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Help With Rotary Phone Wiring

Discussion in 'Electronic Repair' started by [email protected], May 12, 2007.

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  1. Guest

    I have searched the groups already to see if any previous posts could
    help me with my problem, but most either point to sites that no longer
    exist or contain snarky remarks. So let me start by stating, up front:

    1. I am aware of what year it is. It is 2007.
    2. I own a cell phone and subscribe to DSL. I also have a satellite
    dish. My cars have EFI, not a carburetor. So I am not behind the
    times regarding technology.
    3. Not that I owe the sarcastic among us an explanation, <i>but</i> I
    am <i>choosing</i> to augment my touchtone phones with a rotary phone
    because <i>I</i> think it's cool. I really don't care what <i>you</i>
    think, so keep your caustic, derisive comments to yourself.

    Okay, with those unpleasantries behind us, let's begin!

    I just picked up a wall-mounted Western Electric rotary phone. When I
    went to plug it in, I discovered that, while there is a jack on the
    bottom for the handset cord, there isn't one for the line into the

    There is a rounded opening beside the the jack through which nothing
    protrudes, and I cannot discern its purpose. Through it I can see a
    portion of the left-hand ringer bell. On the back, there is, one-
    third the way down, centered horizontally, an oval opening whose
    purpose I also cannot discern. Through it I can see the wires that
    leave the dial assembly, and gear teeth related to the dial mechanism
    are also visible further back. All the wires here are connected to
    things except for two yellow wires which were either cut or are spare.

    Now, removing the cover, the phone is laid out thusly: At the top, of
    course, is the chrome, metal hang-up bar. Below it is the dial
    assembly. Below this, on the left, is a black, rectangular wiring
    block marked NET 425B. On its side is stamped "C NET 425B," then a
    column of ovals marked, top to bottom, "GN," "B," and "R." Beside
    that is a group of markings with "F" and "A" in circles; then "RR" and
    "K" in circles; then an oval that says "G" and a circle containing
    "L1;" and finally an oval containing "L2." Then, in the middle, it
    says "8-58." This is clearly a diagram of the wiring block, though I
    have no idea what these letters stand for. Beside the wiring block to
    the right is a tape-wrapped electrical coil that almost certainly
    powers the ringer. The bells are below these, the low-tone beneath
    the wiring block and the high-tone beneath the coil. Stamped on the
    inside of the phone's backing plate are the numbers "554BMP," and
    there's a white sticker that says "8-75." (Is this a manufacture
    date? That'd be cool to know, because it would mean that the phone is
    three months older than I am.)

    So! I need some kind soul to help me figure out what I'm looking at
    here so that I can wire this antique into my home line. There's
    nothing fancy with the home wiring; I have a single line with DSL
    filters installed. If someone could just tell me how to get a line
    out of this phone I'd sure appreciate it.

    Do I just splice red and green wires from a phone line into the
    switchblock? Both the red and green wires from the handset jack are
    screwed into the same place on the wiring block--is that right? Are
    those two yellow wires coming from the dial assembly extra, or were
    they cut for some reason? Was this thing wired to be a prop phone on
    a stage someplace before it came to me?

    Thanks in advance.
  2. Bob

    Bob Guest

    The phone dates back to a time when all phones were professionally
    installed and jacks were not used. Connect the line to the L1 and L2
    terminals on the block. This assumes that the phone is still wired
    conventionally. For more information see

    These phones were always leased prior to the 1984 Bell System
    divestiture. The insides of them were recycled. From your description,
    the phone was originally manufactured in August 1958, and was
    reconditioned in August 1975. This was in the early days of modular
    connectors and the reconditioned phones were being retrofitted with
    modular plugs.
  3. Ross Herbert

    Ross Herbert Guest

    You might be able to find some help here via references and links
  4. Guest

    Thank you, gentlemen. Looking more closely at the phone, I see that
    the screws to the L1 and L2 taps are backed off, so, you're right,
    this is clearly where the wires lived when last the phone was used.
    Also following what Bob said, I see now that there are other
    components labeled from 1958, so the phone is far older than I'd
    thought! I have a beige table model around in a box, too--I'll have
    to see how old that one is. Probably much newer since it has a
    modular jack installed already.

    In any event, no rest for the weary, as the classic looks of this
    almost-fifty-year-old box will keep it in my service for years to
    come. I'm looking forward to hearing the melodic ring of actual bells
    instead of the electronic equivalent of today's phones.


  5. A lot of 500 series type desk phones were converted to modular when
    they were sent to a service center, so the modular jack is not a real
    indicator of age. Special hand operated notching tools were made to
    convert the older cases to the newer configuration, and tooling was
    available to covert older handsets to modular. There was a large local
    company that rebuilt phones, till they had a fire that destroyed all
    their inventory a few years ago. I knew the owner, and several of the
    field techs that serviced business phone systems so I was in their shop
    quite a few times.

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
  6. Guest

    Update: Installed and working great. Thanks again.
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