I am having sporadic problems with DSL. I have established that the source
of problem is the phone line, because I have connected two different laptops
directly to the AT&T outside box in order to bypass the house wiring
completely and the problem persists with both PCs.



I called the AT&T customer service and the technician confirmed that the
line was unbalanced (squirrels chewing on the wiring). To solve the problem,
he just swapped the old pair with an unused one. The situation has now
improved somewhat but still the reliability is not 100%.



To satisfy my curiosity, I loaded the phone line (again bypassing the house
wiring) with one 2Kohm resistor. The measured loop current is ~15mA (well
below the range of the max. REN load). I was expecting to find a symmetrical
voltage change at the TIP (RED) and the RING (GREEN). To my surprise the
TIP voltage dropped from 0V to –19V and the RING voltage went up from –51.5V
to –49.30V. Obviously the line is totally unbalanced.



Is my assumption correct that the line should be at least DC balanced when
referred to ground?



TIA,

Gene



================================================== ====================================
"Those who cannot change their minds cannot change anything." - - - George
Bernard Shaw
---------------------------------------------------------------------------------------------------------------------------------------------------
"Scientists study the world as it is; engineers create the world that has
never been." - - - Theodore von Kármán
---------------------------------------------------------------------------------------------------------------------------------------------------

On 2/1/08 9:07 PM, in article
, "EpsilonRho"
wrote:

I am having sporadic problems with DSL. I have established that the source
of problem is the phone line, because I have connected two different laptops
directly to the AT&T outside box in order to bypass the house wiring
completely and the problem persists with both PCs.

What kind of problems? Do you hear it on the line?




I called the AT&T customer service and the technician confirmed that the
line was unbalanced (squirrels chewing on the wiring). To solve the problem,
he just swapped the old pair with an unused one. The situation has now
improved somewhat but still the reliability is not 100%.



To satisfy my curiosity, I loaded the phone line (again bypassing the house
wiring) with one 2Kohm resistor. The measured loop current is ~15mA (well
below the range of the max. REN load).

REN is not a factor in loop current considerations, only the phone (430 Ohms
DC) and the loop resistance to the serving switch or Mux line card are.

I was expecting to find a symmetrical
voltage change at the TIP (RED) and the RING (GREEN). To my surprise the
TIP voltage dropped from 0V to –19V and the RING voltage went up from –51.5V
to –49.30V. Obviously the line is totally unbalanced.

Without knowledge of the serving arrangement and signals that may be
present, neither the readings nor the conclusion are not of any value.




Is my assumption correct that the line should be at least DC balanced when
referred to ground?

No.

It should be balanced for transmission, but not necessarily for DC.

Loop current and transmission are both with respect to the Ring and Tip, NOT
to ground. I don't have your loop specs, but it may be you are being served
by a Pair-gain Mux, in which case the 2000 Ohms you tested with is much too
high.






TIA,

Gene



================================================== ============================
========
"Those who cannot change their minds cannot change anything." - - - George
Bernard Shaw
------------------------------------------------------------------------------
---------------------------------------------------------------------
"Scientists study the world as it is; engineers create the world that has
never been." - - - Theodore von Kármán
------------------------------------------------------------------------------
---------------------------------------------------------------------

Thank you for reply.

What kind of problems? Do you hear it on the line?

The ADSL modem looses lock and the connection to Internet is lost from a few
seconds to a few minutes (HF burst noise?), not a very good thing when one
is
talking on VoIP. I tried with two different modems, bypassing the house
wiring, both behave in the same way. BTW, if it is noise, it must be above
the cut-off frequency of the voice bandwith, because I cannot hear it. Any
lead where I could find on the Web the electrical specification for a
typical phone-line. I tried to google with no results.

TIA,
Gene

EpsilonRho wrote:

I am having sporadic problems with DSL. I have established that the source
of problem is the phone line, because I have connected two different laptops
directly to the AT&T outside box in order to bypass the house wiring
completely and the problem persists with both PCs.



I called the AT&T customer service and the technician confirmed that the
line was unbalanced (squirrels chewing on the wiring). To solve the problem,
he just swapped the old pair with an unused one. The situation has now
improved somewhat but still the reliability is not 100%.



