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Thread: TI-59 programable calculator

  1. #1
    Join Date
    Nov 2008
    Location
    Portsmouth RI
    Posts
    347

    Cool TI-59 programable calculator

    This was the thing that got me interested in computers back in the early 1970's.

    I spotted one on Ebay and thought wow I had so much time learning programing with that calculator. It was so efficient that ~1000 steps/memory was more than you ever needed.

    I felt the urge so I went shopping. Every unit I found were being sold untested a few showed power on but that far from tested. I just picked a cheap one that look good. Having own one 40 years ago I knew it would be best to use the PC-100c printer that was made to attach and power the unit. So I found a cheap one of those also.

    The unit I got at 1st seemed to work OK until I tried the magnetic strip to save a program. The strip went in and did not come out. I took the unit apart and discovered the drive wheel that pull the strip through the computer was now tar.

    After spending a few hour on the net looking for something that could work to replace that rubber wheel I came away with zip. I did know the hub size ID and estimated OD so off to my local ACE hardware store. I spent 30-40 minutes looking at all their part boxes for something that could be use to hack a new part. I settled on something they call an expanding nut. It looked like I could slice a small rubber wheel that would work from it.

    1st try, gear sounds and jerky transport of strip, no read or write. Took gear box apart cleaned and lubed.

    2nd try still jerky, no read or write. Inspected wheel and look like it was not true round. I put the rubber wheel on a 8-32 screw that I'd cut the head off and put in a electric drill. Placing the drill in a vise I turn it on low speed and using a dermal w/cutting wheel attachment attempted to true the wheel by filing off a bit of rubber.

    3rd try, smooth transport & write 100% read 75%, I got the service manual and there is a adjustment to help improve reads so I'll be playing with that.

    .77 cent fix full day of labor. I love it.

    Hope you don't mind a calculator listed here but it really a pre-computer of 1970's vintage.

    framer

  2. #2
    Join Date
    Nov 2008
    Location
    Portsmouth RI
    Posts
    347

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    There was another try before the 2nd and third one. It had started to work then failed after a doz times working. The rubber wheel had slipped part way off the hub. I secured it with super glue and some micro glass beads.

    It has worked 50+ times today 100% read & write.

    framer

  3. #3

    Default

    Definitely a story that I enjoyed reading. Much better to make the journey that led to a working calculator, than to have picked up a working example (I love the idea of getting a bargain as well). I once sourced a replacement tape drive roller from our local ACE - they are SO much better than the box stores for finding these kind of unique solutions, they have everything!

  4. #4
    Join Date
    Nov 2008
    Location
    Portsmouth RI
    Posts
    347

    Default

    Let me expand on how it was fixed.


    The white rubber thing was a grommet that failed to work. That is where this new part will go. The hub that it goes on is 4mm and about the same in width. I sliced a piece of rubber the same size as the hub from an expansion nut, 6-32 x 1/2.







    This is the item that the part was made from. I did have to true it round as stated in the 1st post and secure it using superglue and micro glass beads on the front of the hub.

    This continues to work as I been testing each morning, it's over 100 reads with zero errors.

    Hope the pictures help if you need to fix yours.

    framer

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