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Weird telephone problem

Discussion in 'Electronic Repair' started by David Nebenzahl, Jul 16, 2010.

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  1. (And by telephone I mean the kind God intended us to use, a regular old
    land line, not those Dick Tracy cell-phone thingies.)

    Client has a bunch of phones in their house. Starting a few days ago,
    several of them don't work; pick them up, no dial tone. (Confirmed with
    a good set which I used to test all the jacks.)

    But get this: while I was there, at least one of the phones that doesn't
    work (a wireless phone) rang on an incoming call. WTF?!?!? It rang, but
    when picked up--nothing, dead. No dial tone trying to make a call.

    Anyone familiar with the inner mysteries of the telephone system care to
    try to 'splain this? How could a phone not work, but still ring on an
    incoming call?
  2. Forgot to mention, in case it's relevant, that they also have DSL, and
    some of the phones have in-line DSL filters. Problem remains with or
    without the filters.
  3. Bill Janssen

    Bill Janssen Guest

    Good advice above

    I want to add. you should see about 52 Volts on an idle line and 25
    milliamp or greater current when off hook
    I think to telephone switch will work on 20 milliamp, but that is
    pushing it.The voltage isn't critical but the current is

    Bill K7NOM
  4. How the hell will this help me? Didn't you read my post? I said that
    *some* of the phones (meaning the wiring inside the house) work and some
    of them don't, so obviously the problem is inside the house.
    Nope. It doesn't.
  5. Bite the bullet. Buy a box of Cat-3 (or 5) wire and start over.
    Every house I've ever worked on has a total cluster-f**k for the
    telephone wiring.

    Pick a location, (a closet or such) and call that "home".
    Run a new cable from the telephone company POE, to there.
    From there, run a new cable to each and every jack in the

    One Type-66 split block and a package of jumper clips will
    make a nice "distribution" point in the closet.

    Problem solved.

    And if you decide to get campy and put in a cheap PBX, all
    your work is already done for the most part.

  6. Well, good suggestions all.

    But thanks but no thanks; I'll answer several replies here by saying
    that even though I posted this query, I have no intention of actually
    trying to fix it. Here's why.

    Mainly 'cuz I'm not a telephone repair person. As I get older I try more
    and more to recognize and respect my limitations. I'm not a master of
    all trades. I *might* be able to fix this problem; after all, telephone
    wiring is not exactly rocket science. But still, it has its on
    specialized problems, and I have no test equipment to perform this kind
    of diagnosis, apart from a VOM.

    Plus it's a fairly large house, with lots of wiring inside walls and in
    barely-accessible crawlspaces. Not my idea of fun at all, brushing aside
    piles of old rat shit to trace a wire.

    Plus, the existing wiring is a total fucking mess. Unbelievable how
    those phone co. monkeys wire stuff. There's a literal rat's nest of
    wiring under the house, not in any box, splices every which way, no
    consistency in the use of color pairs, no labels, just a fucking
    nightmare. So I'll leave it to someone else to sort out, thank you very

    Ackshooly, the homeowners are lucky, because the last time they called
    the telco (AT&T), they got a guy who scurried about under the house,
    found the problem (this was a DSL issue), fixed it, and DIDN'T CHARGE
    THEM ANYTHING FOR IT! They think they can get this person to perform
    another miracle for them.
  7. PeterD

    PeterD Guest

    That would truely be a miracle, and if it happens they should also
    consdier buying a handful of lottery tickets. Heck, just one lottery
    ticket, it will win.
  8. Guest


    Here's how life works. If a man (I'm referring to a real man, not
    some elitest bullshit "I don't want to get my hands dirty" type who
    happens to possess a Y chromosome) sees a problem, he tries to fix it.
    If he can't he asks for help.

    This doesn't reflect unfavorably on his masculinity. When the first
    proto cave-man decided it would be nice to live in a cave rather than
    get wet every time it rained, he asked his proto cave-man buddies for
    advice on getting the wild animals out of the cave of choice. And
    being real men, they probably offered to help. And sat around in the
    cave afterward eating the former four legged occupant.

    If you are going to ask for advice that you don't intend to use, the
    honorable thing to do is to tell us up front that this is purely for
    informational purposes. At a mimimum, afterwards say "Thanks, the
    problem has been solved." That at least give your helpers the
    satisfaction of having spent their time in a useful matter.

    This "I'm not going to do anything about it" is BULLSHIT!!!

  9. I'm sorry you were offended.

    No, I take that back: I'm actually *happy* that you were offended.
  10. You didn't mention this: What happens if you move a non-working phone to
    where a working phone is? Does it now work? If so, then it's a wiring
    issue. Otherwise, it's the phone itself.

    Also, if you have the newer interface where the phone company connects
    to the house that has RJ jacks in it, take all of the phones to it and
    test them with that jack.
  11. Well, I didn't test that, but I did the reverse test which shows that
    the problem is the wiring, not the phone: I took a working phone (a
    regular, non-cordless phone) and plugged it in to a non-working phone
    jack. It was dead, so the problem appears to me to be the wiring.

    The phone that rang on an incoming call, by the way, was a cordless
    (i.e., powered) phone, which tends to confirm the diagnosis someone else
    here gave of a "DC open", a corroded connection that would pass enough
    of the higher ring voltage to make the phone ring, but not enough to go
    "off hook".
  12. David Lesher

    David Lesher Guest

    Agree re: corroded wiring connection as likely cause.

    Go to each jack and put a *milliammeter* across Tip-Ring.
    Start at the demark.

    You should see 20+ mA. If you don't, it's the wiring or jack.

    As a next step, put the meter in series with a phone, and see if the off-hook
    current is still >20mA.

    The first indicts the upstream wiring; the 2nd is likely the phone.
  13. shrtrnd


    Jan 15, 2010
    I'm late to this party, but have two cents worth. Last time this happened to me, telephone company had automatic test that was trying to determine if the problem was in their gear, or my house (so I got ringing on one phone, even though the line was otherwise 'dead'). Apparently the phone company test includes overvoltaging the phone line while looking for the problem. Anyway, I disconnected ALL the phones, and plugged them back in one at a time. Turned-out I had an electrical 'SHORT' across the wires near one of the phone outlets, which effectively disabled all the phones. When I removed the electrical short, problem solved. May not apply here, but wanted to say, dead phone doesn't always mean an electrical 'OPEN', it can also be an electrical 'SHORT' in the line.
  14. Bill Janssen

    Bill Janssen Guest

    The milliampmeter should be in series with a 400 Ohm resister. The
    resister represents the resistance
    in the phone.

    Bill K7NOM
  15. David Lesher

    David Lesher Guest

    Not needed at all, and misses the point. The phone is not a
    fixed resistance; it's a small voltage drop that varies with
    loop length.

    The outside plant loop and the line relay at the CO limit the
    current. Let's say you are 5000 ft from the CO; that's 250 ohms
    right there. The line relay is say 500 ohms. Worst case, 60 odd
    mA. In reality the line card will limit it to far less.

    Nothing you can do to your end of the loop will damage anything.

    Your goal is to see the max available current. If it's not
    sufficient at a jack, but is at the demark; there must be a bad
    splice in the IW. And measuring the voltage with a open circuit is
    sorta pointless.
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