Line noise on one pair only


  #1  
Old 04-25-06, 06:38 PM
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Line noise on one pair only

I just had the telephone company install a second line coming into my house. Unfortunately, I now have line noise on this new phone line.

Both lines are extended to the house outlets over a single set of CAT5 cables. I get noise on the second twisted pair, but not on the first.

I have read several items about line cuts, noisy devices, and runs along high-voltage wiring. But since this is all in the same CAT5 run, I am at a loss.

Any ideas out there?
 
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Old 04-25-06, 06:57 PM
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Is the line clean at the NID? Does this or any other line in your home have DSL?
 
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Old 04-26-06, 08:23 AM
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NP at NID, no DSL

The line is ok at the NID. I don't have DSL.
 
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Old 04-26-06, 09:59 AM
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Loose connection at one jack, bad jack, bad phone on 2nd line, etc. It's a process of elimination. Remove one jack at a time from the mix until you find the culprit, etc.

Is there a Cat 5 cable running to each jack, or is a single cable chained from one jack to the next? What about splicing? If there is any, it should be done with Scotchlok connectors, not the "twist and tape" method.

Worst case would be if you had a single, chained cable with damage somewhere inside a wall. Hopefully, that's not the case.

Another option - since you've got 2 spair pairs in that Cat5, try one of the other pairs. If it was a nail or staple hit that damaged the cable, it may not have affected the 3rd and 4th pairs.
 
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Old 04-26-06, 05:57 PM
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Still working at it

Thanks, Bozo.

Here is the setup I have. Two lines from the phone company into my NID. A single CAT5 cable coming from the NID into my house. From inside the house, each pair in the incoming CAT5 cable is connected to the corresponding pair on all the CAT5 runs going to the jacks.

I started working at this today again. First, I went around to each jack and disconnected the second pair from each jack except for the particular jack where I want this line to ring. Then I had noise with BOTH pairs. Go figure. So I went back and started reconnecting all the jacks one-by-one with the second pair of wires. After reconnecting the second pair on a particular jack, the noise on the first pair was eliminated. It seems strange, but that is what happened.

I'm going to start removing the jacks again one-by-one. Maybe I missed something. (BTW, this problem occurs on the second pair on ALL the jacks.)

I figure I have two options after that. First is as you describe and use a third pair. Second option is to go to the basement where the CAT5 comes in from the NID and disconnect the second pair from all but the particular run that I want. Sounds easy, but each set of pairs is twisted together and then connected with a "Dolphin" connector. (I assume that's similar to a Scotchlok.) Just don't want to mess it up.

Thanks again. I'll keep you posted.
 
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Old 04-26-06, 07:36 PM
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I dont know all details.
are you using a two line phone?
or two phones
many times the problem is the cord between the headset and the base or the pacht cord between the wall jack and the base
OR
try this is at the phone company box
make sure that the pairs are making any contact with anything else than the screw is on.
 
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Old 04-26-06, 11:51 PM
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I'm having a hard time visuallizing this but if all the cat 5s home run back to the NID, then thats the place to start your trouble shooting.

You said the line is clean coming in so you must have a phone you can connect to the NID.

Disconnect all your lines at the NID and then connect a pair and test the line. To be safe, take each pair off after testing before you connect the next.

You can probably do all the testing right from the NID but if the noise doesn't come back, start over - connect a pair, then go to the jack end to test.

My guess is a staple in the wire somewhere. It almost sounds like a pair cross rather than a high resistant short. It could be jack or cord problem.
 
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Old 05-07-06, 09:32 PM
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I lean toward what mjd2k hit on.. a staple somewhere in the I/W.. process of elimination, test each I/W one at a time.. when you find the bad one, switch pairs in that cable...
 
 

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