To satisfy my curiosity, I loaded the phone line (again bypassing the house
wiring) with one 2Kohm resistor. The measured loop current is ~15mA (well
below the range of the max. REN load). I was expecting to find a symmetrical
voltage change at the TIP (RED) and the RING (GREEN). To my surprise the
TIP voltage dropped from 0V to � and the RING voltage went up from �5V
to �30V. Obviously the line is totally unbalanced.



Is my assumption correct that the line should be at least DC balanced when
referred to ground?



TIA,

Gene



================================================= =====================================
"Those who cannot change their minds cannot change anything." - - - George
Bernard Shaw
---------------------------------------------------------------------------------------------------------------------------------------------------
"Scientists study the world as it is; engineers create the world that has
never been." - - - Theodore von K醨m醤
---------------------------------------------------------------------------------------------------------------------------------------------------









I had some trouble with my ATT DSL which stemmed from 1) Need for
filters on all phone jacks in the house. ATT put a master filter outside
in the NIC box to isolate all the old wiring. This helps. 2) I am at the
16,000 + distabce from the CO so my line is a compromise. 3) Some of my
old wiring was loose and shorting where it left the NIC. Still not 100%
perfect but more reliable.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P

EpsilonRho wrote:

I am having sporadic problems with DSL. I have established that the source
of problem is the phone line, because I have connected two different laptops
directly to the AT&T outside box in order to bypass the house wiring
completely and the problem persists with both PCs.



I called the AT&T customer service and the technician confirmed that the
line was unbalanced (squirrels chewing on the wiring). To solve the problem,
he just swapped the old pair with an unused one. The situation has now
improved somewhat but still the reliability is not 100%.



To satisfy my curiosity, I loaded the phone line (again bypassing the house
wiring) with one 2Kohm resistor. The measured loop current is ~15mA (well
below the range of the max. REN load). I was expecting to find a symmetrical
voltage change at the TIP (RED) and the RING (GREEN). To my surprise the
TIP voltage dropped from 0V to � and the RING voltage went up from �5V
to �30V. Obviously the line is totally unbalanced.



Is my assumption correct that the line should be at least DC balanced when
referred to ground?



TIA,

Gene



================================================= =====================================
"Those who cannot change their minds cannot change anything." - - - George
Bernard Shaw
---------------------------------------------------------------------------------------------------------------------------------------------------
"Scientists study the world as it is; engineers create the world that has
never been." - - - Theodore von K醨m醤
---------------------------------------------------------------------------------------------------------------------------------------------------









I had some trouble with my ATT DSL which stemmed from 1) Need for
filters on all phone jacks in the house. ATT put a master filter outside
in the NIC box to isolate all the old wiring. This helps. 2) I am at the
16,000 + distabce from the CO so my line is a compromise. 3) Some of my
old wiring was loose and shorting where it left the NIC. Still not 100%
perfect but more reliable.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P

On Sat, 2 Feb 2008 15:10:00 -0800, "EpsilonRho" wrote:

:Thank you for reply.
:
:What kind of problems? Do you hear it on the line?
:
:The ADSL modem looses lock and the connection to Internet is lost from a few
:seconds to a few minutes (HF burst noise?), not a very good thing when one
:is
:talking on VoIP. I tried with two different modems, bypassing the house
:wiring, both behave in the same way. BTW, if it is noise, it must be above
:the cut-off frequency of the voice bandwith, because I cannot hear it. Any
:lead where I could find on the Web the electrical specification for a
:typical phone-line. I tried to google with no results.
:
:TIA,
:Gene
:

The typical POTS line dc condition is simply the battery feed retard which is
usually a 200ohm + 200ohm balanced high Z transformer.

Essentially, behind one of the 200ohm windings will be -52V dc and behind the
other 200ohm winding will be +ve. Remember that the +ve side of the exchange
battery is connected directly to ETH. So, at the customer premises the +ve leg
will have 1/2 the line loop resistance plus the 200ohm retard to ETH and the -ve
leg will have a similar line resistance + the 200ohm retard to -52V.

Your ADSL modem must be connected on the raw line connection and each telephone
device which relies upon the same POTS line must have a filter (unless you use a
whole-of-premises filter). If you can get your modem connected directly to the
line at the incoming connnection point and throw off all other telephone
instruments inside the house you will be able to determine if your internal
wiring is the cause of the problem.

The typical POTS line dc condition is simply the battery feed retard which
is
usually a 200ohm + 200ohm balanced high Z transformer.

