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Thread: Unique S-100 computer (Z-80/Vector Graphic/Micropolis)

  1. #151

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    Yes they only start spinning once they're selected, and stop spinning after about 5 seconds. I only hear the sound of the hub spinning, no head loading sounds at all.

  2. #152

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    So I decided to go through and give everything another good cleaning. Let the ribbon cable soak with some DeOxIt on the leads and cleaned up the connectors on the drive PCB. Making some progress! Now the solenoid engages and the head snaps down. The worm gear engages and moves the head all the way to the outer edge of the disk. I can see once it reaches the edge, the 0-track switch does get engaged. However, the application is still saying "Seek to track 0 failed". Same thing happens for both drives. But now at least I can see the head only engages on the correct drive when I enter 0 or 1.
    Last edited by nullvalue; May 13th, 2020 at 07:18 AM.

  3. #153

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    Great progress! Use a scope and see if the track 0 signal on the interface cable (pin 26) is getting asserted (asserted = low). Look at the signal on the drive PCB and then on the floppy controller PCB and see where it is failing. Trace backward as required to its origination on the drive PCB, and/or forward to it's final destination in the latch on the floppy controller end.

    Mike

  4. #154

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    Awesome, will do - is the track 0 signal simply asserted by that switch, or is there more involved than that?
    Last edited by nullvalue; May 13th, 2020 at 08:32 AM.

  5. #155

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    The track 0 switches goes through a couple of connectors and gates before driving the cable connector. You can find schematics towards the end of this manual: https://deramp.com/downloads/floppy_...6%20Manual.pdf.

    These schematics are for the single drive board, not the two-drive board like you have, but it'll give you the idea.

    The disk controller schematic in the computer is here: https://deramp.com/downloads/vector_...Controller.pdf

    Mike

  6. #156

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    Well I didn't really do anything but I'm back to the head not moving at all again. For drive #1, I can fool it into thinking it found track 0 by just starting it in that position. I just wanted to test the app. Sending XMODEM data over port C seems to work because after a while, it spins up the disk and I can assume it's trying to write. Of course it fails (write failure on track 0). I can't get fool it for drive #0 though for some reason. But for now I'm back to trying to figure out why the heads won't move. The correct solenoid engages and the head snaps down.. but the steppers aren't working. I took it apart and meticulously cleaned every pin/connector and the inside of the ribbon cable. Everywhere a connection is made. Still can't get it to work again.

  7. #157

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    I swear I may have no hair left at the end of this. For some reason it just decided to work.. head's moving.. Do you think I should replace the caps on the board? So I tried writing a disk.. tried a couple times now.. blank disk in, both drive 0 and drive 1. Once the transfer hits 52,864 bytes it starts writing. Every time I get a "Write failure on track 0, sector 7." (although the sector that fails seems to change) - any thoughts?

    Edit: side question - while I do want to get the actual hardware floppy drive working, do you think it would be possible to get a Gotek working with this setup?
    Last edited by nullvalue; May 18th, 2020 at 05:45 PM.

  8. #158

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    If you’re to the point that PC2FLOP is writing and verifying, then it is failing on the read. It’s time to calibrate the pots on the FDC. It’s pretty easy to do. Look at the “Tests and Adjustments” section of the controller manual https://deramp.com/downloads/vector_...Controller.pdf

    Mike

  9. #159

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    Thanks I'll check it out! But how do we know it's writing successfully and failing to read - and not just failing to write? Or would the same adjustments fix this?

    Also how would I invoke the read/write operations it's talking about in tests 2.1.3 and 2.1.4?
    Last edited by nullvalue; May 19th, 2020 at 06:03 PM.

  10. #160

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    From what I recall, you can get the measurements while it’s stuck in the loop trying to boot.

    Mike

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