DSL problem

[Mikepier]

Trying to troubleshoot what I thought was a basic problem. A DSL modem installed in a construction trailer not working. There is a 6 pair outdoor phone cable feeding the trailer from the main building. 5 phones work perfectly fine in the trailer. For some reason I can't get the DSL "happy" light to light up on the modem in the trailer. I tested the modem inside the main building just before it leaves the building and it worked fine. I swapped pairs on the outdoor cable, but no help. I know distance is not an issue because I tested that too. I "looped" back the DSL line back down to where it comes in main telephone room ( basically doubling the distance) and it works fine. So I'm thinking this is more of an inteference issue. Any ideas where to start? The trailer is next to an MRI facility, not sure if that matters.

[Samantha Hill - remove TRASH t]

[hallerb]

might be a main filter in the main building.......

thats my guess

[Mikepier]

No this is a straight foward dedicated DSL modem, no phone lines. There is no filter.

[hallerb]

quoted text -

the modem plugs into a phone line.

connect a phone at the construction trailer, do you get a dial tone?

[Bob]

they've got dsl now without phone line. i think that's what he has. works at the demarc and doesn't work at the trailor. prob got the wrong pair.

[Mikepier]

quoted text -

This is a single pair modem. As I said it works right before it leaves the building. I tried all 6 pairs going to the trailer ( 5 phones work out there now, and I confirmed all pairs are good). I googled this topic and they say it might be something electrical interfering. One site suggested shutting off electrical breakers except the outlet powering the modem and go from there. It could be a reversed polarity outlet. I'm really stumped. The trailer is only 100 feet away from the main building.

[Reed]

What is distance from main bldg to trailer ?? Could you leave modem in main bldg and extend the Ethernet cable to the trailer ??

or wireless WiFi ??

Not the best, but could be workarounds.

[aemeijers]

I think you are on the right trail with interference idea. Bringing it back in on the other pair and having it work fine means the cable is okay. (The cable twist cuts down the interference.) Is there a good ground connection on the power out in the trailer? Can you string a couple extension cords from the building during off hours and try different power? Could be the MRI unit- those throw off EM and RF like mad. Ever seen how funny the video looks when a TV station tries to roll tape in the room when it is running? Just for giggles, I'd try a long extension cord and a long cat5 cable, and see if the modem and computer work in the cab of your truck as far as you can get from the MRI building.

You could always line the trailer with expanded mesh or even chicken wire, and make it into a Faraday cage... :^/

[TWayne]

Uhh, it is CAT5 or better wire, right? Replace one at the 50' point & see if it'll work there. I'm betting on something wrong with the wires. REgular phone cable will never work over 100'.

You said the modem was in the building and you're running 6 pairs 100'? Why? Better to have the modem in the trailer. Assuming you really mean "modem". What is your "modem"? Why do you think 100' isn't too far away? What kind if wire is used to/from the modem in/out? Are you using the shielded type wires? Are you ignoring the ground pins or using them? Etc..

[hallerb]

ing on

you really mean

n't too far

do the lights light up flash etc on the modem in the trailer, like they do in the building?

[Mikepier]

Like I said, I did a loopback test of over 900 feet of regular 100 pair Cat 3 riser cable: From where it comes into the main building in Ma Bells' frame closet, 450 feet away to the communicaton closet right before it leaves the building to go out to the trailer, then looped back 450 feet to Ma Bells frame again. It works. Distance is not the issue.

The outdoor cable is called "Alpath". It is basically a rigid 6 pair outdoor cable in thick jacket filled with silicone. The modem I am trying to get working is in the trailer. It looks basically like a broadband modem with wireless capability. What I said was I tried out the modem box in the main building and it works.

[mm]

Very good question. He should have told us without your asking.

I once knew what each light meant. I've forgotten but other people know.

Mike, you also didn't answer the question Hallerb asked first. Can you connect a phone to that pair and get a dial tone. Can you do this in the main office and not in the trailer? Or do you have DSL without dialtone?.

[Mikepier]

I thought I did answer that, see 4th post down. This is a straightfoward dedicated DSL, no dial tone.

[Mikepier]

Update: Well I tried turning off all breakers in the trailer, I also tried reversing the plug. No help. I asked one of the MRI physicists if anything might intefere with the DSL in the 1400 KHz range. He said no. I still had an old DSL modem that was previously thought to be defective by the contractor. I plugged it in and it worked. Now everything is fine. The only explanation is that these 2 modems are made by different manufacturers and there are probably different tolerance levels between the 2 involving interference. Thanks for everyones help.

[TWayne]

Sounds like you have the situaiton in hand so all should be well now. Just for the heck of it though a single loopback test isn't proof that it's not distance related if it's the wrong type wiring. It only means that one pair by itself works OK. And CAT3 cable explains a lot, actually. IMO if you have more problems later, which is likely what happened that they originally said that modem was defunct, you need to look into all the suggestions that have been made to you. When it quits working again and if you come back here, try to include the missing details as well as anything else relevant you can think of. Many people had good suggestions and questions which you seemed to ignore. You have wiring problems.

Best of luck,

[Jim Redelfs]

Oh, but is DOES come over a "phone line". It just has no dial tone.

That is called "Stand Alone DSL".

It is delivered over the exact, same pair that runs to that station - with NO dial tone on it.

Troubleshooting "dry" DSL is a royal PITA. I often would "layer" C.O. dial tone (talk line) on the pair during repair. Otherwise, waiting for the DSL tester to train-up (sync) at each test point in the circuit was time consuming and frustrating. With dial tone, it's MUCH easier: No dial tone? The pair is open or seriously faulted somewhere.

[Jim Redelfs]

They all are.

If there is any "bridge tap" ahead of the modem, that may be the cause of the "no train" at the far end.

Dedicate a pair all the way from the demarc/SNID to the back of the modem. Make sure there are no "extensions" tapped onto the pair - make it a "dedicated" pair.

Until DSL was introduced, bridge tapped plant was common in the telco field. The "same" pair would extend off of a main cable and run down more than one county road. This "bridge tap" would prevent DSL from working. Dedicating the pair (removing all the taps) would usually condition the pair to work well with DSL - if within range of the DSLAM.

Bridge tap KILLS DSL.

Also, Cat5 or 6 or whatever is NOT required to provide a good signal to a DSL modem. Generally, if you can TALK on it, DSL will work if the modem is within range of the DSLAM. Cat5 won't hurt, it is just overkill in most POTS installations - and that is what DSL is delivered over: POTS (Plain Old Telephone Service) lines.

DSL is delivered all over the world on Cat 2-1/2 (!) cable that has been in service since the '60s. There weren't even data "categories" then.

Cat5 cable is only needed for the network BEYOND the modem if the ethernet is extended more than a few feet from the modem.

[Bob]

then its not a phone line, its a "dsl line".

yea, like I said dsl without the phone line.

no shit, we thought it came from mars.

[Mikepier]

Update: now the old modem, the one that worked for a while, stopped working. Then I remebered that theAlpath cable goes through a machine room with these huge commercial lights ( like the kind you see lighting Home Depot, Lowes that take a while to turn on). I shut off the lights and both modems work now. So the fact that the phone cable running close to these lights had something to do with it.