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5 1/4 floppy drive jumper settings (Mitsubishi MF504C-318UG)

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First post, by thevdm

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Hi,

I have a 5 1/5 floppy drive that I would like to use in a 486 build that I'm working on.

The drive I have is a Mitusbish MF504C, 1.2M. When the computer posts and checks the floppy drives the head moves as expected and no errors are displayed. Once Dos has loaded, selecting drive B results in the flopy disk spinning but no movement from the head. After a moment Dos returns "Drive not ready".

The 5 1/4 drive is on the first position of the FDD cable (before the twist) and there is a 3.5 floppy drive in the second position (after the twist) - Because of this, I have removed the terminating resister pack and removed the link on the "TD" jumper.

Having tried many combinations and feeling a little out of my depth, can anyone confirm if the jumper settings are correct? I have owned this floppy drive for a few years now and have never seen it work.

floppy jumpers.jpg
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MF504C jumpers
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In the image above, I have highlighted the currently connected jumpers with a red box around the label.

Thank you in advance
Jim

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 6, by Horun

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This has the "initial" jumpered positions: http://minuszerodegrees.net/manuals/Mitsubish … ion%20Guide.pdf
DC for Disk Change needs be jumped, move from SR to DC. Here is an enlarged picture of default jumpers for MF504C

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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 6, by thevdm

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Hi Horun,

Thank you for your answer, I have moved the SR jumper to DC, unfortunately this made no difference to the behaviour of the drive.

Many thanks
Jim

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 3 of 6, by Horun

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Hmm So it passes a BIOS Seek test but does not come ready with a formatted disk in it ? maybe it does not like the controller or the drive has a sensor failure or other bad part.

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 6, by snufkin

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Does the indicator light turn on at all? And does it still turn on if you jumper IR?

I think IR sets it so that the LED only turns on if the drive is Ready, so if it stops coming on after you set IR then it might mean that the drive never becomes Ready. Index and Read data are both only sent when the drive is in the Ready state.

There's what looks like a fairly complete set of instructions for the 504B here: http://www.minuszerodegrees.net/manuals/Mitsu … ion%20Notes.pdf

Reply 6 of 6, by perhenden

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wondow wrote on 2021-11-10, 02:17:

Here is my configuration:

Many thanks! That got my two drives working!

For reference, in case it can help someone later, the jumpers on my MF504C-318M was originally set like below.

Drive marked with drive letter A (MF504C-318M -rev A):
HR, MM, MS, IR, DC - DS1 - SB

Drive marked with drive letter B (MF504C-318M -rev B):
IL, MS, IR, IU, SR - DS0, TD - SB

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