First, make sure if the drive really needs head alignment before touching anything, it is a very delicate procedure that needs a lot of precision. Usually the symptom of bad alignment will be floppies that can be formatted and read correctly on the suspect drive but won't work with other (properly aligned) drives. Try to discard easier stuff to fix first, like poor lubrication, stuck heads, zero track sensor, and so on.

If you are REALLY sure that it has alignment issues: the proper way to align the heads requires a special disk, an oscilloscope and a service manual describing the procedure, test points and all that. Since I assume you don't have all those things (the alignment disks in particular are quite rare) you can achieve a "good enough" alignment using the ImageDisk software: it has a special function that allows you to check the alignment by manually stepping to different tracks.

The general idea is to use a disk that has been formatted in a properly aligned drive (a commercial disk would be the best for this) and run the alignment function of ImageDisk. Step through the different tracks, make sure each track is identified correctly and that you get no read errors. Otherwise, correct the position of the heads by moving them *very slightly* forwards or backwards... the way to do this varies from drive to drive, but it usually requires loosening one or two screws in a way that allows you to move the head assembly. Again, note that even moving the heads 1mm can throw things out of whack, it requires very precise movements.

Once you get 100% correct reads move to other tracks and check again (I usually do it in steps of 10 or so). You'll probably need to correct the position again, then go back and further adjust the position. You can tighten back the screw when all the tracks read correctly, and check again as tightening the screws may also affect things. It can be an infuriating process.

Finally, test with other commercial disks if you have them, and try to format blank disks on the newly aligned drive to see if they read correctly on other drives.

thanks for the information that's great to know I'm pretty Shure the heads need aligning so will give it a try
regards jude

Agreed that you shouldn't even try to align a drive unless you are SURE it's
faulty. Strongly recomment using my ImageDisk tool to see how far off it is
from disks formatted on other drives first!

Aligning a drive is precicely adjusting it's head positions to be exactly
where it should be track-to-track.

To do this properly, you need a special (and virtually impossible to find these
days) "alignment disk" - which has been manufactured to very close tolerances
to have it's track in the right positions, and also has a bit-pattern which is
recognizable on a scope.

note: Once you have written a disk, it becomes "mostly" aligned to the drive
it was written on (I say "mostly" because if written on a misalighed drive,
edges of the original tracks may renaub).

If you don't have a proper alignment disk, the best you can do is to try and
find a disk of known good alignment. I've found commercial software from
reputable companies big enough to have their disks bulk manufactured to be
pretty good. Bulk software makers tended to keep their drives in good alignment.

Failing that, format a new/bulk-erased disk on a known good alignemt drive.
Since new drives are rare these days, finding a good aligment drive can be
tricky - you need one you've not had read errors with reading disks from other
drives. In the end, you may just have to decide which of your drives you want
to adjusted one to closely match.

My ImageDisk tool has an "A)lignment/Test" function which can help you get
pretty close to the center track position of the disk you use to tests.
- basically it will read the dis producing a tone of higher pitch the more
sectors it can successfully read on a track - Near the center track, you can
adjust the head position in both directions to find the "edges" of where all
sectors could be read, then position it in the center of that range - repeat
in other cylinder positions near inner/out ends and find the best match.

Aligning the heads individually is tricker, you have to not affect one while
doing the other...

Much more information/detail is in the ImageDisk documentation.

thanks for the imfomatio9n dave will have a look at the imagedisk software

Dave, one issue with IMGDisk's alignment tool is that it starts by automatically analysing the first track to identify disk type. On a working drive, this works.. on a misaligned drive it is very possible that track 0 is unreadable (or any other track even). In this case the user can't go into the beep routine. Instead, he'll need to adjust the head position blindly then hit reanalyze in hopes that IMD now recognizes the format.

For these cases, can the format be dictated by the user such that the alignment tool immediatelly tries to read the sectors according to the provided format without the need for track analysis?

I'll look into it, it has been years since I've gotten much into the low-level details of IMD.

Obviously you wouldn't do this on an actual alignment disk, but one possible work-around, full format a new disk on a "good"
drive, then format the first couple of tracks on the misaligned drive (with IMD you can format as few tracks as you want) that
should be able to get you past the analysis phase, then align "deeper in", to access the tracks made on the known good drive.

This should at least get you aligned enough that you could then align to a commercial product disk without having to write to it.

Yes, that's a nice workaround 👍

wbahnassi wrote on Today, 02:06:

Yes, that's a nice workaround 👍

I should probably add this "trick" to the documents.

IMD wasn't designed with the idea of aligning disks .. it was designed to be able to read anything that the PC FDC hardware was capable of - it uses it's own low-level drivers as it accesses the FDC is some more unusual ways - (It doesn't use DOS or BIOS - it talks directly to the FDC - in fact, I have drive B: set to NONE on my primary IMD machine - that way I don't have to worry about BIOS getting upset when I have a non-PC drive attached)

- ALign was just a "feature" I added later.

Anyway, as part of the low-level drivers, it performs an analyze to "figure out" some characteristics of the disk it's dealing with...
Changing/Bypassing this would probably require a fair bit of redesign - not something I'm real keen on doing now (This is the first complaint about it I've gotten in 20 years!)