Bt headscratcher

Eddiesparks · Jul 31, 2013

Went to do some work in a large flat - extra sockets on a radial, few extra lights, chandelier put in etc. we disconnected a (not used) secondary bt point for chippy as it was in a cabinet that was being rebuilt. Twisted wires together that were together in the socket. By the way there's 2 separate bt lines. One they use and one they dont, used to be hooked up to fax machine, now not used. The sec. socket was on the line they didnt use. I find the master for the unused line. Works fine. All wired in newer twisted pair cable.

Following so far?!

I then find out the line they use is not working after our works. We didnt touch this line. It consists of just a master (not net5 test master style - looks more like a sec. socket but had capacitor on it so must be master? I may be wrong??!) and no secondary sockets. One blue one white going to 5 and 2. (older style cable not twisted pairs) - what the hell is going on?!?! It must've been us but i cant see how...?! Ps i tried 2 different phones and had no joy. Also there wasnt 48v across any of the cores. No signal?!

UNG · Aug 2, 2013

Silo said:
Not when i used to install PABXs, it was always 50v (sometimes peaking to 60v) when ringing.

A PABX is a different beast to the PSTN

Silo said:
I've just checked and it seems things have changed since these old bones used to install telephones, it used to be 50v on hook & ring to 20v off hook (or there abouts), it seems that now it's nominal on hook at 48v ring at up to 85v and off hook as low as 6v!!!

I guess thats what you get for not being in the game constantly!

The biggest change for phones was the introduction of the System X exchanges starting in the mid eighties

Eddiesparks said:
When i ring the line that i am havimg probs with i get the 1571 'this person is on the phone' message

Also, like i said the master which is not working is the only point out of three in the house to have non twisted pair wiring, older style i think. And it's NOT on an external wall. The wall it's on backs onto another flat. Not very BT is it?!

Probably the GPO then

Eddiesparks said:
This makes it v hard to trace to the street!!

You just need the right kit a tone tracing kit makes it quite easy. If you look outside the building and identify the incoming telephone cables it may give you a clue as to the internal cable route if it is fed from the other flat it may be an old shared service line that has been converted to a DACS line (one line serving two subscribers )

Eddiesparks · Aug 2, 2013

Thank you so much for your help everyone i sorted it.

The master i thought was for the unused line was actually for the one in use that wasnt working. They used blue/white for 5 and orange/white for 2. ( i thought better to use the twisted pairs?!?!)

Then it went to a point in master bef which was disconnected and reconnected. (By my labourer!!) then to the point that wasnt working. For some reason this last point had a capacitor on it as if it were a master. The incoming to the bedroom was in blue/white and orange/white then the out was blue/white and white/ orange. How strange is that?! Also there was a junction box somewhere between them because the bedroom outgoing was two twisted pairs but faulty (not anymore!!) socket was not in twisted pair. Also the final socket was blue and white for 5 and 2. (But outgoing from second last one in the chain was blue/white and white/orange)

With all that in mind i can see why it took a while to sort.

I did voltage tests and also the good old fashioned 'twist one end together and test all the combinations for continuity' trick!!

Very helpful posts though everyone thanks a lot.

Eddie