Atari ST floppy drives and their limitations

Troubles with your machine? Just want to speak about the latest improvements? This is the place!

Moderators: Mug UK, Zorro 2, spiny, Greenious, Moderator Team

Post Reply
tzok
Captain Atari
Captain Atari
Posts: 252
Joined: Fri Jun 30, 2017 7:22 pm
Location: Bielsko-Biala, PL
Contact:

Atari ST floppy drives and their limitations

Post by tzok »

I've recently bought an SONY MP-F11W-U0 floppy disk drive in an unknown condition for a good price (~12€). It looked almost brand new, but had difficulties in reading and writing disks, especially 11 sector/track. I have cleaned it, and replaced two electrolytic capacitors: on +5V rail (47uF/6.3V) and in motor board (10uF/50V). I've decided to replace them, not just add 10uF to each one like Exxos suggests. After removing them, I've tested them and they seemed to be fine, only the 47uF had high current leakage (which would probably cured itself when left under power for some time). The one on 5V rail I have replaced with a 47uF/25V, and the one on motor board with a MLCC 10uF/25V (I've tried to measure voltage across it, but found almost nothing there - just some HF hum with amplitude of ~100mV). Now the drive works (almost) perfect...

But the topic was not meant to be about the repair (IMHO cleaning would be enough). This drive is not able to access tracks 83 and 84, while my EPSON SMD-380 easily formats and access disks with 84 tracks. Is this normal for this drive?
User avatar
1st1
Atari Super Hero
Atari Super Hero
Posts: 889
Joined: Mon May 07, 2012 11:48 am

Re: Atari ST floppy drives and their limitations

Post by 1st1 »

Guaranteed is only 80 tracks, so you can be already happy with 82 tracks.
Power without the Price. It's not a bug. It's a feature. _/|\_ATARI

1040STFM in PC-Tower (PAK68/2, OvrScn, 4 MB, 1GB SCSI, CD-ROM...) * 3x Falcon 030 * 3x TT030 * many 260 /520/1040ST(F)(M)(+) * 520/1040STE * many Mega ST * 2x Mega STE * Stacy * STBook * 2x SLM605 * 3x SLM804 * SMM804 * SH 204/205 * Megafile 30/44/60 * SF314 * SF354 * 5x Pofo * PC3 * ...
User avatar
1024MAK
Atari Super Hero
Atari Super Hero
Posts: 652
Joined: Sat Aug 01, 2009 2:58 am
Location: Looking forward to summer time in Somerset, UK...

Re: Atari ST floppy drives and their limitations

Post by 1024MAK »

Yes, all 80 track 3.5" drives are, err, designed for 80 tracks...

Some can manage 81, 82, 83 or if you are really lucky, 84. But all that is happening, is you are taking advantage of an engineering tolerance.

Mark
Falcon, Atari 520ST, 520STFM, 1040STE, Mega, TT and more PC's than I care to count and an assortment of 8 bit micros (nearly forgot the Psion's).
Visit the Atari-Forum Wiki. Lots of technical info at DrCoolZic Atari ST Site :D
tzok
Captain Atari
Captain Atari
Posts: 252
Joined: Fri Jun 30, 2017 7:22 pm
Location: Bielsko-Biala, PL
Contact:

Re: Atari ST floppy drives and their limitations

Post by tzok »

Yes, but have anyone tested floppy drives used in various Atari ST, for how many tracks they support? After all, I think that each Epson SMD-380 will do 84 tracks.
tzok
Captain Atari
Captain Atari
Posts: 252
Joined: Fri Jun 30, 2017 7:22 pm
Location: Bielsko-Biala, PL
Contact:

Re: Atari ST floppy drives and their limitations

Post by tzok »

So far I've checked the following:
EPSON SMD-380: 84 tracks,
CHINON FB-354AA: 84 tracks,
NEWTRONICS D357: 84 tracks,
SONY MP-F11W-U0: 82 tracks.

Is there any list of FDDs used in the ST computers?
ijor
Hardware Guru
Hardware Guru
Posts: 4061
Joined: Sat May 29, 2004 7:52 pm
Contact:

Re: Atari ST floppy drives and their limitations

Post by ijor »

I don't think anybody made a spreadsheet of tracks per brand and model, if that's what you mean. It wouldn't be perfectly accurate because models aren't always 100% identical. It is perfectly possible that a particular unit might support a different number of tracks than a different unit with the exact same model.

I believe most Atari branded drives do support 82 tracks. Some, of course, more. Some original disks require 81 or 82 tracks, IIRC only a couple use 83 tracks.
rcamp48
Captain Atari
Captain Atari
Posts: 176
Joined: Wed Feb 21, 2018 8:03 am

Re: Atari ST floppy drives and their limitations

Post by rcamp48 »

My modified Sony MFP 920 does 11 sectors 86 tracks 2 sides reliably, unfortunately, I only have one but I have 2 spare ALPS drives all modified and set up for use on the Atari ST, do I have to modify the jumper to ds0 for an external drive on the Atari ST, and if anyone has an empty case that they want to sell with the power supply and cable I will trade a couple of modified ALPS floppy drives for just that. Maybe I can get a few Sony MFP 920 drives from my computer dealer. He only charges $5.00 Can for them. Russ
Now supporting Atari Portfolio , my archives are still being maintained.
BBS is now up again as an Atari BBS, run on PC, cause I sold everything but my Atari Portfolio.
Note: Atari Portfolio IDE CF kits are being made. Get yours today! :megaphone:
Note that my BBS is back online with Win-server 8.0454.8 at telnet://spyvisitsspybbs.com:1990 and http://www.spyvisitsspybbs.com:1991
Post Reply

Return to “Hardware”