I've had a similar issue. Sometime setting write protect on the disk allows it not to occur again.

No idea really. Got a gotek. I assume the floppys are just bad.

I don't really mind waiting for disks to load, but switching disks is really a pain.. Maybe I'll pick up an extra drive instead but if I suffer through this a bit the upgrade will be more rewarding.
😁

I think people use powerful magnets to wipe disks in these situations. Those stronk HDD magnets are good for this apparently.

Joakim wrote on 2022-04-12, 05:28:

I was wondering if anyone has experience in attempting to 'reset' the magnetisation of the disks with a degausser?

I do it with strong permanent magnet. Any modern magnet will do in most cases, I use neodymium one from a broken HDD but a magnet from a speaker would work as well. It has to be strong enough for the field to reach the floppy surface throuth the envelope. There is no need to touch the actual magnetic surface and risk any mechanical damage to it. With 3.5" floppies it is preferable to remove the shutter to avoid any chance of it getting magnetized - though this should not happen with electromagnet running on AC voltage. With a permanent magnet (or DC electromagnet) you have to move it over the surface of the floppy as if you were erasing it with a rubber - this will create enough chaotic changes in the floppy material to render it demagnetized as far as the drive heads are concerned. So it doesn't need to be a perfect. You don't have to move AC electromagnet around (or the floppy) unless it's field is too narrow to erase entire floppy sufrace.

In either case (permanent or electromagnet) it is a good idea to reduce the field slowly, to avoid leaving any part of the floppy in one particual magnetic state. If that happens you might get R/W errors and will have to repeat the process, properly this time. The easiest way to reduce the magnetic field is simply to increase the distance - just pull it away slowly (2cm/s or so). This is more difficult with permanent magnet but on the other hand it's also not that critical - I'm just mentioning it as a good practice and so that you don't give up if it doesn't work right away, the device you have access too might require a certain approach to get best results. I would worry about the shutter residual field more than the floppy surface.

Deunan wrote on 2022-04-12, 19:23:

Joakim wrote on 2022-04-12, 05:28:

I was wondering if anyone has experience in attempting to 'reset' the magnetisation of the disks with a degausser?

I do it with strong permanent magnet. Any modern magnet will do in most cases, I use neodymium one from a broken HDD but a magnet from a speaker would work as well. It has to be strong enough for the field to reach the floppy surface throuth the envelope. There is no need to touch the actual magnetic surface and risk any mechanical damage to it. With 3.5" floppies it is preferable to remove the shutter to avoid any chance of it getting magnetized - though this should not happen with electromagnet running on AC voltage. With a permanent magnet (or DC electromagnet) you have to move it over the surface of the floppy as if you were erasing it with a rubber - this will create enough chaotic changes in the floppy material to render it demagnetized as far as the drive heads are concerned. So it doesn't need to be a perfect. You don't have to move AC electromagnet around (or the floppy) unless it's field is too narrow to erase entire floppy sufrace.

In either case (permanent or electromagnet) it is a good idea to reduce the field slowly, to avoid leaving any part of the floppy in one particual magnetic state. If that happens you might get R/W errors and will have to repeat the process, properly this time. The easiest way to reduce the magnetic field is simply to increase the distance - just pull it away slowly (2cm/s or so). This is more difficult with permanent magnet but on the other hand it's also not that critical - I'm just mentioning it as a good practice and so that you don't give up if it doesn't work right away, the device you have access too might require a certain approach to get best results. I would worry about the shutter residual field more than the floppy surface.

Yeah ok I was considering doing this but I also read that some people think very strong magnets create a magnetic polarization that is hard for a drive to erase. But I get what you mean, also I doubt it is possible to do any permanent damage.

I accidently broke my workbench installation though without having any back ups so I need to wait for an adapter to get this baby going again through winuae and try your technique.

Oh and look at this fella who built a 'physical' degausser:
https://youtu.be/bKNigMT0qq4

I wonder if this might work for reviving dead floppies too (not that I particularly need to).

I've got a couple of cases of brand new floppies but they're just a cheap brand (Melody) so its not uncommon for there to be a few bad ones in a pack of 25. There doesn't seem to be anything physically wrong with the bad ones (media looks fine) but writing an image to them will fail, a surface scan will turn up bad sectors, etc. Norton Disk Doctor and reformatting doesn't recover them but perhaps wiping them completely with a degausser or magnet and starting over would work.

Depends on how dead the floppy is - I've "repaired" quite a few floppies with my magnet. Sometimes it takes a few tries to get rid of all bad sectors but if it still fails to format on particular % of progress after 3-4 times then you have a damaged surface and that's it. If it's a pre-owned floppy and is dirty, cleaning the surface first might help (and surely will help avoid any head damage). Since NOS DD floppies can be expensive I've bought some old, used ones and so far had a pretty good track record of getting them to work. The ones that ended up with permanent bad sectors can be sometimes used and 1-sided floppies (for DOS 1.x or C64), and/or as head protectors during transport or to test newly obtained drives in unknown condition. So I keep them around.

BTW a good demagnetizing pass can also scrub a 5.25" HD floppy to be used as DD one (with just 40 tracks written to it with double stepping on HD drive). It has a very good chance to read properly in DD drives. A strong, well working DD drive can even sometimes write to scrubbed HD floppy as well, but only once, so even formatting will fail because the moment heads try to over-write first sectors with FAT structures it'll all go sideways.

