Phone line not working - no dial tone, weak tone for toner probe 5

[LePivert]

We have wall-mounted (analog) phones in each classroom (I work in a school) meant for emergency calls.

In one room (let's say room X), there is no dial tone.

If I lift the phone in that room off the wall plate and place it on the wall plate in one of the adjoining rooms, it works (dial tone is audible).

If I take the phones from one of the other rooms (that work in those rooms - i.e. have dial tone) and place them on the wall plate in room X, no dial tone.

I've done this over and over again and the result is consistent.

So, I took our toner probe and compared connections.

In the rooms where there is a dial tone, the tone at the punch down block is strong (loud).

The tone from the line going to room X is audible but weak.

I assume there is some connectivity, but not very good, not good enough to obtain a dial tone.

It looks like it must be the line because neither the wall plate or the punched down wires look damaged or put of place.

What can I do next?

 

[trvlr1]

Follow the line along to all cross connects. If you have a Butt set, clip on to the connections and see where the dial tone "disappears". Make sure at that point the cable is good and there are no bits of broken cable in the connections that might interfere with the signal, go to the previous cross connect and do the same there.
If this does not fix the issue, it may well be the cable or the actual jack on the wall that has gone bad. Can you at least put a temp jack on the end of the cable to see if the issue goes away?

 

[edfair]

In a similar situation I opened up a cable in mid run to check the voltage between the 2 wires and compare to what was supplied using a VOM.



Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[jrgood0852]

Sounds like you are only getting half of the pair (one wire). Try a different pair and bet it works, unless that whole cable is damaged.

 

[LePivert]

Thanks to all for the pointers.

trvlr1:

1. I do not have a butt set, unfortunately.
2. I tested the tone at the first punch down panel coming from the room. The tone was already quite weak there.

I'm more of a data network person so I'm not entirely sure what "cross connects" are but I think that's when you place "jumpers" from one panel to another or to a demarc where the line comes into the building (?).

3. I can see if we have any spare jacks around.

Ed Fair:

4. VOM? volt meter? I think our maintenance team would have that but I would hesitate to cut open the cable (???).

jrgood0852

5. I'm not sure how I'd swap the wires. I'll try to take a picture of the wiring on the panel - maybe that would help you advise me.

I've been assigned a lot of things to do this start of the school year so if I don't get back ready away, it's not that I have forgotten about you -thanks guys once again.

 

[Splic3d]

A smashed/pinched cable will give the same kind of results as well. The cable can be pinched to the point of not giving a total short. A total short will usually kill the tone.

http://www.i3techgroup.com

If its not working, get a bigger hammer!

Avaya/Nortel/NEC/Asterisk/Access Control/CCTV/DSX/Acti/UCx

 

[edfair]

VOM=volt-ohm+ammeter of some value.

Does the cable have 4 wires with only 2 used? (possibly red, green, black, and yellow)
If so, you could disconnect everything on the phone end and use one of the spares as one lead to test the continuity of the 2 active wires in turn.

Agreed on the broken connection, either wire broken or punchdown corroded. Toner will pick up signal from adjacent wires although volume will be decreased.

Phone is a current driven device using about 48 volts to push through the signal. With the phone on-hook there should be the 48v dc on the red/green with the positive on green IIRC.

Radio Shack used to have a phone jack tester. Plug it in and get red, green, or nothing. Red was reversed wiring, green OK, and nothing if things are not connected.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[TouchToneTommy]

You have a toner and a probe. Sending tone only helps you identify the cable in question, it doesn't prove continuity of the conductors. However, if you connect the tone at one end, find it with your probe at the other end, and then short the conductors together, it will prove continuity by stopping the tone. If the tone only changes a little, or even gets louder when the conductors are shorted together, one of them is open.

I would start by replacing the jack that the phone is hanging on.

 

[LePivert]

I am leaning toward the hypothesis of the damaged cable.

Here's why.

Last year, in the context of our Emergency Plan, we tested all the phones. Actually called front desk from each one so the recoptionist could confirm extension numbers as well.

So at some point last year (honestly don't remember which month), ALL the phones were working.

