5.25 floppy drive jumpers \ VOGONS

5.25 floppy drive jumpers

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First post, by thevdm

Posted on 2020-08-15, 14:17

thevdm Offline

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Location: Kent, UK

Hi all,

I have been trying to get a 5.25 floppy drive working on a 486 PC and am not sure if there is an issue with the drive (possibly not finding track 0). The drive appears to be a 1.2MB drive as selecting 360k in the BIOS gives a mismatch error.

For context, the setup is:
* 1.44MB 3.5" drive as drive A (after the twist)
* 1.2MB 5.25" drive as drive B (before the twist) <-The drive this thread is about

I have tried multiple combinations of switching between MM/MS, DS0/DS1/DS2 (DS1 appears to be the correct one to use from my research)

What does the drive do:
* The head seeks at boot, drive A seeks, then this drive seeks (as expected)
* When trying to access B: from DOS the light comes on, the head judders a tiny amount then DOS shows an error.
* I did notice that if the drive didn't always park the head back at the start but this seems to be parking in the correct place now (maybe the LED/sensor is dead)
* When a disk is inserted, the drive spins up
* I've done the usual head clean, clean and re-lube rails etc...

These are the jumper settings I have

What would your recommendations be?

Gaming rig: Dell Dimension XPS T500 - PIII 500 - 288MB RAM - Voodoo3 3000 - SoundBlaster Live! Value - DVD-ROM - CD-RW - 3.5" 1.44 - 98SE & 2000 dual boot
A nostalgic pile of laptops from the late 80's to late 90s.

Reply 1 of 5, by Horun

Posted on 2020-08-15, 19:32

Horun Offline

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What make and model is that 5.25" floppy ?

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 2 of 5, by thevdm

Posted on 2020-08-15, 20:00

thevdm Offline

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Location: Kent, UK

Hi Horun,

It would appear to be a Mitsubishi MF504C-318 UG . The motor has a label on it for Mitsubishi U288Y073 as well as JVC AA01JF, the PCB on the top has the code MDK 3IIV-O.

Hopefully that is helpful.

Jim

Reply 3 of 5, by Horun

Posted on 2020-08-15, 22:02

Horun Offline

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Here is the manual for it plus a jumper layout picture for hookup to standard AT class computers. It appears yours has IU jumped which the default is open.

Attachments

Filename

Mitsubishi - MF501C and MF504C_Guide.zip

File size

146.14 KiB

Downloads

251 downloads

File license

Public domain

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 4 of 5, by hwh

Posted on 2020-08-16, 03:46

hwh Offline

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Location: Eugene, OR

I've never changed jumpers on a floppy in my life.

I read the descriptions for the jumpers and I don't even know what any of them mean. "Drive select?" "1MB?" "Standard ready signal?" "Motor start with motor on?"
What the hell?

Reply 5 of 5, by thevdm

Posted on 2020-08-16, 09:52

thevdm Offline

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Posts: 41
Joined: 2018-03-12, 18:48
Location: Kent, UK

Thank you for the manual and image Horun, I have tried the drive with the IU jumper removed, then also with the TD and terminator resistor pack removed in case that's not required with the 3.5" floppy drive that's installed too. Unfortunately still no joy. On closer inspection there appears to be a ceramic capacitor with a chunk broken off, following the traces it goes to the connector that goes to the heads - I wonder if this is stopping the heads from being able to read anything. Looks like I might have to do some recapping on the drive.

The error that comes up in DOS is the "Disk not ready" one which implies it's not detecting the disk, although when I put a disk in the drive the motor spins up implying that it can detect that something is there.

kwh - The more modern 5.25 floppy drives are much more simple, just plug it in and go, if the prices weren't so ridiculous on ebay I'd buy one of them.

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