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Thread: Shugart 850 rebuild

  1. #11
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    If you can deal with the documentation, the 407 boards are a good platform for retro projects. You get a 168MHz CPU with a 192KB RAM and a half-meg of flash--the boards add support for the real-time-clock and add about 2MB of external flash. There's a header for a WiFi module as well as an LCD display interface, along with the usual "everything but the kitchen sink" peripheral assortment--and almost all of the GPIOs are 5V tolerant.

    All for about $10 shipped. Hard to beat--there's even a version of Linux that runs on it.

  2. #12
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    Quote Originally Posted by Chuck(G) View Post

    All for about $10 shipped.
    From whom? https://www.st.com/en/evaluation-too...discovery.html shows a discovery kit; available from distributor Newark for $20. Equivalent?

    -CH-
    Last edited by clh333; February 19th, 2020 at 10:57 AM.

  3. #13
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    There are many sellers of this board. More features than the "discovery" kits.

  4. #14
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    Went there, did that. My word! We're not in Kansas any more.

    Thx.

    -CH-

  5. #15
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    I found that you can get these with or without the headers already attached, so if you wanted to make a bottom-connect project with it, you could.

  6. #16
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    Package just arrived from Newark Electronics via UPS. I had ordered connectors and pins to replace those that had been cut off. Along with these I ordered a 50-position edge-card connector 3M part # 3415-0001. Cost for single unit quantities is $16.65, which seemed pretty steep to me for a crimp-on connector. With shipping my order came to over $30.

    In the description on the Newark web site (https://www.newark.com/3m/3415-0001/...14_US%2Fsearch) a keying pin is mentioned. It was my error, as Newark Customer Service pointed out when I called, to assume the key was included. Not so: the key is an optional part, cost: $00.29.

    I can get by without the key. I can get by without Newark, too. As my former boss used to say, "Screw me once, shame on you; screw me twice, shame on me."

  7. #17
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    Making progress with the rebuild but I have come to a point where I need to stop and ask for assistance: I was good about taking pictures during disassembly but neglected to document fully the head-actuating assembly as it came apart. Now I find the Shugart docs a little light on the subject and I'm wondering if anyone has an exploded view of the assembly to guide me through this task.

    The spindle motor runs all the time, so to preserve the media the head is raised off the media and lowered by an actuator. The actuator's natural (unactivated) position is "down", but solenoid raises the actuator by impinging on the back of the actuator assembly. Presumably when the solenoid is energized it contracts and lets the head-support assembly lower.

    I have all the parts but I'm not sure I have reassembled them in the right order or quantity.

    Suggestions, please.

    Thanks,

    -CH-

  8. #18

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    I've been examining my two Shugart 850 drives in my Tektronix 4907 floppy disk systems.

    At this time - there is a compatibility problem, and NOS Athana hard sector disks that I formatted and read last summer no longer work on either drive.
    I did format a blank disk, wrote some files, moved to the other drive - it read. I wrote a file with that drive and controller and it read on the first drive.
    Then the next day, it wouldn't read on the first drive

    The Tektronix controllers are 6800 based with discrete TTL digital logic. I suspect part of my problem is in shipment to me one of the drive index sensors was loose and broke a glyptol seal. I moved it back to where I thought the seal indicated and it seemed to work last summer for a while. I'm also going to recheck my termination jumpers - I had disconnected one controller and hooked both drives to the other controller after moving termination and drive select jumpers. I need to recheck my work.

    Here is a picture of the drive - no disk, no power, drive door is closed, head solenoid is up:



    Next picture shows the spring at the rear of the solenoid:



    Monty

  9. #19
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    Hard to tell, but how's the pad on the top (dummy) head? Sometimes those dry out and fall off and nothing reads.

  10. #20

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    Isn't the 850 a double sided drive?

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