Essentially, behind one of the 200ohm windings will be -52V dc and behind
the
other 200ohm winding will be +ve. Remember that the +ve side of the
exchange
battery is connected directly to ETH. So, at the customer premises the +ve
leg
will have 1/2 the line loop resistance plus the 200ohm retard to ETH and
the -ve
leg will have a similar line resistance + the 200ohm retard to -52V.

Thanks for this info. What you are saying is that the DC resistance and the
AC impedence should be the same on TIP and RING.

Your ADSL modem must be connected on the raw line connection and each
telephone
device which relies upon the same POTS line must have a filter (unless you
use a
whole-of-premises filter). If you can get your modem connected directly to
the
line at the incoming connnection point and throw off all other telephone
instruments inside the house you will be able to determine if your internal
wiring is the cause of the problem.

As I pointed out before, the house wiring is totally excluded from the test
I performed, because I plugged the modem directly into the AT&T outside box,
after having disconnected the house wiring from the line. After some further
investigation, I think I found the problem. I have establish that when
everything is working normally the resistance (DC) of TIP is 2,166 Ohm and
the RING is 2,179 Ohm. But, when I am having ADSL problems, the TIP
resistance drops to 146 Ohm. I am speculating that somewhere along the line,
the TIP wire insulator is damaged and it shorts to ground, disrupting in
this way the balance of the line. Because the phone lines to my house are on
poles, I suspect that small changes due to the atmospheric conditions (wind,
temperature, rain, etc.) are creating these sporadic shorts.
I called AT&T and they agree to re-send a technician.

Thank you all.
Gene

On Mon, 04 Feb 2008 06:55:45 GMT, "EpsilonRho" wrote:

:
:The typical POTS line dc condition is simply the battery feed retard which
:is
:usually a 200ohm + 200ohm balanced high Z transformer.
:
:Essentially, behind one of the 200ohm windings will be -52V dc and behind
:the
:other 200ohm winding will be +ve. Remember that the +ve side of the
:exchange
:battery is connected directly to ETH. So, at the customer premises the +ve
:leg
:will have 1/2 the line loop resistance plus the 200ohm retard to ETH and
:the -ve
:leg will have a similar line resistance + the 200ohm retard to -52V.
:
:Thanks for this info. What you are saying is that the DC resistance and the
:AC impedence should be the same on TIP and RING.


Assuming your line has been constructed using a uniform cable pair and all
intermediate joints are properly made it will have equal resistance in each leg
between the exchange and the demarcation point at your premises. AC impedance of
the line is not an issue as long as the dc conditions test ok.

The telco will be able to determine if the line is ok for telephone service
using their automatic line test. They will also be able to determine if the
cable pair is capable of acceptable DSL operation.

Telephone line standards where you are should be the same as in Australia and
certain test conditions should be applied to determine the suitability of the
line for both POTS and DSL service.

For example, this test instrument specification shows typical tests which should
be applied to a copper pair to assess its suitability for service.
http://www.teletech.com.au/products/tx120.html

Problem solved. The AT&T technician changed the pair arriving to my house
with some unused ones (this is the second time) and now the impedance of TIP
& RING is virtually the same and not changing. No interruption has occurred
in 24 hours! The conclusion of the story is that the impedance of the line
should be the same for the positive and the negative, if it is not the case
the common mode rejection is greatly degraded making the line susceptible to
external disturbances.
Thank you again to you all,
Gene

On Tue, 5 Feb 2008 17:00:37 -0800, "EpsilonRho" wrote:

:Problem solved. The AT&T technician changed the pair arriving to my house
:with some unused ones (this is the second time) and now the impedance of TIP
:& RING is virtually the same and not changing. No interruption has occurred
:in 24 hours! The conclusion of the story is that the impedance of the line
:should be the same for the positive and the negative, if it is not the case
:the common mode rejection is greatly degraded making the line susceptible to
:external disturbances.
:Thank you again to you all,
:Gene
:
:

Glad to know the problem is solved. It seems that the tech/liney just took pot
luck on both occasions and grabbed whatever free pair was available in the
cable. The first time he struck out and the second time he got lucky. I'll bet
he didn't log that first pair he tried (or your original pair either) as
'faulty', so the next customer who experiences similar symptoms will have an
even greater chance of getting a dud pair. Bloody, lineys, - duh.. what's a line
test?

