BT Wiring Question

[Paul_C]

WB900 thats the line conc yes ?

WB900 is the 1+1 carrier system which was the predecessor to DACS. One subscriber works as for a regular line with normal ringing, D.C. signaling etc. while the second subscriber operates over the carrier system (40kHz carrier sub-to-exch, 64kHz exch-to-sub). Installed from the late 1970's and especially during the 1980's when exchanges were converted to system X, since the latter had no provision for older style party line working.

 

[simonpolly]

WB900 thats the line conc yes ?

WB900 is the 1+1 carrier system which was the predecessor to DACS. One subscriber works as for a regular line with normal ringing, D.C. signaling etc. while the second subscriber operates over the carrier system (40kHz carrier sub-to-exch, 64kHz exch-to-sub). Installed from the late 1970's and especially during the 1980's when exchanges were converted to system X, since the latter had no provision for older style party line working.

Before my time,i`ve heard of the 1+1 but you don`t come across them any more.

 

[Paul_C]

I know WB900 had a battery problem. The direct sub just had a low-pass filter installed to filter out the carrier signals, but the carrier sub unit had a rechargeable battery to run it which was charged when the direct sub was on hook and the full 50V available on the line. If the direct sub line got heavily used, or ended up in a PG condition, the carrier sub could lose service due to the battery not receiving sufficient charge.

I wouldn't imagine there are any still left in service, but you never know - After all, there was an old A/B coinbox in use in a remote part of the Scottish Highlands as late as 1984!

 

[Lectrician]

Yes i have many times HAVE YOU ? you just think you know everything,
Ok clever dick if you disconnect the b1 in the exchange what happens to the b2 ?
And explain this mar 1 .9.02.07

This was what I was wanting Simon to answer

What would happen to B1 if B2 is disconnected?

I have seen DACS's left in place supplying just a single line at times, and this is why I wondered. The last time I saw this was when one of the lines was moved over for ADSL. The other line was left on the DAC's.

What does the kit at the other end of a dacs look like, or is just a different line card or part of the exchange?

I have heard from some others that due to the nature of BT's target driven approach to work load, DAC's where quite often used as a means of installing an addional line quickly on site rather than searching out an additional pair.

 

[Paul_C]

I have seen DACS's left in place supplying just a single line at times, and this is why I wondered. The last time I saw this was when one of the lines was moved over for ADSL. The other line was left on the DAC's.

You can do that at the RU (Remote Unit) end of the link, so long as everything at the EU (Exchange Unit) is set up properly for the single subscriber.

What does the kit at the other end of a dacs look like, or is just a different line card or part of the exchange?

The exchange line cards are the same. DACS is just additional equipment which is jumpered in between the line card and the outgoing line as needed, and consists of the usual arrangement of slot-in cards in racks, although there are two different types in general use in different places which have slightly different arrangements.

The Telspec DACS EU uses pairs of cards (one ALC plus one DLC per pair), with each card pair combining 10 regular lines onto 5 DACS lines, and with up to 8 pairs of cards per rack:

The ECI DACS uses single cards rather than ALC/DLC pairs, with each card combining 4 regular lines onto 2 DACS lines and with up to 15 cards per rack:

 

[simonpolly]

Yes i have many times HAVE YOU ? you just think you know everything,
Ok clever dick if you disconnect the b1 in the exchange what happens to the b2 ?
And explain this mar 1 .9.02.07

This was what I was wanting Simon to answer

What would happen to B1 if B2 is disconnected?

I have seen DACS's left in place supplying just a single line at times, and this is why I wondered. The last time I saw this was when one of the lines was moved over for ADSL. The other line was left on the DAC's.

What does the kit at the other end of a dacs look like, or is just a different line card or part of the exchange?

I have heard from some others that due to the nature of BT's target driven approach to work load, DAC's where quite often used as a means of installing an addional line quickly on site rather than searching out an additional pair.

Its bad practise to leave just the b2 on a dacs,if the Eu exchange unit loses sync with the RU remote unit and there is no b1 connected the b2 will be cut off as it will not re sync,A engineer in a pcp or joint could easily disconnect the pair when re making a joint or removing the dreaded blue beans and the MAR 1.09.02.007 is the mapping for the dacs blocks in the exchange

 

[Paul_C]

Its bad practise to leave just the b2 on a dacs,if the Eu exchange unit loses sync with the RU remote unit and there is no b1 connected the b2 will be cut off as it will not re sync,

For those not familiar with DACS, perhaps it should be pointed out that the connection between the EU and the RU is pretty much like an ISDN line. There are some signaling differences, but it's very similar.

 

[Lectrician]

Its bad practise to leave just the b2 on a dacs,if the Eu exchange unit loses sync with the RU remote unit and there is no b1 connected the b2 will be cut off as it will not re sync,A engineer in a pcp or joint could easily disconnect the pair when re making a joint or removing the dreaded blue beans and the MAR 1.09.02.007 is the mapping for the dacs blocks in the exchange

That makes sence. I am not sure if the ones I saw had the B1 or the B2 left active, I guess it could have been the B1. If an eng pulled a line off a dacs for ADSL, and the line was the B1, would they swap the B2 over to B1 or ditch the dacs completely?

 

[simonpolly]

Its bad practise to leave just the b2 on a dacs,if the Eu exchange unit loses sync with the RU remote unit and there is no b1 connected the b2 will be cut off as it will not re sync,A engineer in a pcp or joint could easily disconnect the pair when re making a joint or removing the dreaded blue beans and the MAR 1.09.02.007 is the mapping for the dacs blocks in the exchange

That makes sence. I am not sure if the ones I saw had the B1 or the B2 left active, I guess it could have been the B1. If an eng pulled a line off a dacs for ADSL, and the line was the B1, would they swap the B2 over to B1 or ditch the dacs completely?

The engineer would pick up a task to remove the b1 to a new set of routing and the b2 should then be taken off the dacs it would then be a del using the original routing the dacs was on and the dacs should be removed

 

[Atilla]

academic - BT no longer deDACS

 

[Lectrician]

Really? I was in a building where a BT eng is doing just that only this morning.

 

[Paul_C]

academic - BT no longer deDACS

Please explain how you think that somebody with basic PSTN service who has been put on DACS can ever get DSL service then, short of having a completely new line installed.

 

[Infidel]

Red care tee hee used to be known as ****ing nightmare when I was a lineman. Infact It wasn't used in our area because it was such a pain.


[/quote]Please explain how you think that somebody with basic PSTN service who has been put on DACS can ever get DSL service then, short of having a completely new line installed.

Free up the pair and dacs someone else who doesn't want dsl.

 

[simonpolly]

academic - BT no longer deDACS

IGNORED AS YOU KNOW NOTHING ABOUT DACS WHICH IS PLAIN FOR EVERYONE TO SEE,I`VE COME TO THE CONCLUSION YOUR A TROLL.

 

[simonpolly]

Red care tee hee used to be known as **** nightmare when I was a lineman. Infact It wasn't used in our area because it was such a pain.

Please explain how you think that somebody with basic PSTN service who has been put on DACS can ever get DSL service then, short of having a completely new line installed.

Free up the pair and dacs someone else who doesn't want dsl.[/quote]

Thats a dacs rearrangement,i`ve done a couple this week.As for redcare its fine as long as you stick to no break recrimping.