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5.25" Floppy Disk Drives and Motor On Signal (spindle won't start)

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First post, by MMaximus

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I recently bought a used Panasonic JU-455-7AAG 360Kb floppy drive - It was listed as untested but after lubricating the rails and cleaning the heads it seems to be in good mechanical condition.

The drive initializes at boot, the LED lights up and it can boot to a DOS floppy. However when trying to access the drive, the LED lights up but the spindle won't start. A DIR command makes the system hang before giving the "drive not ready error". If I type "DIR" and quickly insert the floppy then put the lever down, the disk reads because inserting a new disk makes the spindle move temporarily.

I tested with another 360k drive (Matsushita JA-551-017) and It displays the exact same behaviour. OTOH A 1.2M drive (TEAC FD-55GFR) works fine in the same machine.

I'm using a MIO-AT controller card in a 386 PC.

I've read that some controller cards can't output enough power to drive the spindle of a 360Kb drive. Does anyone know anything about this?

SXQ4gOWl.jpg

Hard Disk Sounds

Reply 1 of 4, by derSammler

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Make sure the jumpers are set correctly. Motor on is used differently in a PC and the jumpers may not be as they should, depending on where this drive was installed before.

Reply 2 of 4, by Horun

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derSammler wrote on 2020-03-21, 16:05:

Make sure the jumpers are set correctly. Motor on is used differently in a PC and the jumpers may not be as they should, depending on where this drive was installed before.

Exactly ! Many Amiga's, Amstrad's, Commadore's and some others use different floppy jumper settings. I have an old Compaq board and it requires the drives jumpered at DS0 not standard DS1 and uses a proprietary cable.

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 3 of 4, by MMaximus

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I've done further testing in a single drive configuration, with the 5.25" drive being connected after the twist. The drive seems to work but only occasionally. Sometimes I'll type A: to access it and the LED will just light up and hang there, with the spindle not turning. Then I reset the drive by flipping the lever off and on, and it makes the spindle turn and the drive work again for a bit. It's almost as if it were stalling like a car that's running low on petrol.

I've used the same jumper settings for the Matsushita and it seems to work more consistently but sometimes exhibits this problem... which makes me believe it might be the controller card?

Here are the jumper settings on the drive:

VQQx8Hzl.jpg

I'm using the recommended jumper settings from a PDF found online:

DS1 Drive selected as DRIVE 1 OFF
DS2 Drive selected as DRIVE 2 ON
DS3 Drive selected as DRIVE 3 OFF
DS4 Drive selected as DRIVE 4 OFF
MX Drive selected permanently OFF
MM Drive motor enabled by the Motor On signal ON
MS Drive motor enabled by the Drive Select signal OFF
UA Front LED handled by the In Use signal OFF
DA Front LED handled by the Drive Select signal ON
RY PC XT-AT compatibility OFF
TM Terminator ON

Hard Disk Sounds

Reply 4 of 4, by maxtherabbit

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MMaximus wrote:

I've read that some controller cards can't output enough power to drive the spindle of a 360Kb drive. Does anyone know anything about this?

That's nonsense. The spindle motor gets its power directly from the molex. The controller only sends a logic level signal to turn it on or off

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