As far as telephone lines are concerned you don't say that "each leg of the line
is the same impedance". It is simply a balanced twisted pair which means that
providing that no leakage, insulation or earth faults exist on either leg then
the DC resistance of each leg will be exactly equal. The pair should then
perform in accordance with appropriate standards, barring other problems of
course, (such as a double jumper connecting your pair to another pair which is
unterminated) It might still be balanced in a DC sense but that stub pair
creates all sorts of reflections. That is why it is important to do a proper
test on each pair that is to be used for DSL.

On 2/7/08 2:10 AM, in article ,
"Ross Herbert" wrote:

On Tue, 5 Feb 2008 17:00:37 -0800, "EpsilonRho" wrote:

:Problem solved. The AT&T technician changed the pair arriving to my house
:with some unused ones (this is the second time) and now the impedance of TIP
:& RING is virtually the same and not changing. No interruption has occurred
:in 24 hours! The conclusion of the story is that the impedance of the line
:should be the same for the positive and the negative, if it is not the case
:the common mode rejection is greatly degraded making the line susceptible to
:external disturbances.
:Thank you again to you all,
:Gene
:
:

Glad to know the problem is solved. It seems that the tech/liney just took pot
luck on both occasions and grabbed whatever free pair was available in the
cable.

The repairman does not just "grab" whatever free pair is available. He
obtains a new cable/pair assignment from the cable assignment group, who
will use whatever pair is unassigned and zoned for the location/service that
was ordered. So what's the problem?

The first time he struck out and the second time he got lucky.

What does your cynical view do to explain the situation?

I'll bet
he didn't log that first pair he tried (or your original pair either) as
'faulty', so the next customer who experiences similar symptoms will have an
even greater chance of getting a dud pair. Bloody, lineys, - duh.. what's a
line test?

HE didn't log it, but HE did report the trouble to the assignment office
that gave him the new pair. They will flag it as defective and initiate a
trouble ticket for a cable repairman to fix. They do it, because if one
pair is in trouble, there may be a condition that will spread to other
pairs.


As far as telephone lines are concerned you don't say that "each leg of the
line
is the same impedance". It is simply a balanced twisted pair which means that
providing that no leakage, insulation or earth faults exist on either leg then
the DC resistance of each leg will be exactly equal. The pair should then
perform in accordance with appropriate standards, barring other problems of
course, (such as a double jumper connecting your pair to another pair which is
unterminated) It might still be balanced in a DC sense but that stub pair
creates all sorts of reflections. That is why it is important to do a proper
test on each pair that is to be used for DSL.

Don Bowey wrote:

HE didn't log it, but HE did report the trouble to the assignment office
that gave him the new pair. They will flag it as defective and initiate a
trouble ticket for a cable repairman to fix. They do it, because if one
pair is in trouble, there may be a condition that will spread to other
pairs.


Like when lightning hit my place near Eustis, Fl. about 10 years ago.
It was a direct strike to both the electrical and telephone service. It
vaporized the pair to the highway, the card, and rendered the pair from
that card to the CO unusable. It took several repairs before the line
was usable again.

It really ****ed me off when calling repair service each time. The
first two times I had to drive 10 miles into town, because all of the
phones on my street were dead (Five homes). I was having to scream, and
repeat myself between the loudest bursts to be heard over the static,
yet the woman said she didn't really think there was anything wrong, for
the next several calls.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

On 2/7/08 10:29 AM, in article , "Michael A.
Terrell" wrote:

Don Bowey wrote:

HE didn't log it, but HE did report the trouble to the assignment office
that gave him the new pair. They will flag it as defective and initiate a
trouble ticket for a cable repairman to fix. They do it, because if one
pair is in trouble, there may be a condition that will spread to other
pairs.


Like when lightning hit my place near Eustis, Fl. about 10 years ago.
It was a direct strike to both the electrical and telephone service. It
vaporized the pair to the highway, the card, and rendered the pair from
that card to the CO unusable. It took several repairs before the line
was usable again.

It really ****ed me off when calling repair service each time. The
first two times I had to drive 10 miles into town, because all of the
phones on my street were dead (Five homes). I was having to scream, and
repeat myself between the loudest bursts to be heard over the static,
yet the woman said she didn't really think there was anything wrong, for
the next several calls.


