I ran into a weird one today. House I'm working at has phone service from cable company. Everything is wired with quad wire, but it's mostly all in good shape. Only a single line, so nothing on yellow/black anyway. About 4-500 feet from the house is the barn. There is an existing buried phone cable from the house to the barn, standard sort of direct burial, metal rodent shield, icky pic sort of thing. Not twisted pair, but normal quad colors.

The barn feed was already tied into the house wiring using the yellow/black wires. In my brain this meant there was probably a fault on the red/green. I slap up a couple cheap wall phones in the barn and horse arena and they seem to work fine. (To be fair, I heard dial tone and called it a win, because I was too busy with 100 other things going on. Well, I had some dead time tonight when I was there and called a friend to kill some time while waiting on some stuff to show up. Cell service is lousy at this house, and since I'm friends with the owner, I jump on the house phone. Then I hear it. That godawful sound of an unbalanced line. Argh.

So, I poke around. Clip the scotchloks off the line going to the barns and what do you know, nice and quiet line. OK, so there's some issue with a buried cable that's who knows how old... shocking.

So I try using the red/green pair.

Same result.

Try weird combinations, red/yellow, red/black, green/yellow, green/black

Same result. Noise.

I don't know what the heck possessed me to try the next thing....

I parallel the wires. Inside the house I hook ring to Red+yellow and tip to Green+black..... The far end is still only connected to the yellow/black at this point.

The line is DEAD SILENT. Not dead, it works perfectly and has no noise.

I'm stumped. It works, hooray. I'd love to know why.

Cable modems (EMTAs) provide a combination of outputs for phone lines. On the basic two-line versions, the first jack is an RJ14, wired for up to two lines within the unit itself. The second jack is an RJ11 for only the second line.

On four-line units, the first jack is an RJ14 for lines 1/2, the second jack is an RJ11 for line 2 only, the third jack is an RJ14 for lines 3/4 and the fourth jack is an RJ11 for line 4 only.

It's very easy for the second pair to somehow get crossed with the first pair when tying into existing wiring. If the second line was live, you'd get "double dial tone", which is easy to identify and correct. If only the first line port is live, the second port (although inactive) still puts a load on the line comparable to imbalance because it is, well, imbalance. I'm willing to bet that this has something to do with your issue. I see this all the time when people use 4/C line cords to feed from the EMTA into existing wiring. Hopefully, this will give you some insight.

Following what Ed said, I'm wondering if just putting a termination, like 600 ohm resister across the pair on the unused pair would have accomplished the same this.

I was careful to not cross the two outputs from the cable modem. It is connected to a Jack with a normal silver satin cord, but inside the Jack, I only wired the first pair (red/green) to the jack.

This monkey business I did was on the cable leading to the barn.

If I disconnected this cable leading to the barn, the problem went away. But we really want the phones in the barns to work for safety reasons. It is an equine facility with poor to no cell service.

I don’t understand why I’d have noise on the line using any combination of conductors on this buried cable, but the noise goes away when I parallel the conductors. I’ve always had a heck of a time posting pictures to the forums, but if I can, I will.

On the house end, I connected the red and yellow wires of the buried cable to the red of the house wiring, and the green and black of the buried cable to the green of the house wiring. At the barn end the barns wiring is connected only to the yellow and black of the buried cable. It makes no sense to me why this would work, but here we are.

Ever since photobucket went to crap I’ve never had any luck posting images. If any other mod knows how to fix that so it displays, be my guest.

Induction? From power or another source.

First. Thank you, Professor.

Bill, I don’t know. I don’t think there’s any AC anywhere near that cable, but who knows. It’s probably been in the ground 30-40 years.

My guess then is that the second pair is providing enough capacitance to 'absorb' any induced hum. This would often happen on paging adapters that were connected directly to CO lines. What we did in these instances was to connect a 'half ringer' module from a standard NID across the line to eliminate the hum. Keep in mind that inductive hum can come from the tiniest of stray voltages, especially when a line runs over long lengths of quad (non-twisted pair) wire. This drop wire is just that, shielded quad. With the sheath not grounded, it picks up just about anything out there like an antenna.
https://i.ebayimg.com/images/i/400465573437-0-1/s-l1000.jpg

Read the conductors with an ohm meter for shorts, opens and grounds.

What does it sound like with the barn inside wires disconnected?

There's leakage between the red and yellow and or leakage between the black and green. Put em' together and there is no place to leak to except themselves.

-Hal

I agree with Hal. I bet if you took a simple VOM meter you'd see faults in that buried cable. Are the NID's one each end of this OPE properly grounded and is shield on the cable itself properly bonded?

I'd test it, but I'm with Ed.