Telephone / Modem / Fax Plugs ?

[the_constructor]

Following an accident yesterday in the computer room, inwhich I tripped over the telephone lead to my newly installed (had machine for ages) Fax machine and ripping the wires the plug that goes into the back of the machine, can anyone tell me what the ref number of these small plugs are please so that I can make a new lead up. It is a 6 pin plug. I am not talking about the 631a plug that fits the BT socket, I am talking about the one that fits the other end. A supplier address etc would be most welcomed as well please.

[Harry Bloomfield]

the_constructor used his keyboard to write :

Maplin sell them,

You would also need a tool to put the plug on, so probably your best bet is to buy a new lead complete with the plugs fitted.

[Sparks]

That would be an RJ11 plug. If it has all 6 contacts, then it's a RJ11 6P6C If there are 4 contacts (but 6 positions) then it's a 6P4C (The outer two positions are empty in these connectors)

Sparks...

[Andy Burns]

At the equipment end you often get the smaller 4P4C connectors, RJ10(?)

[Dave Plowman (News)]

I think you'll find it difficult to source such a plug (RG 11) singly, and they're not easy to fit without the correct tools.

The same lead is used for most cordless phone base stations and modems and is available from Maplin etc for a few quid.

[The Natural Philosopher]

RJ10 usually.

[the_constructor]

Well I must thank you all for the quick response to my plea for help. I rang Brother UK the manufacturers of the machine and they told me it would be £22.05 + VAT + P&P I went down to local computer shop (mate owns it), rifled through his junk box and found a lead with the 6 pin plug on that I needed. Brought it home and set to work with test meter, spare BT junction box and a spare phone lead from my junk box. Although there are 6 wires in the machine lead, only 4 of them are used, now one would have thought that it was just a case of using the 4 wires in my lead and connecting to the centre 4 wires of the machine lead. WRONG ! Got it all sorted now though. Thanks again.

[David Hansen]

On Fri, 19 Jan 2007 09:32:38 -0000 someone who may be "the_constructor" wrote this:-

As well to buy a new lead. If you don't have the tools to make the connection then any lead you make will be iffy. Maplin have been mentioned, Netshop will make up leads for you though there is probably the lead you want on

[John Rumm]

Not usually on the line connection for a fax - I have only ever seen RJ11 there. You do see RJ10s on some phones - typically for the connection between the handset (or headset) and the base unit.

[John Rumm]

In fact you will probably find only two of them are used...

The most common layour seems to be the two central pins on the RJ11 connected to the two either side of the central pins (i.e. pins 2 and 5, where often 1 and 6 are not fitted) on the BT plug.

[Dave Plowman (News)]

Yes - pretty well all phone line connected stuff these days only uses two wires. Even if it rings. There doesn't seem to be a definite standard for the pins used on these RJ11 connectors though when only two are used - I've got a modem which uses different ones from a cordless phone. Since it's basically the US telephone connector I wonder why?

[Owain]

Because the UK line is on 2 and 5, or the outer wires of a flat 4-wire cord5, and the US line is on 3 and 4, or the inner wires.

Owain

[John Rumm]

Indeed, kind of why I said "most common". Lovely thing about standards, if you don't like one, choose another!

You do raise an interesting point however... perhaps the US socket wiring uses both left pins as A, and both left pins as B or some such arrangement. (don't think I have ever seen a RJ11 with only the left or right hand side pins wired!)

[Roger Mills]

Indeed. I've got several BT to RJ11 cables - and some (which came with phones) have BT 2 & 5 connected to RJ11 2 & 5, whereas others (which came with modems) have BT 2 & 5 connected to RJ11 3 & 4. I'm not sure which variety you would expect to find on a fax machine.

[John Rumm]

I think Dave was commenting on how some appliances seem to use 2&5 on the RJ11 and others 3&4. The 2&5 on the BT to 3&4 on the RJ11 seems most common, but you also get 2&5 BT to 2&5 RJ11. Hence if the US lead is RJ11 to RJ11 and wired striaght through (assumption), what is going on in the socket?

[Chip]

On Fri, 19 Jan 2007 22:09:53 +0000,it is alleged that John Rumm spake thusly in uk.d-i-y:

Oh yeah, you can't have too many standards for the same thing

The RJ numbers are frequently misused, even in official documentation that comes with modems/routers/telephones, they actually refer to the service(s) supplied by the jack, but with the 6 position, 2 contact (RJ11) or 4 contact (RJ14) connectors, in the US and Canada, pins 3+4 are for one line, and if present, pins 2+5 are for a second line.

There is also a 6 pin version with 3 lines present. (Line 3 being 1+6, this is RJ25C)

Confusingly there's also an RJ12 which also has 4 contacts but the outer 2 aren't for a second line, but for PBX off hook signalling to busy out exchange lines etc or for data wires, much like 1+6 were used on some systems using BT 631A plugs.

Oh yeah, and RJ45 isa very obsolete standard connection for modems, not 10/100baseT ethernet, although networks use the same connector ;-)

[Dave Plowman (News)]

Yehbut that doesn't explain the RJ11 using different terminals. I can't see them making a special PCB just for the UK so they can use a standard UK telephone flex.

[Dave Plowman (News)]

Ah - that could explain it. I wondered if they had two lines to the same point available in the US.

[gort]

Yes, they do.

Dave