That is a bad experience. Dealing with the repair service "screeners" can
be a chore, but usually it's better than that. I've had lots of repair
service experience dealing with the screeners and the public. At one time,
among other things, I managed the after-hours repair service bureau for
Oregon and anything my supervisors or their people couldn't resolve, came to
me.

On Thu, 07 Feb 2008 08:19:13 -0800, Don Bowey wrote:

:On 2/7/08 2:10 AM, in article ,
:"Ross Herbert" wrote:
:
: Glad to know the problem is solved. It seems that the tech/liney just took
pot
: luck on both occasions and grabbed whatever free pair was available in the
: cable.
:
:The repairman does not just "grab" whatever free pair is available. He
btains a new cable/pair assignment from the cable assignment group, who
:will use whatever pair is unassigned and zoned for the location/service that
:was ordered. So what's the problem?

It depends on whether the cable pair which was swapped was in a main cable from
the exchange or simply a local drop cable feeding a particular street from a sub
distribution point (pillar). Also, depending upon the methods used to correctly
identify and amend cable pair records, these can become horribly out of whack
over many years of accumulated non-report and/or repair and the faulty pairs are
left until a major upgrade is required.

Back in the late 80's early 90's as much as 30% of manually maintained cable
pair records were estimated to be incorrect in the major cities of Australia,
and our design group was charged with producing an automated cable pair check
and logging system which was used to thoroughly log every main frame and cable
pillar record in the country. The system proved the estimates were in fact
correct and the Switch Number Identifier was able to carry out the project in
only 2 years. It was estimated that a manual jumper trace and record would have
taken about 1000 man-years to do the same thing.

If what you say is true then how come the first "assigned" pair was faulty? One
would assume that all faulty pairs would have been already logged and the cable
assigner would know what pairs NOT to assign. This procedure obviously didn't
happen. These days many telco's who also have responsibility for residential
cable networks don't bother too much with accurate record keeping as far as
local drop cables from street pillars are concerned, and liney's are known to
take short cuts to save time and trouble if they have a heavy workload. If they
have been assigned a pair which proves faulty they generally just pick another
local drop pair and simply check to see if it is already jumpered. If
unjumpered, they grab it without more testing than a check with their butt to
see if it sounds bad (hum or noise), and then if they feel inclined, tell the
cable assigner - generally too much troble and paperwork. Anyway, failure to
report the pair faulty (when subsequently discovered months down the track) is
just seen as an oversight in a busy day and anyway, the next liney will find it
and report it - but usually only after it has been re-assigned and another
customer complains.

:
: The first time he struck out and the second time he got lucky.
:
:What does your cynical view do to explain the situation?

Experience, see above.

:
: I'll bet
: he didn't log that first pair he tried (or your original pair either) as
: 'faulty', so the next customer who experiences similar symptoms will have an
: even greater chance of getting a dud pair. Bloody, lineys, - duh.. what's a
: line test?
:
:HE didn't log it, but HE did report the trouble to the assignment office
:that gave him the new pair. They will flag it as defective and initiate a
:trouble ticket for a cable repairman to fix. They do it, because if one
air is in trouble, there may be a condition that will spread to other
airs.

You know for a fact that he did report it do you? Then what happened in the case
of the first pair assigned to fix the OP's problem? One would assume that if the
cable records were kept up to date then he wouldn't have been assigned a known
faulty pair in the first place. Going by the non-workability of the initial pair
assigned to the OP's service, and then getting another faulty pair assigned at
the first attempt to fix the problem, I would say that the local cable records
are in a woeful state. It is obvious that there are at least 2 local drop pairs
to the OP's area which are faulty, so there is a very good chance that there are
several more in that cable as well. Until all good pairs in the cable are in use
the telco won't bother to upgrade or repair the faulty pairs - it costs too much
to just fix one or two pairs so they wait till they absolutely have to do
something - I know how they work.

On 2/7/08 6:56 PM, in article ,
"Ross Herbert" wrote:

On Thu, 07 Feb 2008 08:19:13 -0800, Don Bowey wrote:

:On 2/7/08 2:10 AM, in article ,
:"Ross Herbert" wrote:
:
: Glad to know the problem is solved. It seems that the tech/liney just took
pot
: luck on both occasions and grabbed whatever free pair was available in the
: cable.
:
:The repairman does not just "grab" whatever free pair is available. He
btains a new cable/pair assignment from the cable assignment group, who
:will use whatever pair is unassigned and zoned for the location/service that
:was ordered. So what's the problem?

