Can a switch mode PS cause this sort of ADSL noise?

Chris Wilson · 18 Jul 2013 at 15:37

Having received a new router from Zen and found it cured some of my ills opf dropped or high noise connections (a Technicolour TG582n) I decided to wire it up properly. My home LAN is wired, no wireless at all. I had been testing with the router connected to the test socket in the BT master socket in the loft via a LONG Ebay purchased cable. I fitted a new latest filtered faceplate with the extra two AB connectors so the wiring to the router socket was hidden. I reconnected the BT installed twisted pair cabling to the AB connectors, and another pair to 2 and 5 for the phone socket in my office. All seemed well for a few hours, but in the night routerstats showed serious noise and the connection speed dropped substantially. Connecting via the extension cable brought a quiet connection again. I decided to follow the BT laid cable and in so doing was forced to recall I had 2 switched mode power supplies on the opposite side of a studded wall, just near the sockets in my office. The cable ran *RIGHT* by them and alongside a mains cable feeding their 13 amp dual mains socket. One is for a Thunderbolt 10 MHz frequency standard, the other for a frequency divider board. I use them in my amateur radio hobby. The Thunderbolt box itself is slso very near the socket and wiring. These supplies runs 24 hours a day, seven days a week and have done for at least 2 years. I decided to turn them off and reconnect the BT wire. All has been quiet since and I am slightly optimistic one may have been the problem. I am perhaps lucky and not had issues with switch mode supplies causing noise that I have been aware of, so could some of the more knowledgeable folk tell me if this screen shot of the noise margin when playing up could be a SMPS gone awry? Thanks!

Chris Wilson · 18 Jul 2013 at 21:36

You are right about hard to find! The damned noise is back and both supplies are unplugged. Seriously considering satellite, the neighbours have issues too. The joy of being out in the sticks I guess

Thanks for the replyTealc

Chris Wilson · 19 Jul 2013 at 22:36

How can I post the line stats? I believe the issue is on the spur to my office. Currently running the 2 phones in the house and an independent Ebay extension cable direct to the router from the faceplate "router" port on a new master socket. All seems well. I have resistance tested the BT installed line to my office, with one end shorted, and chopped off the ends in case fiddling has flexed and broken a solid core wie juist inside the cable pairings. Seems it's a strange internal fault on the cable to my office from the master socket. I was going to go satellite but I now see Tooway are also having connectivity issues, so feel more obliged to persevere with ADSL. Being in the sticks I accept ADSL won't be perfect, but the situation for the last few months has been ridiculous. I am loathe to have BT in and for them to find an issue withb the internal wiring, so I am very open to further suggestions. Thanks Tealc

Chris Wilson · 20 Jul 2013 at 09:12

Here's a link to a screenshot of the current line stats. Zen organised a bRAS reset late yesterday afternoon and things are fine now I have removed the spur to my office and am using a cheap extension cable from the fascia router port on the ADSL 1.0 master box direct to my router. I am hoping it stays this way and I can rewire from scratch the office socket, probably moving it to an opposite partition wall in case it was picking up RF from something. Thanks for the CAT5 tip, I have a reel of CAT6 and will wire with that if it seems to be the issue.

http://www.gatesgarth.com/routerstats.jpg