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Old 23 May 2017, 20:07   #1
imqqmi
 
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Floppy disk Repairing floppy disk video

Something that I came across when recovering my floppy disks is that some disk donuts got separated from the metal hub. At first I thought the disks were a total loss until I developed a way to fully recover them. It's a two step process:
  1. Glue the donut back to the metal hub
  2. Capture the disk using a modified floppy drive where the drive head is controlled by FloppyControlApp using microstepping. This allows smaller steps to be taken and fully recover all data.
Read more about it on my blog:
http://www.makercentral.net/pages/po...etal-hub-9.php


See this video for the whole process:
[ Show youtube player ]


Here's a video about properly cleaning floppy disks. I've been able to read very dirty, fungus infested disks by using this cleaning method. I've designed an 3D printable cleaning kit to help in the process.
[ Show youtube player ]


I hope you find these videos useful!
 
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Old 24 May 2017, 03:09   #2
prowler
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This is an interesting development...

I have some floppy disks which have become separated from the metal hub. I bought some glue with which to reassemble them, but have hesitated to go ahead because I wasn't sure whether it would be possible to restore the concentricity of the recorded tracks with sufficient accuracy to allow recovery of the data.

Your endeavours demonstrate that this is indeed possible!
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Old 25 May 2017, 15:29   #3
imqqmi
 
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If you need any help recovering your disks, please let me know, I'd be glad to help out.
 
Old 26 May 2017, 03:54   #4
prowler
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It should be straightforward enough to recover Amiga floppies once the disks have been cemented to the hub, but it will surely more difficult to read the data from PC floppies without specialist equipment, unless the index mark for each track is restored to exactly the same position as previously relative to the reference hole in the hub.

This is not necessary with Amiga floppies, of course, because the index mark is positioned randomly.
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Old 26 May 2017, 10:31   #5
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http://www.makercentral.net/media/Cl...leaningKit.zip

file for 3d printer
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Old 26 May 2017, 11:52   #6
imqqmi
 
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Floppy disk

Quote:
Originally Posted by prowler View Post
It should be straightforward enough to recover Amiga floppies once the disks have been cemented to the hub, but it will surely more difficult to read the data from PC floppies without specialist equipment, unless the index mark for each track is restored to exactly the same position as previously relative to the reference hole in the hub.

This is not necessary with Amiga floppies, of course, because the index mark is positioned randomly.
That is only a small part of the problem. If the disk is off center, no system, be it PC or Amiga, will read the disk correctly. Tracks will look like this to the system, see the image below. But you're correct that the problem is bigger for systems depending on an index signal.

  1. The system will see some wrong tracks/sectors on the expected track
  2. The system will not be able to read the sector where there's noise (which is the noise between the tracks).
  3. The system will not be able to reassemble the correct tracks/sectors as a track on the Amiga is decoded as a whole, not sector by sector.

Last edited by imqqmi; 26 May 2017 at 11:57.
 
Old 26 May 2017, 12:11   #7
imqqmi
 
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Floppy disk

To be able to recover such disks you'll need:
  1. Microstepping to reach the sectors otherwise covered by noise between the tracks.
  2. Software that reassembles the disk using the sectors headers, which contains track and sector information, which FloppyControlApp does from the beginning, even before it could use microstepping.
I'm not sure Kryoflux or SCP are capable of doing so, to my understanding they keep retrying until the entire track is read 100%, but ignore good sectors if there's one bad one on the same track basically. This is good from an archival stand point, but not so good for data recovery. I know Kryoflux also has advanced analysis software but I couldn't find details about the features it provides. If anyone knows, I'd be interested to hear about it. There's the stream function of course, which just records the flux transitions with errors included, with good/bad sectors, but it won't be able to recover a misaligned disk completely.

Cheers!
Imqqmi
 
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