It depends on whether the cable pair which was swapped was in a main cable
from
the exchange or simply a local drop cable feeding a particular street from a
sub
distribution point (pillar). Also, depending upon the methods used to
correctly
identify and amend cable pair records, these can become horribly out of whack
over many years of accumulated non-report and/or repair and the faulty pairs
are
left until a major upgrade is required.

Back in the late 80's early 90's as much as 30% of manually maintained cable
pair records were estimated to be incorrect in the major cities of Australia,
and our design group was charged with producing an automated cable pair check
and logging system which was used to thoroughly log every main frame and cable
pillar record in the country. The system proved the estimates were in fact
correct and the Switch Number Identifier was able to carry out the project in
only 2 years. It was estimated that a manual jumper trace and record would
have
taken about 1000 man-years to do the same thing.

If what you say is true then how come the first "assigned" pair was faulty?
One
would assume that all faulty pairs would have been already logged and the
cable
assigner would know what pairs NOT to assign. This procedure obviously didn't
happen. These days many telco's who also have responsibility for residential
cable networks don't bother too much with accurate record keeping as far as
local drop cables from street pillars are concerned, and liney's are known to
take short cuts to save time and trouble if they have a heavy workload. If
they
have been assigned a pair which proves faulty they generally just pick another
local drop pair and simply check to see if it is already jumpered. If
unjumpered, they grab it without more testing than a check with their butt to
see if it sounds bad (hum or noise), and then if they feel inclined, tell the
cable assigner - generally too much troble and paperwork. Anyway, failure to
report the pair faulty (when subsequently discovered months down the track) is
just seen as an oversight in a busy day and anyway, the next liney will find
it
and report it - but usually only after it has been re-assigned and another
customer complains.

:
: The first time he struck out and the second time he got lucky.
:
:What does your cynical view do to explain the situation?

Experience, see above.

:
: I'll bet
: he didn't log that first pair he tried (or your original pair either) as
: 'faulty', so the next customer who experiences similar symptoms will have
an
: even greater chance of getting a dud pair. Bloody, lineys, - duh.. what's a
: line test?
:
:HE didn't log it, but HE did report the trouble to the assignment office
:that gave him the new pair. They will flag it as defective and initiate a
:trouble ticket for a cable repairman to fix. They do it, because if one
air is in trouble, there may be a condition that will spread to other
airs.

You know for a fact that he did report it do you? Then what happened in the
case
of the first pair assigned to fix the OP's problem? One would assume that if
the
cable records were kept up to date then he wouldn't have been assigned a known
faulty pair in the first place.

Everything is "good" until it fails. Perhaps it was the first pair damaged
by a gopher or a heavy rain.

Going by the non-workability of the initial pair
assigned to the OP's service, and then getting another faulty pair assigned at
the first attempt to fix the problem, I would say that the local cable records
are in a woeful state.

No, it doesn't mean the assignment records were faulty. It means the
assignment people weren't aware of a general cable fault at that time.

It is obvious that there are at least 2 local drop pairs to the OP's area
which are faulty, so there is a very good chance that there are several more
in that cable as well.

Are you changing the topic from distribution cable pairs to drop pairs?
It's apples and oranges. Drops are not "cable pairs" and are not assigned
by the assignment center.

Until all good pairs in the cable are in use
the telco won't bother to upgrade or repair the faulty pairs - it costs too
much to just fix one or two pairs so they wait till they absolutely have to do
something - I know how they work.

You do not "know how it works" except perhaps in a very narrow area.
Finding two bad pairs in a localized area of a distribution cable is cause
to find and repair the cause(s).

On Thu, 07 Feb 2008 20:41:56 -0800, Don Bowey wrote:

:
:Everything is "good" until it fails. Perhaps it was the first pair damaged
:by a gopher or a heavy rain.

A self evident truth.

A gopher may damage a cable and affect maybe a single pair or two, which is not
so bad, as long as it doesn't rain. However, when water ingress occurs almost
every subscriber in that cable will be affected and repairs are urgently carried
out.

:
:No, it doesn't mean the assignment records were faulty. It means the
:assignment people weren't aware of a general cable fault at that time.

I haven;t even mentioned a "general cable fault".

If the faulty pairs are in a local drop cable, which you admit are not
'assigned' (are local drop faulty pairs even recorded?), then of course the
assignment centre will not be aware of them.

