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Thread: Docs needed for TRS -80 Model II Disk System

  1. #11
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    Charles,
    some RS equipment labeled "TEC"
    is Tokyo Electric Corp. The FB-504 Floppy schematic is in the "Disk Video Interface Service Manual.pdf"

    Larry

  2. #12
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    TPI did produce a 5.25" Tandon drive clone that went through various iterations--one being with the track zero switch glued in place instead of being adjustable. we had quite a time convincing them this wasn't such a good idea, but they finally relented. there were other running changes--but that's not about the Model II. anything manufactured by TPI is stamped TPI.

    I don't think we're talking about the same CDC 8" drives from you description. regardless, they are delicate and lose alignment almost as soon as you finish with it.
    Last edited by shank; March 17th, 2020 at 07:49 AM.

  3. #13
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    Quote Originally Posted by ldkraemer View Post
    is Tokyo Electric Corp. The FB-504 Floppy schematic is in the "Disk Video Interface Service Manual.pdf"
    Thanks Larry. I am continually amazed at the breadth of your knowledge.

    -CH-

  4. #14
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    Quote Originally Posted by shank View Post
    TPI did produce a 5.25" Tandon drive clone that went through various iterations--one being with the track zero switch glued in place instead of being adjustable. we had quite a time convincing them this wasn't such a good idea, but they finally relented. ...
    Even I know that's not a good idea...

    Quote Originally Posted by shank View Post
    anything manufactured by TPI is stamped TPI.
    I'm learning that Tandy had a wide network of suppliers.

    Quote Originally Posted by shank View Post
    I don't think we're talking about the same CDC 8" drives from you description. regardless, they are delicate and lose alignment almost as soon as you finish with it.
    I may have a line on Shugart replacements. Any weak spots in the power supply? Weighs a ton and probably could light a city block.

    Thanks again for the benefit of your expert knowledge.

    -CH-

  5. #15
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    CH

    re: power supply. there are numerous threads here that deal with the MII ps. be sure to look them over. don't run it unloaded!

  6. #16
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    Quote Originally Posted by shank View Post
    CH

    re: power supply. there are numerous threads here that deal with the MII ps. be sure to look them over. don't run it unloaded!
    Took a look inside. Pictures attached. Drives are Magnetic Peripherals / Control Data. SSDD I think. I misconstrued their orientation; top of drive is right, not left as I had assumed, so release is at the bottom, door is actuated with a spring-loaded rod as shank recalled. Space and power + data connectors for a third drive.

    Turned the spindle by hand on both drives, heard a little clunking but things freed up after a few revolutions. Tried turning the stepper screw by hand but didn't feel right so I rotated it back. Inside the case is a thin layer of fine dirt / grit such as accumulates in an industrial environment. Astec PSU looks reasonably healthy for an old-timer but who knows.

    This has a repair sticker from 1984 on the case and on the frame.

    -CH-

    IMG_3349.JPG IMG_3351.JPG IMG_3355.JPG IMG_3362.JPG IMG_3365.JPG IMG_3366.JPG

  7. #17
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    Quote Originally Posted by clh333 View Post
    This has a repair sticker from 1984 on the case and on the frame.

    -CH-
    looks pretty good in there! definitely clean and get the grit off the worm gear before proceeding too far. some recapping on that supply, probably covered in other threads, and check the voltages. i figure you'd do that anyway. no adjustments on that supply.

    what shop did the work? i probably know who last had their hands in there.

  8. #18
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    Quote Originally Posted by shank View Post
    what shop did the work? i probably know who last had their hands in there.
    See attached. Looks like Tony at shop 7130. Anyone you know?

    -CH-

    IMG_3369.jpg IMG_3371.jpg

  9. #19
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    Quote Originally Posted by clh333 View Post
    See attached. Looks like Tony at shop 7130. Anyone you know?

    -CH-
    I vaguely remember a Tony, but not sure what shop he was with. 01-7130 might have been the Cleveland shop--I think. I don't seem to have a service center list anymore--maybe someone here has come across one. We had techs (both male and female) we talked to all the time; some, not so much. There were around 150 company shops doing computer work (some with quite a few techs, but others as one tech shops), plus some full-line as well as franchise that push that number even higher. All company computer service centers handled in-shop and on-site component level service for the Z80 based systems and printers and on into the Intel years...

  10. #20
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    Completely disassembled the unit. I will be cleaning and testing the drives independent of the RS power supply, pictured below, which will need repair before I apply power. The 0.1 uf high-voltage paper-foil capacitor in the lower right shows cracks, for example, and for good measure I will replace all similar.

    Would you replace ALL caps? Electrolytics don't display any signs of bulge or leakage, but I have no way to test them in circuit.

    -CH-

    PSU.jpg

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