Floppy drive repair: Sony F1XV MSX2+

Page 2/3
1 | | 3

By aclband1t

Rookie (22)

aclband1t's picture

15-10-2018, 13:09

This thread has been informative so far -- thanks, folks! Sorry for being clueless about starting up floppy disks -- only now becoming familiar with MSX.

To answer some of the points/questions:

Wild_Penguin wrote:

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..."

Got it. I can try (some of) these things and see what I can come up with. At the very least, I can check traces and motor.

Wild_Penguin wrote:

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.

I believe it's the original floppy drive. I'll look around for a service manual (Japanese should be fine).

Wolverine_nl wrote:

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

My goal is to repair this one if possible. If it proves too tough, I am willing to replace it, though.

By aclband1t

Rookie (22)

aclband1t's picture

20-10-2018, 17:01

So now that the keyboard interface has arrived/is working, I can get back to this.

I'm using a two-sided high-density floppy, but with tape covering the hole (which, from what I understand, makes it work correctly as a two-sided double-density floppy).

When it's just been turned on, formatting 'single-sided' initially gives "disk error," and then (only once!) it successfully formatted as 'single-sided'.

After the MSX has been on for a while, though: consistently, when trying to format it as 'single-sided', the motor does move like it's supposed to, and gets all the way to the center (stopping along the way to format the sector). At the end, though, I get the error "Not Ready." When trying to format it as 'double-sided', it goes toward the center about halfway, then says "Not Ready" (very quickly).

Additionally: when the motor is active, the voltage seems to be a solid 4.99V.

By aclband1t

Rookie (22)

aclband1t's picture

20-10-2018, 21:53

Actually, I take back that last statement: seems like the motor is getting a solid 4.99V, but under load (i.e., when spinning), it's dropping to around 3V. Not sure if that's enough to cause trouble or not.

By aclband1t

Rookie (22)

aclband1t's picture

20-10-2018, 22:24

According to this article, I can just toss in a new disk drive without rewiring like many of the other MSX units. I've got a SFD-321B, so I could try that?

By aclband1t

Rookie (22)

aclband1t's picture

20-10-2018, 22:35

Tried powering the drive from a separate power supply, and got the same results ("Not Ready"), so it's likely not a power issue.

By aclband1t

Rookie (22)

aclband1t's picture

20-10-2018, 23:14

Checked the cables from the back of the drive to the mainboard -- all have continuity.

Cleaned the heads (gently!) with rubbing alcohol.

Still "Not Ready."

By aclband1t

Rookie (22)

aclband1t's picture

24-10-2018, 02:41

Modified my SFD-321B per this article, then installed it:
http://jope.fi/drives/sfd321b/

Results are now highly-consistent:
* 'call format' for either size tries to format the disk, then eventually fails with 'disk error'
* 'files' on a disk that is formatted correctly and contains data gives 'disk I/O error'

It doesn't seem to be spinning quite as fast as I'd expect, though that's certainly not objective. I'll check voltages on this one, too, and see what I come up with.

By aclband1t

Rookie (22)

aclband1t's picture

04-11-2018, 15:34

Finished the disassembly of the unit today (main PCB removed). There doesn't appear to be any capacitor leakage, so that's very lucky. Seems like the CR2032 was replaced at some point, but I don't see anything else that has been.

At a loss for what to do next, though, for the FDD. If, indeed, it could even have been related to leaky caps...




By Alexey

Guardian (1718)

Alexey's picture

04-11-2018, 20:08

I had a similar issue with my Sony computer. The drive didn't read or write anything. The reason was in a missing READY signal, as you can see on this image from the analyzer:

AFAIK in Sony computers if the drive doesn't produce the READY signal, the board will ignore all read data. On the referenced above image the READY signal should go low after 2 seconds together with DS0, but it doesn't. So the data from the RDATA pin that was successfully acquired was just ignored and I was getting a "Not ready" error. Try to see what happens on the READY pin of the drive when you try to read the diskette.

Also, I see that your caps on the video board are most likely dead (leaked long time ago). The corrosion on some solder points is clearly visible. If I were you, I would replace them, especially if the composite video quality is poor.

By aclband1t

Rookie (22)

aclband1t's picture

05-11-2018, 10:59

I can check it, but I don't think that the READY signal is the issue -- the error I'm getting on the new drive is not "Not ready," but rather "Disk Error" (when formatting) or "I/O Error" (when issuing, for example, the "files" command). With the old/original drive, the results are entirely inconsistent, so I'm thinking I'll only work with the new drive (since it's highly consistent) before trying to figure out the old one.

Also, will definitely be replacing the caps on the daughterboard. My point was that it doesn't look as bad as some of the other photos I've seen of the Sony units -- some of those are absolutely wrecked. I think you're right after all that there's corrosion of the solder points, but it seems to be pretty localized.

The composite video seems to be fine. The audio is a bit quiet (as expected with the original capacitors, as I understand it).

Page 2/3
1 | | 3
My MSX profile