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Thread: Repair/Adjustement Teletype 33 tape reader

  1. #1

    Default Repair/Adjustement Teletype 33 tape reader

    Dear all!

    My tape reader has issues... it has difficulties to read the first bit in a row.
    I have cleaned everything, including painfull disassembly/reassembly of the contact block, but the issues remain.

    https://youtu.be/7BjzjfAQ5-w

    Any tape reader adjustment experts here who might have a hint for me how to fix this?

    Best regards
    Stephan

  2. #2

    Default

    Nobody? Or anybody has an idea where I might ask?

  3. #3

    Default

    As I recall, the reader uses "wires and bars" to make electrical contacts based on the physical pins that can protrude through holes in that tape. As I recall, there are 8 "wires", one attached to each bit position via the hole-sensor pins. If the pins are mechanically free to operate (and retract), then I'd check the electrical connection. It might be that the "wire" for the bit position you have trouble with is not making (or breaking) contact with the bar. That could be dirt/tarnish/corrosion, or it could be that the wire is slightly bent out of place and never makes contact. Bending those wires can be a nightmare, though, especially without the right tools. It needs to be exactly right in order to make contact when the pin is up, and break contact when the pin is down (or vice versa - don't recall the exact sense of those contacts). I'm just punting from memory, though.
    - Doug

  4. #4
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    Sanity check here. Have you verified continuity across the sense contacts when it's in the middle of a read?
    = Excellent space heater

  5. #5

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    Also, check that the wires make it all the way to the distributor that serializes the data.
    Dwight

  6. #6
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    Default

    Likewise on the 33, the keyboard and the reader share the distributor. If the keyboard works but the reader does not you are very likely missing something prior to encoding by the distributor.
    = Excellent space heater

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