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IBM Selectric III

Discussion in 'Electronic Repair' started by [email protected], Jan 28, 2008.

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  1. Guest

    I have had a Selectric III for quite a few years and it has always
    worked perfectly. As I was using it today, and while it was working
    just fine, in mid-sentence, it began typing characters that didn't
    correspond to the keys I was hitting. Any idea what's going on? It's
    never done this before.
  2. PeterD

    PeterD Guest

    Other than the motor there is nothing electronic about this

    But, been there, done that. Check the cables that shift the ball, one
    i sprobably broken.
  3. mc

    mc Guest

    You can probably get another used Selectric III very cheaply.
  4. James Sweet

    James Sweet Guest

    Can you? I remember those, I haven't seen one in years. Seems like the sort
    of thing that would be collectible some day if it isn't already.
  5. A bunch on eBay, most not very cheap though.

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  6. When someone says their Selectric is suddenly typing the wrong characters, I
    wonder whether this is a troll.

    The ball can be put on only one way, and locks in place. It isn't clear how
    it could suddenly slip.

    The mechanism that moves the ball is, if I remember correctly, laterally
    "balanced". If it broke, it seems the symptoms would be more serious than
    just the wrong characters.
  7. mc

    mc Guest

    Teeth broken off the bottom of the ball are another way to get wrong
  8. Good morning.
    It can happen. The tilt and rotate tapes get the ball in the general
    vicinity of the correct character, then the alignment pawls, one vertical
    for the part the ball mounts on and another horizontal that engages with
    teeth in the bottom of the ball itself, engage to ensure correct alignment
    by the time the ball fires into the platen. Any problem with any of these
    can cause incorrect or incomplete characters being printed. The tapes drive
    the ball in one direction, spring tension alone pulls it back in the other.

    Lee Richardson
  9. isw

    isw Guest

    A pair of thin metal strips impart "tilt" and "rotate" motions to the
    ball. You can see those strips not very far down inside the typewriter
    (they run from one side to the other, and connect to the ball carrier),
    and if you push on them (gently), the ball should move appropriately.

    Two possibilities:

    1) One of the strips is broken. That should be easy enough to discover.

    2) One or both of the mechanisms that pull on the strips has fallen out
    of adjustment (the nature of a Selectric is that the adjustments tend to
    be "binary"; i.e. either they're right, or they're NOT). If that is the
    case, it should be possible to readjust things to work properly again.

    I haven't adjusted a Selectric for a *long* time, but if you're
    "mechanically inclined", you should be able to find the appropriate
    adjustment, which will be some sort of threaded rod or screw, or
    something similar. AIR, there is a pair of vertical arms with pulleys on
    the tops for those metal strips to pass around, on the left side as
    viewed from the keyboard. They move laterally according to how many
    levels of "tilt" or "rotate" is necessary to position the desired
    character on the ball.

    Looking at the ball, and the incorrect letters being printed, should let
    you discern whether it's "tilt" or "rotate" that's in error.

    If you can find the adjustment, crank it one way until it's wrong, then
    the other, counting turns, and then set it back half way between. I
    don't think that being "wrong" can cause any damage; just incorrect
    letters being printed.


    The Selectric is probably the last and most wonderful "mechanical
    mechanism" ever to be designed (there's nothing "electrical" in one
    except for the motor, which just rotates a shaft; everything else is
    purely mechanical). It really is a magnificent piece of engineering. It
    includes, among other nifty features, a totally mechanical two-key
    rollover, and a simple but clever device that absolutely forbids
    multiple keys being depressed simultaneously.

  10. isw

    isw Guest

    Nope; just incorrect characters, that's all. If one or the other of the
    bands breaks, then only a "vertical" or "horizontal" subset of
    characters can be selected. If one of the band "drivers" becomes
    maladjusted, then characters above, below, to the right, or to the left,
    of the desired one will be selected. A comparison of the source to the
    printed output vis-a-vis the position of the characters on the ball will
    give a lot of clues.

  11. isw

    isw Guest

    True, but I've seen balls so used that the metal plating was mostly worn
    off, but with intact teeth; I don't think there's any way for them to
    get broken while installed.

    (That Selectric had been used in an airline reservation system; there
    was a "crater' on the platen at every possible character location.)

  12. mc

    mc Guest

    I agree. It is probably the last of the world's great purely mechanical
    machines (with no electrical control signaling, only mechanical movements).
    I have a Selectric II in my office which I bought in 1975 and still use
    occasionally. I had the University's typewriter technician overhaul it for
    me just before he retired, so it will probably last me the rest of my life.
  13. Larry

    Larry Guest

    : I have had a Selectric III for quite a few years and it has always
    : worked perfectly. As I was using it today, and while it was working
    : just fine, in mid-sentence, it began typing characters that didn't
    : correspond to the keys I was hitting. Any idea what's going on? It's
    : never done this before.

    These 3 items would cause wrong characters that would not be perfectlt
    formed characters:

    1. Take the ball off and look up the centre of it. Is there a thin groove
    in the circular piece or is that broken out?

    2. While the ball is off, check the back of the tilt ring (thing the ball
    mounts on) and see if the vertical spring on the back of it is not broken.
    This spring pulls the rotate detent up and locks the ball in position
    rotationally when it strikes the paper.

    3. With the ball still off; on the left side of the tilt ring is the tilt
    detent which locks the tilt ring in one of the 4 rows of letters when the
    ball strikes the paper. It is a vertical spring that you can see to the
    left and on the left side of the left post.

    If the characters are wrong but perfectly formed, my guess would be a broken
    spring down inside on one of the selector interposers. You would likely
    need to get help to find this. There are people repairing them still. Try
    Googling selectric repair. Here is one I found
    Where do you live?

    Larry (Retired IBM tech)
    larry17 at
  15. As well as the Rotate Tape and the Tilt Tape which shift the golf ball to
    its various character positions, there are keyboard interposers and
    selection latches, a couple of mechanisms which can result in suddenly the
    wrong character being typed, without the character being in any way out of
    place. It's been a couple decades since I used to fix hundreds of these,

    Henry Mydlarz
  16. Luc

    Luc Guest

    Actually The Selectric III (3 Pitch) is still widely used by Insurance
    and Trucking companies. I repair plenty of the as well as the II and
    even some 721. I do not sell Selectric III for a low price as the
    demand is still there. You can get a Selectric I for a low cost or a
  17. mc

    mc Guest

    What is a 721?
  18. Guest

    Sometimes, when I always stop off at the Goodwill store on my way to the
    food store, I see a IBM Selectric typewriter for sale.Typewriters in
    that store usually sell for $7.00.

  19. I passed up a free one Saturday at a church yard sale. I did take the
    Nitsuko (NEC) digital PBX and five telephones, though. :)

    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
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