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After several years of near flawless connectivity, the modem began locking up. When this happened everything looked fine. The lights on the modem stayed on, and there were no error messages in the system logs of the connected computer, but nothing outside would respond to a ping, or any attempt to connect to a port. Turning the power off (to the modem) and turning it back on would make it work again. This happened several times per day. Between lock-ups everything seemed to work fine.
Then at times the modem would begin restarting itself. When this happened, the lights would blink as though the power had just been turned on. Just when it looked as though it was done with the initialization sequence and ready to go, it would start all over again. Sometimes a successful ping would go through, if it was done at just the right time, but there was never time for two.
For about a week I worried about it; staying up late, waking up early, keeping logs of when it screwed up in hopes of groking the pattern.
Late one night I shined a bright light into some dark corners of the basement, and traced some wires. I found that the main telephone line into the house was connected to one pair of wires in a two pair cable. This cable went to the socket into which the burglar alarm used to be plugged. But there was no longer anything plugged into it! In other words, the main telephone connection to the whole house went into a cable which connected to a dead end socket with nothing plugged into it!
I pried the socket open and looked at it closely. When there is a plug in the socket, it has little wires that touch the wires in the plug. When there is no plug in the socket, the wires spring up and touch some other wires that connect one wire pair in the incoming cable to the other pair. The second pair of wires in the cable was connected to the NID, which is the main connection between the incoming telephone wire and all the wiring inside the house.
That might be a good enough connection for voice, but it is really sketchy for the high frequencies that DSL uses. The main wires into the house would have four open circuits, except that the ends of the wires touch, held together by nothing but their own spring.
I cut the cable to the alarm system, and connected the pair of wires that used to be connected to the second pair in that cable directly to the phone lines coming into the house. Ever since then it has been working well. I met a guy in the local bagel and coffee shop who told me that the socket is called a RJ31X Jack. Click that link for a page that has pictures of the jack, and a more complete description of the way it is wired.
To summarize: if you are installing DSL, do not just unplug the burglar alarm, cut it entirely out of the circuit. Study the RJ31X Jack until you understand how to do that.
More briefly: RJ31X must die!
Alternatively, you could keep the alarm system working by installing the proper DSL splitter before the alarm. I did not do it that way, but The Phone Man has a plan. Good Luck!
Cutting out the RJ31X definitely helped, but a few weeks later the modem began locking up again. I bought a DSL splitter from The Phone Man , It arrived within a week, but it took me a while to get around to buying the cables I needed and installing it. I bought a Wilcom PS-15-I3S and 100 feet of Cat5 cable. I installed the splitter next to the NID, which is an old one located inside the basement. I used the jack to plug in the telephone wiring and ran the Cat5 cable directly from the screw terminals on the splitter to the DSL modem.
With one exception I have never seen the DSL connection lost since installing the splitter. The one exception happened during a storm. I was sitting at the computer and using the DSL when I noticed it was down. I did nothing, but the modem re-initialized itself and began working again withing a minute. I had never before seen it recover without manual intervention. Maybe it goes down and recovers fairly frequently, I don't know. As long as it requires no manual intervention I can live with a minute of down time every now and then.
(checked 2007-07-10) |
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