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Telephone wiring 101.

Discussion in 'Electronic Repair' started by David Farber, Jul 14, 2010.

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  1. David Farber

    David Farber Guest

    I moved into a new house and have new voip phone service via the local cable
    company. The way it's configured is the cable from outside goes into the
    modem, model number Arris TM502G, then the output of the modem, labeled Tel
    1/2 goes into a telephone line splitter, then the single ended part of that
    splitter, goes into a telephone wall jack which is supposed to feed the rest
    of the house. The third connection of the splitter goes to my Uniden
    portable phone system, model EXAI3428, which I will call system #1. It works

    To avoid confusion with another Uniden system, a model EXAI5688-3, I'll call
    that system #2. I want to hook up system #2 at a different wall jack in
    another room. When I did, there was no dial tone. System #2 was working last
    week in another home so I am fairly certain that it was ok. I have a
    telephone line polarity checker probably better known as, "The Fox," made by
    Triplett Corporation. The l.e.d. lights up when I plug it into the back of
    the modem. When I remove the telephone line from system #1 and plug in the
    Fox into the splitter, it doesn't light up. I disassembled the wall jack and
    sure enough, if I hook up the red test lead to the green wire and vice-versa
    for the green test lead, the l.e.d. lights up. Question 1, does it make
    sense that system #1 can work if the polarity is reversed? I removed the Fox
    and plugged system #2 in the same jack. System #2 didn't work. Then I
    reversed the red and green wires in the wall jack and tried system #2 in the
    wall jack in the other room. Still no dial tone. So I disassembled the wires
    in that wall jack. The wires were so snug that I could only pull it out from
    the wall about 1 inch. I looked behind the jack and saw that the phone wires
    were the old style red, green, yellow, black wiring. When I reversed the
    wires in the wall jack back in the room where system #1 was, I noticed the
    wires were a white/blue pair. I then plugged the Fox into a jack in a third
    room. The Fox lit up. I plugged in system #2 into the third room and got a
    dial tone. Question #2, is there a way to get the red and green wires in the
    wall jack that isn't working tied into the blue/white pair at the outside
    box? And finally, why does the telephone line splitter reverse the polarity?
    I tried another splitter and it did the same thing.

    Thanks for your reply.
  2. David Farber

    David Farber Guest

    Hi Mike,

    As I pointed out, the polarity did matter because system #2 did not work
    until I reversed the wires in the phone jack. Regarding the load on the
    line, does a portable phone system which has its own power supply place the
    same amount of load on the line as a stand-alone telephone?

    Thanks for your reply.
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