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Weak telephone line

Discussion in 'Electronic Basics' started by Dan Beck, May 18, 2005.

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  1. Dan Beck

    Dan Beck Guest

    Hello all,

    I just purchased a printer/copier/fax combination device. I successfully
    installed it, and its software on my PC. Going through the test procedures
    I was told my fax line has a weak signal. Are there any hints, tricks, or
    modifications I can do, before I have to call the telephone company?

    Thank you in advance for reading.

    Dan
     
  2. Art

    Art Guest

    Hook a working phone to it and see if there is a lot of noise being
    produced, then try to determine if it is from the phone company or being
    produced within your residence. May just be a poor interconnect in the
    in-residence wiring.
     
  3. w_tom

    w_tom Guest

    You are responsible for interior wires. They are
    responsible for exterior wires. The interface is called a
    Network Interface Device (NID). Designed so that you do
    diagnostics up front. Run a phone wire directly from your fax
    to that NID (a long telephone extension cord). Open the box
    (with a screw driver). Unplug the interior wire from your
    building. Plug in the telephone extension cord. Now test the
    line.

    If the signal is proper strength, then the problem is
    interior wiring. If the signal is low strength, then call the
    telco. Everything they do to fix the exterior wire is free.

    If you don't do this test up front, then either you will not
    get telco service fixed the first time, OR they will charge
    you to fix your interior wiring at what could be expensive.
    This is how you break a problem down into parts, and then
    debug each part. All before trying to fix anything.
     
  4. D Akers

    D Akers Guest

    Dan Beck wrote;
    "I just purchased a printer/copier/fax combination device. I
    successfully installed it, and its software on my PC. Going through the
    test procedures I was told my fax line has a weak signal. Are there any
    hints, tricks, or modifications I can do, before I have to call the
    telephone company? "
    _____________________________________
    Re;
    What I would do is perform what is known as a "loop test". With all
    other phones and equipment "off of that line or on-hook", connect a
    200-ohm, 1/4 watt resistor (you can use 2 100-ohm resistors in series)
    across the red (TIP) and green (RING) of that line at that telephone
    outlet. Within a few seconds (before the off-hook response), connect a
    DC voltmeter across this 200 ohm resistor. You should measure at least
    4VDC across the resistor; indicating that at least 20 mA loop current is
    available.

    As a "line check", simply measure the DC voltage between the red and
    green wires at the telephone outlet in question; you should get at least
    40 VDC.

    Be careful. The phone lines can deliver a mild shock, especially if a
    "ring" signal comes in from an incoming call. It is best to short them
    (green and red) together while you are handling the leads.

    I hope that helps...

    -Dan Akers
     
  5. The advice given by w_tom was okay, but his mistake was to not consider
    the fax machine as a possible suspect. If you measure the current of
    the phone line with a milliammeter and it's 25 to 50 mA, then that's a
    normal amount of current. If your phone is a long way from the central
    office and the current is well below 20mA, then you might consider it
    "weak". But there are fax machines out there that are just too critical
    and complain about a situation that's not really a problem. In that
    case, you might be better off replacing the fax machine.
     
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