FM Towns Marty floppy drive problems - motor keeps spinning, drive access light doesn't flash.

Discussion in 'Repair, Restoration, Conservation and Preservation' started by DeChief, Mar 10, 2018.

  1. DeChief

    DeChief Rustled.

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    I've got 5 FM Towns Marty consoles at the moment, and all of them had floppy drives with brittle belts so I ordered some replacement belts from console5. They arrived yesterday so I installed a belt onto one of the Marty floppy drives, but once I turned the console on and put a disk into it, the drive motor immediately started spinning and didn't stop until I turned the console off.

    The access light doesn't come on at all (not solid, not flashing; nothing), and when I try to format the disk using the Marty's menu, it keeps telling me there's no disk inserted. I've tried both HD (1.44mb) and 2DD (720kb) disks to no avail.

    I've tried swapping power supplies, motherboards, and even CD assemblies (can't see how they could affect the FDD, but you never know...), and still nothing. I noticed that there's a single capacitor right at the back of the FDD's board, but what are the chances that it's dead on all 5 of them? Should I get a replacement capacitor anyway?

    Any ideas? One of these is a pretty uncommon Virtual Towns TC Marty, so I'd like to at least get one drive working.
     
  2. Tokimemofan

    Tokimemofan Intrepid Member

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    I would carefully check your cables, make sure they are all in correctly and make sure the disk detect switch’s are working. FYI this is why I hate 3.5 floppies. The drives are unbelievably primitive but don’t have the manual clamp of the 5.25 design. The only caveat is that I only have experience with pc and amiga floppy drives, but the principal is the same, apply power to the bare drive to rule out a system issue then check the switches for obstruction or failure, double check your reassembly if the unit, all else fails buy a working floppy drive and compare. I would bet on technician error or mechanical problems long before looking at electronic failure.
     
  3. Uroko Sakanabito

    Uroko Sakanabito Spirited Member

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    ALWAYS recap the power supply and all caps on the mainboard!
    Power supply is 100% needed for correct CD and diskette function.
    The caps on the mainboard can damage everything or ruin the sound.

    I bet it will work with a recapped one, no worries about fmt floppys they still work very good today.
     
  4. DeChief

    DeChief Rustled.

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    My logic is that for the drive to start spinning, the disk detection mechanism must be working. As soon as you eject the floppy, it stops spinning. I've checked all of the cable multiple times and everything should be fine. I can't really buy a working floppy drive because FM Towns drives don't have a power connector, and instead have the power go through the same cable as all the data - and FM Towns drives are hard to come by on their own, and in guaranteed working order. That cable also just so happens to be one of those thin 1-sided card type ones and not an IDE-style cable. I should also note that the drive only starts spinning once the Marty has passed its initial loading screen, and once you put a disk in it, so unless the Marty can directly control when power is going to the drive, I don't think power is necessarily an issue.
    If every other part of the Marty is working flawlessly, would recapping everything really solve the problem?
     
  5. Tokimemofan

    Tokimemofan Intrepid Member

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    Same reason some turbo duos won’t read discs before recap. Another possible issue is misalignment of the heads.
     
  6. Uroko Sakanabito

    Uroko Sakanabito Spirited Member

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    You can say that your Marty works with full power when it boots something like Pu-Li-Ru-La from CDR, does it? Take a game with heavy loading times. If it does not boot CDRs or just a few you have voltage problems.
     
  7. Bad_Ad84

    Bad_Ad84 The Tick

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    IBM ps/2 computers have no power on the floppies either. But you can just adjust the wiring on the cable and use a normal floppy drive.

    I assume the marty is similar.

    @DeChief you are thinking about powering being on or off. The issues arise with voltage fluctuations, not rising fast enough, noise not being filtered etc. Its not just a "got power" vs "not got power" issue.
     
  8. DeChief

    DeChief Rustled.

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    Is there something that makes the drive spin forever if the head doesn't detect something immediately? If so, that could be the problem, and holy shit realigning floppy drive heads is the worrrsttttt. Do you have a guide you can link me please?
    I've tried a dozen or so games so far, but I'll try that one just to be sure. All of the Marty's boot CD-Rs just fine, but some of them start games without music sometimes and the disc stops spinning - I chalked this up to the fact I'm using modern CD-Rs in a burner only capable of 8x when Marty games were probably burned at 1x back then. Could be the PSU though, like you said.
    Yes, the Marty is similar, I even found a webpage talking about converting a regular floppy drive to work in MSX/FM Towns machines. But naturally the page is poorly translated Japanese and is quite confusing. I'll see if I can give it a shot, but I'll have to buy a NOS drive anyway because funnily enough the only working 3.5" drive I have right now is in an IBM PS/2! :p And I'd rather not mess it up somehow.

    But before all that, I guess I'll try recapping the PSU and motherboard in one of the Martys to see if it makes a difference. Assuming console5's cap list is accurate, I'll go with that. Thanks for all of the advice guys!
     
  9. Tokimemofan

    Tokimemofan Intrepid Member

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    Capacitor problems are like cancer. I once had a turbo duo spin the disc backwards due to a cap i missed. Many floppy drives will spin a nonexistent disc forever if the eject tray is lowered. Remember these things expect to find track 0 on a floppy, what happens when it can’t find it is dependent on the drive’s plan B. Ask a commodore user about that...
     
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  10. Uroko Sakanabito

    Uroko Sakanabito Spirited Member

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    I have fully repaired around 4 Martys so far and aside from different issues the solution was always just caps :) I may have a spare FMT UX drive maybe you can convert this one if you build the cable.
     
  11. Bad_Ad84

    Bad_Ad84 The Tick

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    no no no no

    this is not how it works.
     
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  12. DeChief

    DeChief Rustled.

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    It's not? How does it work?

    I bought a full set of caps for the CD module, mobo, and floppy drive btw, hopefully they'll arrive this week. If it goes well then I'll recap the other Martys too and see if I can even fix the Marty 2 that won't power on.
     
  13. Bad_Ad84

    Bad_Ad84 The Tick

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    Burning speed doesnt directly relate to burn quality.

    You will find most burners burn better at the rated speed of the media, than intentionally burning it slowly.

    Burn quality is mostly influenced by the drive and how well it writes specific media. You can find drives that will write one type of disc really well, but poor on others.

    Also, writers use the media ID of the blank media as a reference for how it should write the disc, based on writing strategies within the firmware.

    Side effect of this is, if the media came out after your drive - it defaults to a basic "one size fits all" strategy, which again is probably poor. This is why people recommending you buy an old writer are incorrect.

    Theres much more to it too, but I have posted it all several times. But basically, writing good quality discs is far more complex than the usual "burn at 2x!!" that gets repeated constantly. This is likely a throw back to when you would get buffer underruns etc with faster burning. Something that has long been solved.
     
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