Master socket ADSL wiring

[garyevs]

Hi

I have recently checked the SNR ratio on my line and it is very low (1-2 db). I think I may have a problem with the way my socket is wired. It was installed by a BT engineer some years ago, but it just does not look right.

Before I had broadband, I had a second line in the house, BT ran both lines off the same cable. I also had a hardwired extension cable running to other phones in the house. I would not expect the engineer to have been confused by all this, but you never know.

The second line has now been removed and I no longer use the extensions in other areas of the house, though the cables are still in place.

I have an original BT "ADSL v1.0" master socket. The ADSL line runs via a RJ45 plug directly to a RJ11 socket, which my router plugs into. I just have one cordless phone plugged into the phone socket. I do not have a filter on this phone, as I understand that this socket is already filtered.

I had a look at the reverse of the backplate as well, and the socket is wired as follows:

The 2 blue/white wires from the incoming cable are connected to the terminals at the top of the reverse of the backplate (A & B). All the other wires in the incoming cable are unused.

The 2 blue/white wires and 1 orange wire from the (now unused) extension cable are connected to the 3 terminals on the rear of the RJ45 socket (the orange cable in the centre).

I have hardwired extension cables in my house and others so I am not a complete novice, but I cannot see any way that this is correct. I am amazed that it works at all, and I imagine that this must be the reason for the very low SNR on the line.

Am I correct in assuming that the blue/white wires in the incoming cable are the only ones that need to be connected to the socket (via terminals A & B) ?

If so, does the RJ45 socket also take its signal from terminals A & B, and can I therefore just disconnect the wires to the rear of the RJ45 socket?


Any help would be appreciated....

Cheers

 

[plugwash]

your wiring sounds absoloutely correct to me, with a BT faceplate filter both the terminals on the back of the filter and the phone socket on the front are filtered.

you can disconnect your extention wiring from the back of the filter plate if you want but I doubt it will make any difference to your ADSL.

 

[Space cat]

The 2 blue/white wires and 1 orange wire from the (now unused) extension cable are connected to the 3 terminals on the rear of the RJ45 socket (the orange cable in the centre).

Let's be clear about this. The RJ45 socket is the one you use for your broadband modem router? There is no way that phone extension wires should be attached here whether they're in use or not. All phone wiring belongs on the filtered side in parallel with the standard phone socket.

If you were to use phones on the extensions they wouldn't be filtered. Even with no phones the broadband signal is rattling around your extension wiring, bouncing off open ends and coming back to the RJ45 socket out of phase. Do you have any other terminals on the back of that face plate?

PS: You're right about the two incoming wires. That's all you need for a single phone line. The broadband signal uses the same wires but at much higher frequency.

 

[plugwash]

on a BT filter plate the terminals for the phone extention wiring are behind the RJ45 socket. This DOES NOT mean they are connected to it.

 

[Space cat]

This DOES NOT mean they are connected to it.

Thanks plugwash. I took garyevs' description literally. On more careful inspection, this

the 3 terminals on the rear of the RJ45 socket

should have been a clue.

 

[OLD]

SNR 2db is very bad you need to isolate the internal wiring and get the bt line tested if the problem is with them you should be provided with a new line .With those figures the line should be very noisy so check this also.

 

[Infidel]

Disconnect all extension wiring from the nte plug your modem router straight into the backplate and run the snr test.
You only need THE A+B wires for i/c line, also check the rear of the backplate no fried spiders or dampness leading to furry deposites on teminals nice and dry and clean,you could also give the i/c wires a tug just to make sure they are nice and firmly held under the terminals and have not been nicked on installation.
If that doesn't resolve the problem try a quiet line test either just dial any single digit to remove dial tone and listen for any crackles pops or hums which could indicate a problem with your line (try it with a corded handset straight into the backplate as cordless handsets tend to have various noises induced via the r/f).

There is a BT automated line checker but I hesitate to put the number up until cleared by mods as although known by many BT get a bit tetchy about it.

You might also have a look at the condition of the external wiring is it overhead are there many joins in the lead in is it old grey wiring etc.
Also your speed is very dependent on your distance from the local Exch and condition of the u/g network.

Your in that sticky situation where it's going to get batted about from Isp to BT. Just run all your tests from the cable head (Nte backplate) with nothing else connected to clear yourself and any intnl cabling.
Hope this helps.

 

[MarkBarl]

Let's be clear about this. The RJ45 socket ....

.... coming back to the RJ45 socket ...

This is being picky I know, but in an effort to be technically correct. What you are referring to is in fact an RJ11 socket with 4 pins in it. Used in telephony equipment, modems and DSL equipment.

RJ11

An RJ45 sometimes referred to as a Cat 5 socket has 8 pins. Used for data connectivity.

RJ45

 

[plugwash]

iirc the socket on the BT filter plate is actually a RJ45

 

[c128]

you can disconnect your extention wiring from the back of the filter plate if you want but I doubt it will make any difference to your ADSL.

Not my experience. In fact, it made all the difference - night/day in terms of connection up time - see here:

//www.diynot.com/forums/viewtopic.php?t=95077&postdays=0&postorder=asc&start=0

Now, some months on, and with no other changes to the internal wiring, the broadband connection mentioned in the above thread is still working reliably and faster than it ever did...

 

[plugwash]

You are using unfiltered extention wiring with seperate filters on every point, that is a totally different situation from the one the poster of this thread has.

 

[MarkBarl]

iirc the socket on the BT filter plate is actually a RJ45

You are quite correct, my mistake Why they used RJ45 when all other ADSL equipment uses RJ11 makes no sense.