:
: It is obvious that there are at least 2 local drop pairs to the OP's area
: which are faulty, so there is a very good chance that there are several more
: in that cable as well.
:
:Are you changing the topic from distribution cable pairs to drop pairs?
:It's apples and oranges. Drops are not "cable pairs" and are not assigned
:by the assignment center.

On any exchange MDF (copper only in this discussion) there will be Junction
cables (J1, 2 etc) running between exchanges for inter-exchange traffic and
there will be main distribution cables (C1, C2 etc) to carry exchange services
to local subscribers.

The main distribution cables from the exchange MDF travel along major routes and
at various points drop off pair ranges in local distribution pits or cross
connection facilities on street verges - out here we use cable pillars
http://www.export61.com/companydetail.asp?cid=165 but you may use cabinets where
you are. From the pillars, local drop cables (they are referred to as
Distribution Area pillars and are marked DA-xx where xx is the pillar number)
feed the houses from the street via underground cable pits - usually, 1 pit
between two adjacent houses. The customer cable from the pit enters the premises
via a wall mounted network termination enclosure where internal cabling may be
brought to for connection to the line via a network termination device if
required.

Since neither the OP, you, or myself knows which part of the pair between the
exchange and the premises was changed, then it is impossible to say whether the
faulty pair/s used were in the local distribution cable or the main cable. The
main cable pair originally assigned to the OP's premises may have been perfectly
ok but the local drop pair from the street distribution pillar to the premises
may have been the culprit. This might explain why the pair the liney unknowingly
chose a faulty local drop pair. He would naturally record the cross connection
details for the assigned main cable pair but because these local drop pairs are
not assigned by the assignment centre, it is probable they don't know about
them. There is a strong likelihood that there will be more than one unrecorded
unserviceable pair in any local drop cable.

My contention is that when called out to fix the OP's poor DSL connection the
liney selected a spare local drop pair in the local drop pillar/cabinet, ran a
new jumper and then opened the premises feed pit and connected the premises feed
cable to that new pair. Unfortunately, his first selection proved the pair to be
unserviceable and he chose another local pair and re-jumpered in the
pillar/cabinet and re-joined again in the local feed pit. This time his choice
was successful.

:
: Until all good pairs in the cable are in use
: the telco won't bother to upgrade or repair the faulty pairs - it costs too
: much to just fix one or two pairs so they wait till they absolutely have to
do
: something - I know how they work.
:
:You do not "know how it works" except perhaps in a very narrow area.
:Finding two bad pairs in a localized area of a distribution cable is cause
:to find and repair the cause(s).
:
:

Two bad pairs in a local drop cable, where there are no other reports of
problems from existing subscribers, does NOT constitute a reason for a find and
repair callout. The unserviceable pairs may simply be due to poor jointing
technique by a previous liney, but these will in no way affect other working
subscribers.

Local drop pairs which are unserviceable but are not due to a cable damage fault
or water ingress, are simply ignored until such time as there is a strong reason
to go out and fix the faulty pairs. This usually only occurs when the cable is
at full capacity and a new subscriber connection is required. Only then does it
become necessary to find why the unserviceable pairs are faulty and fix them.
So, unserviceable pairs simply lie around waiting to be allocated and
re-allocated and only get repaired when there are no remaining good pairs
available. It is a simple matter of economics.

On 2/8/08 6:41 PM, in article ,
"Ross Herbert" wrote:


(snip)

Sorry you went to the trouble of posting a blog; I didn't read all of it.

You made the good point that the OP did not provide enough detail to enable
us to do more than guess at the facts, which is pointless, so let's let it
go.

On Fri, 08 Feb 2008 20:16:10 -0800, Don Bowey wrote:

:On 2/8/08 6:41 PM, in article ,
:"Ross Herbert" wrote:
:
:
snip)
:
:Sorry you went to the trouble of posting a blog; I didn't read all of it.

I was just making sure you didn't try to infer that I was changing the scope of
the discussion as you did previously so I went to great detail to ensure there
was no confusion. It's a pity I had to do it but sometimes it is difficult to
convey a message which can't be misinterpreted without resorting to kiddie
speak. You chose to call it a blog....

Agreed, lets drop it.


:
:You made the good point that the OP did not provide enough detail to enable
:us to do more than guess at the facts, which is pointless, so let's let it
:go.