Classic floppy drive alignment

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CWJ_Wilko's picture
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First time in the world of the classic Macintosh, I have a Macintosh Classic with the SuperDrive (1.44mb).

I did a lot of work to make the auto eject mechanism functional again, but I have somehow managed to cause more problems. Previously, I was able to read and write to floppies that were initlialised on the Classic in a USB floppy drive attached to my iMac (also tried with PC software WinImage). Now, they are completely unreadable, except when used on the Classic, where they work fine.

I have been using brand new disks, so am ruling them out. If I format a brand new disk on WinImage with System 7 software, the Classic won't read it. If I use a disk I initialised on the Classic, and reformat it in WinImage, the Classic only sees the previous volume label of the disk - still works, as if it were never reformatted! Reformatting old disks on WinImage results in a track/head error, unless I also specify an image to write to it (System 7 software).

I assumed this was a head alignment issue, but I've tried everything (without having an oscilloscope) to get it readable again outside the Classic, with no luck. Is there something I am missing? By physically manipulating the head and disk, I was able to force the Mac Classic to read the correct volume label just once - and got an error message straight away. I have cleaned the heads repeatedly, again they work fine with disks initialised on the Classic.

I'm willing to buy a new used drive at this point, pulling my hair out. Unless there is something I am missing.

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Re: Classic floppy drive alignment

When you format a disk on the Classic, it sees 800K or 1.44M?

I ask because the PC will only read/write the 1.44M format. Perhaps you've broken or disconnected the HD sensor so it only works now as 800K...

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Peter Rittwage
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CWJ_Wilko's picture
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Re: Classic floppy drive alignment

It's 1.44mb, and according to the Finder it sees 1.4mb (which I believe is normal). I should try read and write to the entire disk to confirm that its working as advertised, might do that today.

I guess I should also not rule out the USB floppy drive that I am using, it is definitely not new, although it reads and writes IBM formatted disks just fine.

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Re: Classic floppy drive alignment

Well, darn. So much for an easy explanation. Sad

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Peter Rittwage
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CWJ_Wilko's picture
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Re: Classic floppy drive alignment

No luck. It can definitely read and write to the full 1.4mb. It briefly was able to read the header again today but then gave up with an error message.

Add expletives here. It's been three days and I'm dumbstruck by how bad these drives are. After repairing several Disk ][ drives with a bit of patience and skill, I feel like I'm qualified to say that these Macintosh drives were Apple's (Sony's?) first attempt design components that should be thrown away, and not repaired. The mechanisms are so extremely complex and the entire thing feels so fragile. They're just awful.

I can adjust the heads any which way, and they will still read and write disks that were initialised on the Macintosh, same with the track stepper motor, it doesn't matter. I'm perplexed and out of options.

Does anyone want to sell me a drive? I'm looking for the MP-F75W-01G and its variants. 2mb SuperDrive.

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Re: Classic floppy drive alignment

You're positive the PC drive is OK? I have a few USB 3.5" drives, and they are all out of alignment with each other...

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Peter Rittwage
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CWJ_Wilko's picture
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Re: Classic floppy drive alignment

I don't have a third drive to doubly make sure, but I believe it to be good. Ill try follow this up.

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Re: Classic floppy drive alignment

I've had frustrating experiences trying to align 80-track drives, even with a scope.

I've got two TM-100-4's that will read and write each others' disks perfectly, but only one will read disks from my more "modern" PC 5.25" drive. It makes no sense at all, but that's what happens.

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speedyG's picture
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Joined: Nov 16 2011
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Re: Classic floppy drive alignment

Hello to all reading this thread.....

one thing is that most people reading my site about Disk II
end at the first page about trackalignment and don't read ahead till:
http://www.appleii-box.de/H084_4_AppleIIDiskService4.htm

otherwise they would have recognized that at the first graphic in top i explain:
the trackwidth at a caassetterecorder is 0,6 mm
while at the Disk II the trackwidth is only 0,08 mm
and at a 80 track drive the trackwidth is only 0,025 mm !

Another problem is that in the early 80 track drives they still used for
headpositioning simple steelband.... the use of special alloy to compensate
better the scaledrift ( temperature coefficient ) of the positioning steelband
was put into the market first after 3 to 4 years of collecting bad experiences....

and next problem was that in the early days the lightbarriers used for
indication of track zero have not been very precise....

That are a bunch of reasons that for nearly 4 to 6 years of the early 80 trackdrives
had a large tolerance among each other....

I will add another page in this year to the diskpages at my site about that topic....

sincerely
speedyG

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Re: Classic floppy drive alignment

There is a black colored part on these old Sony 3.5 drives that when moved, changes the drive in such a way so that disks can only be used in that drive only.

Now, about the attempt to fix the eject mechanism, those parts within themselves have no effect on readability.

The only part which is the most significant on those drives is the head.

A lot of people, when fixing those drives they force the head open too wide and mess it up when any cleaning of the head is performed.

Another thing which is overlooked when people fix those drives are the bearings.

They often get clogged up.

They must move freely.

CWJ_Wilko's picture
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Re: Classic floppy drive alignment

Just wanted to mention that a member of the forum was able to ship me another drive, and everything is now working well. One of the floppy disks has been permanently damaged from all the earlier problems, but I have plenty of other disks that are now initialising and readable on the USB floppy drive.

A success story.