A couple weeks ago, some guys ran more cable and used the same run. At some points they had to remove the conduit and replace it with some larger because of the additional cables (data cables).

It is very plausible that a wire could have been crushed or otherwise damaged.

I can still try another jack. Most likely we'll run another cable anyway.

Come to think of it... people from the company will be coming back one of these days so I think I'll ask them to test it - with something more sophisticated than what we have.

 

[SYQUEST]

Why not just get a real phone person to repair it, if you are not qualified or understand telephony!

....JIM....

 

[Mountainbear]

The cable is damage somewhere between the jack and where the tone gets loud. As mentioned you can try switching pairs or just replace that section on cable. The other option is if a classroom is nearby you could steal the second pair from that jack.

 

[jrgood0852]

Sorry, SYQUEST, but we are here to help each other. We all have different strengths and weeknesses. Not being fair.

 

[Ekster]

Never understand why people try to trace faults on a pair of wires with a tone set! All it will do is identify the pair, if you want more detailed diagnostic information learn to use a multi-meter. Preferably an analogue one with an A/B reversal button like a SA9083 -

http://www.jmwlimited.co.uk/Tester_SA9083_Linesmans_Multimeter.html

+++ Divide By Cucumber Error. Please Reinstall Universe And Reboot +++

 

[Ekster]

Earth Contacts:
Set the rotary selector switch to Earth B. Connect leads across
the pair and to earth, any movement of the meter needle
indicates an earth is present on the 'B' leg. Press the B-A
change button, any movement of the meter needle indicates an
earth is present on the 'A' leg.

Insulation Resistance:
Set the rotary selector switch to Ohms x 100. Connect leads
across the pair. Take a reading from the top scale. Any
movement of the meter needle indicates low insulation
resistance. Sometimes a polarised (rectified) fault occurs where
a reading can be obtained in one direction only therefore it is
important to press the B-A change button to check the other
direction.

Loops/Conductor Resistance:
Set the rotary selector switch to Ohms Loop. Connect leads
across the pair, a loop or short circuit can be identified by a
deflection of the meter needle. A loop or short circuit can also
be identified by a full scale deflection when using the Ohms x
100 range

Disconnections:
If a disconnection is suspected (i.e. not picking up expected line
conditions) to establish if the 'A' or 'B' leg is disconnected follow
the procedure given below:
Set the rotary selector switch to Ohms x 100. Connect the red
lead to the 'A' leg and the black lead to earth. Press the B-A
change button and note the amount of meter needle deflection.
Connect the red lead to the 'B' leg and press the B-A change
button noting the amount of meter needle deflection. Compare
the two deflections, if there is any noticable difference then the
leg with the smallest amount of deflection may not be going as
far as the other leg.

Ballistic Test:
This test is used when testing into a customers premises and
can identify either a 700 type capacitor, an N.T.E. or an L.J.U.
Set the rotary selector switch to Ohms x 100. Connect the red
and black leads across the pair to be tested. Press the B-A
change button.
1. If the meter needle deflects to about half full scale and
returns quickly you are testing into a 700 type capacitor.
2. If the meter needle deflects only slightly and returns slowly
you are testing into an N.T.E. or L.J.U.

+++ Divide By Cucumber Error. Please Reinstall Universe And Reboot +++

 

[jrgood0852]

Thanks for the detail, Ekster....wow!

Always look out for the other guy because one day it will be you!

 

[randybear28]

How do you replace conduit without redoing all the wiring? Is the phone wiring OUTSIDE the conduit? Are there splices in the cat3 in the cabling runs?

 

[randybear28]

If that is the case, cat3 outside the conduit, then forget trying to trouble shoot the existing lines and just run new lines through the conduit. Hopefully there's string still left in the conduit.

 

[jrgood0852]

Hopefully there's string still left in the conduit."..................

Hence my signature.......

Always look out for the next guy because it may be you!

 

[SYQUEST]

"Hopefully there's string still left in the conduit."..................

Tell that to the electricians that do LV, most don't care, and that would be the last thing they would do!

....JIM....

 

[jrgood0852]

Totally agree, Jim. Only us real LV guys look out for each other. Was always thus. Thanks.

Always look out for the next guy because it may be you!