Floppy drive repair: Sony F1XV MSX2+

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By aclband1t

Supporter (12)

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10-10-2018, 00:40

Now that I've gotten my keyboard woes probably worked out , it's time to tackle the floppy drive.

Here's the story so far:

Opened it up, turned it over, belt is toast of course. Bits of it are still melded to the spinner, which is gross. Cleaned those off.

Obviously I'll have to buy a belt at some point, but much like I did many years ago when I discovered Famicom Disk System, a rubber band is probably enough to make sure I'm not wasting my money on a belt. I placed one in the proper(? probably?) place around the motor and the spinner.

Running the drive upside-down (and I think right-side-up, but I don't have x-ray vision) like this, it most definitely spins, which is great: the motor's working, and the spinner is still functional. Looking at the platter inside the floppy, it's spinning too, so we're on the right track.

I think it's called the 'head'? The thing that reads the disk? We'll call it that for this post. The 'head' doesn't seem to be moving. The motor that spins the spiral thing that moves the head forward/back, if rotated manually forward (toward the metal center of the floppy platter), most definitely returns to the far-back position. However, it seems never to move from that position.

Before I wrecked my keyboard worse, I was able to 'call format' from BASIC, and it certainly TRIED to format disks, but inevitably failed with errors (sometimes different!) that I unfortunately didn't write down. I can post them once I can type again.

I've only got one floppy game, which I've confirmed at least shows up as data I can read on my Windows 98 PC, but placing it into the machine and turning it on doesn't boot that disk. I think I might need MSX DOS to boot software from floppy, though (having trouble finding good info on this front).

Hopefully that's enough data (maybe too much?) for somebody to help me start diagnosing this thing.

So, what's next?

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By aclband1t

Supporter (12)

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11-10-2018, 16:07

In case somebody bumps into my thread in the future, seems like you don't need MSX DOS to boot software from floppy.

This looks like a pretty good guide:
http://fms.komkon.org/MSX/Docs/EasyGuide.txt

By Wild_Penguin

Champion (479)

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11-10-2018, 16:19

It's quite well known that MSX-DOS2 requires a ROM component to boot. But MSXDOS(1) does not, and is perfectly fine for most simple usage (EDIT: and strictly speaking, you do not even need DOS to use floppies but can use them with plain BASIC, too). Of course, this is not common knowledge for someone just starting to use MSX (or MSX disk drives) Smile

From your problem description, I suspect something controlling the head movement motor is broken. I'd say, it's probably not the motor itself (since it moves in one direction), though I'm no electrical motor expdert. I'd check the cables and traces going to the motor. Then check the motor manually (find out at what voltage it moves, and try to apply voltage manually to see if it moves etc) and/or get an oscilloscope, find the controlling chips, dwell into documentation (if availabe) and try to figure out what is wrong...

Is it the original floppy drive of the F1XV, or a replaced one? Is there a service manual (for F1XV)? It might have service instructions for the floppy drive, too. Also, floppy drives are replaceable in MSXes. Some even use (close to) Shugart pinout, some don't (in which case an adapter is possible, but annoying to build...).

By Wolverine_nl

Paladin (939)

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11-10-2018, 16:34

On a side-note: Someone pointed out to me recently, something which is very logic, that you always need a Diskrom in your MSX to at least run MSX-DOS 1 (which does need a ROM to work if it isn't present in the machine), so some MSX machines cannot just work with an external Floppy Drive.

But your MSX2+ should be fine on that account. There are floppy drives that don't use a belt which are suited for MSX, or modded so they can work with MSX, on some machines you need to make a connector convertor.

By T.R.

Rookie (18)

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11-10-2018, 17:22

> some MSX machines cannot just work with an external Floppy Drive

Doesn't every external floppy drive come with an interface cartridge containing disk rom?

By hamlet

Scribe (1736)

hamlet's picture

11-10-2018, 17:30

Every MSX that come with a build in drive has a disk ROM build in, too. Some of them have connectors for a second drive. Ie comes the Philips VG8235 wit a single sided disk drive but supports a double sided external drive as drive b:.
If your MSX don't have a build in drive, it needs a interface with the disk ROM.

By Wolverine_nl

Paladin (939)

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11-10-2018, 20:33

T.R. wrote:

> some MSX machines cannot just work with an external Floppy Drive

Doesn't every external floppy drive come with an interface cartridge containing disk rom?

No, not every external drive has this, I used to have an external drive that didn't connect via cartridge slot, so this drive didn't have the diskrom. I used it on a msx2 with the diskrom inside, so it did not matter, it was connected on the back of the machine. BUt this external drive could not work on a MSX without diskrom.

By T.R.

Rookie (18)

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11-10-2018, 23:28

Yes but you said that some MSX can't work with a disk drive because they lack a disk rom. My understanding was that the interface cartridges that come with most external disk drives contain a disk rom as well as disc controller. Of course you can have an external disk drive with FDD connector and no interface cartridge, but you won't be able to connect these to an MSX that lacks disk rom anyway.

By hamlet

Scribe (1736)

hamlet's picture

11-10-2018, 23:34

T.R. you got it.

By Grauw

Enlighted (7409)

Grauw's picture

11-10-2018, 23:39

Edit: never mind, what I wrote here was already said Smile.

By Wolverine_nl

Paladin (939)

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12-10-2018, 12:19

it doesn't matter, I used to have a 720kb external 3.5" floppy drive, it was meant for the I/O port connection. So not EVERY external drive came with an interface containing disk rom. Maybe I am reading your sentence too literal sorry. And yes, it is logic that the ones that came with an interface had the disk rom/controller. The ones without it, didn't.
ON-TOPIC:
You indeed do not need MSX-DOS to boot from floppy. You can create an autoexec.bas which will "automatically execute" whatever you program into it.
Some programs/games back in the day, booted with a custom bootsector which even skipped the BASIC screen.

Did you already decide if you are going to find a replacement drive original, or maybe a prepared PC drive (without belt)?

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