 2, 3, 4 (orange, green, brown) leave disconnected each end (or earth either end if inclined)

Unused dropwire pair (green/black) leave disconnected (unless you have a 2nd line LOL!)

Also incoming cables are not always "dropwire" and so colour coding may be different. However, you have already identified incoming pair so you simply need to make sure it is just connected to the 1 pair of ethernet (if not already).

Hope that helps a little.

Edited by deleted (Sat 21-Jul-12 00:12:41)

When I was using my old Netgear DG834 router, when I turned my Panasonic plasma on ADSL2+ would completely cut out. It wouldn't lose sync but I was getting virtually zero throughput. I got put back on ADSL and then the plasma didn't affect my connection. A few months later I disconnected the ring wire at the master sockets and all extentions (my router isn't connected to the master socket) and I replaced the router with a Billion Bipac 7800n. I then dared to try ADSL2+ again. The plasma no longer affects my connection and I'm syncing at 15 meg.

Yep - that "ring wire" can be a killer whatever flavour of ADSL you are on!

Just have wires connected to terminals 2 and 5...!

In a nutshell, yes, that's what I've done. 2 out of the 4 twisted pairs to each drop wire leg.

Could you explain how that effectively un-twists the 4 pairs and induces EMI? As mentioned, I saw a definite improvement in the noise on the line and stability of the line which would contradict your statement.

At a very basic level, what I've done is reduce resistance by using more copper.

Also, wouldn't the un-connected ethernet cables act as an antenna for noise if they're not terminated?

I'm not trying to be argumentative but, as mentioned the practice doesn't tie up with your theory.

Thanks,

Paul

If the original wiring was

Blue with white stripe and
white with blue stripe

What you should have done is

Connect Green with white stripe to the blue with white strip at end end

then

White with green stripe to the blue with white stripe.

This should lower resistance, and keep noise amountity. The resistance over a few metres wiring in the home though is minimal compared to the drop in the street to the exchange

The drop wiring is orange and white I believe...

Clearly the cable between the socket and the exchange will offer the greatest resistance in the circuit however, any reduction is worthwhile especially when it just involves connecting a couple more wires.

Regardless, I'll give the theory a test at the weekend and see if it improves noise on the line. Again, it'll only mean disconnecting a few wires.

Paul

In reply to a post by gomezz:

Interestingly the three sources of inteference I have had to deal with in my house were my old laptop mains lead, the power supply for my christmas lights and having a phone plugged into the bedroom exgtension (now use a cordless). On top of that I cannot have my DAB radio plugged into the same extension lead as my hi-fi amp without getting earth loop hum through the speakers.

reply to old post but... Problem with extension may be it is wired from junction box before the master. If so, disconnect it. It will be terrible with a phone plugged in, but also quite bad even without. You may get quite a bit of extra speed.