Broadband modem glitch

  kevvyb 11:27 10 Aug 2003

I have been meaning to sort thisout for some time and have only just got around to it.

I have a Dynamode PCI adsl modem which I installed myself.

When the PC is switched off there is always a high pitched tone that can be heard when using the telephone. Turn the PC on (modem connects) and the tone disappears.

Anyone have any idea what might be causing this and how I might be able to eradicate it? Dynamode are not very responsive.

  Terrahawk 11:32 10 Aug 2003

just a thought have you installed adsl filters on the phone line

  kevvyb 13:02 10 Aug 2003


Filters on all sockets where there is a telephone connected.

  sil_ver 13:12 10 Aug 2003

Does the tone disappear if you disconnect PC from the mains supply or if you disconnect the modem? If so, could it have anything to do with the BIOS being set to 'Wake up on LAN' or something similar. Or am I talking rubbish :-))

  kevvyb 18:51 11 Aug 2003

Tone disappears when adsl modem is unplugged.

  graham√ 19:43 11 Aug 2003

Unplug everything except the modem, PC switched off. Plug in one filter and one phone, check for the tone. Try other phones in the same socket with the same filter.

Repeat this until every combination of socket, filter and phone has been tried. You should be able to narrow the fault down to one component.

  kevvyb 20:12 11 Aug 2003

Thanks Graham. Will give that a go but will not be able to do it until the end of the week.

One thing that occurs to me is that my modem(s) are not plugged directly into the socket. I have a filter plugged into the socket into which I have my adsl and my dial up modem connected. The socket I have is a standard telephone socket and so would not take the adsl modem plug directly. Just wondering if this might be the cause? (no telephone connected on this socket).

  graham√ 20:47 11 Aug 2003

Did the ADSL modem not come with a lead/adaptor to connect directly to the phone socket? You will have to include the dial-up modem in the tests as above, so unplug that as well, leaving just the ADSL modem connected (via a filter if you don't have a lead/adaptor).

Also check the cable to the ADSL modem is away from sources of inducted interference. Come to think of it, listen for the tone and then move the cable around. With the PC turned off, the cable may be in an 'unterminated' state, and more prone to induced noise.

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