The default DOS FORMAT needs a /U to tell it to "really" format.
One of the alternatives, not sure if it's NFORMAT or FDFORMAT, can also do a 2 pass whole disk format, whole disk verify (which may pick out problems with drives not tracking reliably)

A permanent magnet strong enough to wipe the disk, would leave it harder for the drive to write as the disk would be fully magnetised

Matth79 wrote on 2022-04-13, 23:13:

A permanent magnet strong enough to wipe the disk, would leave it harder for the drive to write as the disk would be fully magnetised

This where the concept of degaussing comes in. The point is to remove all magnetisation, not create a new maybe stronger magnetisation.

That's why the field strength needs to be slowly decreased, or faded out, to prevent leaving any areas with one particular magnetic orientation. That being said, you can always repeat the process (as many times as you want/need) if R/W to scrubbed floppy fails, and frankly it's rather hard to create any problematic hot-spots anyway. The media will simply not accept magnetization over certain threshold, and the heads should be able to deal with it.

The whole idea of scrubbing the media is meant to resolve 2 issues:
1) Remove any readable data that can prevent FDC (or the OS) from formatting the floppy properly. DOS in particular can be pretty stubborn and stupid about it - like refusing to format only 1 side, or the opposite, silently formatting only side 0 if the previous format was such, even on 2-sided DD floppy in standard 360k PC drive, even if using /U. Or just refusing to format at all if it doesn't like something about track 0 residual data.
2) Remove any weird and unreachable magnetic glitches that prevent correct operation or cause bad sectors - for example if the floppy was written to by unaligned drive and now has fresh, strong data in what should be space between the tracks, it can easily prevent some weaker drives from being able to read or write to such floppy. Even normal use in just one drive can create some bit glitches that the FDC can't deal with (most HW has some requirements about sector gaps and fill bytes).

TL;DR: Keep your magnets well away from floppies you do not want erased. On the other hand, if you want a floppy properly scrubbed from any data, a simple magnet will do the job. Might take some practice though.

I did some test yesterday but normal refrigerator magnets just aren't enough. I might take apart and salvage some magnets from an otherwise unreliable hard drive that was once in one of those dell gx something pentium 4 machines. Bet the hard drive is well done after living in one if those furnaces 🤣.

Deunan wrote on 2022-04-12, 19:23:

If that happens you might get R/W errors and will have to repeat the process, properly this time. The easiest way to reduce the magnetic field is simply to increase the distance - just pull it away slowly (2cm/s or so).

That's not enough.
You also have to reverse the pole of the magnet while increasing the distance.
That's why degaussers are fed with AC. The field switches 50 times per second and you can focus on increasing the distance slowly

I killed an old harddrive and I have two nice and strong magnets. I put the two magnets on a drill with opposite poles. This make shift degausser can destroy floppies alright but it does not seem to fix the bad ones. According to x-copy (on Amiga) they are bad in the beginning of side 2. Maybe if I try to format them for pc and run checkdisk or something.

You can use Image Disk (IMD) for DOS to force a format of any disk that DOS's FORMAT command will balk at. No need to degauss anything. Of course, physically damaged or degraded disks will not be saved by either.

maxtherabbit wrote on 2022-04-17, 18:56:

You can use Image Disk (IMD) for DOS to force a format of any disk that DOS's FORMAT command will balk at. No need to degauss anything. Of course, physically damaged or degraded disks will not be saved by either.

Sorry if I misunderstand you as English is not my first language. Are you suggesting that I grab ahold of an image of a empty formatted Amiga disk and write it in ImageDisk on a PC?

Iv had the worst luck with floppy disks and drives. Sometimes they work one day, then die the next. Or die then decide to come back once or twice. Iv had drives die the minute i open them to clean the heads. Pretty sure at this point iv had drives die just from looking at them incorrectly.

Tis why i mostly stick to collecting CD releases. Kinda a sucker for those big 5.25 floppies though.

Joakim wrote on 2022-04-17, 20:14:

maxtherabbit wrote on 2022-04-17, 18:56:

You can use Image Disk (IMD) for DOS to force a format of any disk that DOS's FORMAT command will balk at. No need to degauss anything. Of course, physically damaged or degraded disks will not be saved by either.

Sorry if I misunderstand you as English is not my first language. Are you suggesting that I grab ahold of an image of a empty formatted Amiga disk and write it in ImageDisk on a PC?

You don't even need an image file. IMD has a format function. It literally just formats the disk though, does not write a boot sector or filesystem.

FioGermi wrote on 2022-04-17, 21:25:

Iv had the worst luck with floppy disks and drives. Sometimes they work one day, then die the next. Or die then decide to come back once or twice. Iv had drives die the minute i open them to clean the heads. Pretty sure at this point iv had drives die just from looking at them incorrectly.

Tis why i mostly stick to collecting CD releases. Kinda a sucker for those big 5.25 floppies though.

Well yeah it is not the most reliable format. Personally I never had a drive fail ok me though. In both cases they are still plenty so grab an other disk and move on (this thread is just me being stubborn).

The sad thing is perhaps original games on floppies, as they will fail at some point in a not so distant future.

maxtherabbit wrote on 2022-04-17, 21:42:

Joakim wrote on 2022-04-17, 20:14:

maxtherabbit wrote on 2022-04-17, 18:56:

You can use Image Disk (IMD) for DOS to force a format of any disk that DOS's FORMAT command will balk at. No need to degauss anything. Of course, physically damaged or degraded disks will not be saved by either.

Sorry if I misunderstand you as English is not my first language. Are you suggesting that I grab ahold of an image of a empty formatted Amiga disk and write it in ImageDisk on a PC?

You don't even need an image file. IMD has a format function. It literally just formats the disk though, does not write a boot sector or filesystem.

A very cool program, ImageDisk, I tried erase method, it did not improve the results, or even made it slightly worse. Maybe I configured it incorrectly or the disk is just deteriorating.