Alignment diskette (P/N 090-0004)

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hackerb9's picture
Last seen: 10 months 6 days ago
Joined: Sep 13 2005 - 08:35
Posts: 17
Alignment diskette (P/N 090-0004)

I'm following along with the Apple Service Level 1 Technical Procedures manual that describes how to test a Disk II analog board. However, when I get to step C, Azimuth Test — see images below — I'm stuck because it  requires the Alignment Diskette (Apple part number 090-0004).

  • Does anyone know where to get such a disk? Given that there isn't an image of it on, it appears unobtainable.
  • Is this something that I'd need to create on a non-Apple computer? I wouldn't think so, but then I don't know the intricacies of testing the azimuth.
  • Is anyone able to tell from the oscilloscope patterns what data Apple had written to the disk? It appears to be extremely repetitive and identical on every track.

Thank in advance for any help or ideas you might have!



By the way, for anyone who is looking for the main testing disk used in the service manual, Disk Alignment Aid diskette (P/N 652-0199) is available at

tokabln's picture
Last seen: 6 months 5 days ago
Joined: Dec 30 2015 - 10:48
Posts: 253
You can't be sure that this

You can't be sure that this will work as expected.


If such image will be used, for example, on an already misaligned Floppy Drive to create such a test disk, the floppy can't be used to align other drives.

If you try to do so, all drive alignments will have the same misalignment as the floppy drive you used to create "your" testfloppy.


You need to use a fully and correct aligned floppy drive... which is something you want be able to do so with home equipment.

From my perspective, the image from is more or less useless as far as you didn't know that you have a correct aligned and working floppy drive.



Last seen: 1 week 16 hours ago
Joined: Apr 26 2016 - 08:36
Posts: 685
Don't bother with the

Don't bother with the alignment procedure.

You need original alignment diskettes which cost a fortune and are basically unicorns.


Instead use the excellent field-alignment technique thats part of APTEST.  It's the only alignment procedure that actually works without the use of alignment diskettes.

All you need are a few known-good disks, preferrably commercially produced ones that were compied using calibrated machines.


Anyway, if you're having aligment issues, APTEST will help a lot.  It can also make perfectly good drives totally useless if you screw it up, so be careful and read the included (inside the software) instructions carefully.

Last seen: 7 months 1 week ago
Joined: Nov 2 2022 - 01:03
Posts: 31
Do you where we could find

Do you where we could find APTEST or if it goes by any other names?  I found the APTEST manual  but haven't found the disk yet.  This might give me the chance to try to win the lotto with adjustments and get this reading my disks again.

Last seen: 7 months 1 week ago
Joined: Nov 2 2022 - 01:03
Posts: 31
APTEST link https://mirrors


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