Repairing bad floppy disks

[kallisti5]

So, I can't find this process documented anywhere, so I wanted to post it here.

I have a *big* box of 3.5" bad / crudely magnet wiped floppy disks.
None of them have been functional, and writes always fail.

I've figured out a process to bring these floppy disks back to life.

Note: We are *not* saving data here.. the goal is a blank functional disk.

Tools:

• GreaseWeazel
• Electric handheld degausser / aka "Tape Wiper / eraser"
• A blank floppy disk image (blank-floppy.dsk)

Process:

1. Inspect media for damage / mold / etc. Throw the disk away if it is physically damaged.
2. Put floppy disk into GreaseWeasel
3. Run gw erase --hfreq - Attempt a high frequency format
4. Run gw write --format ibm.1440 blank-floppy.dsk - Write the empty floppy disk image
   1. Success without track errors? Done! You have a perfect floppy.
   2. Failure? "Writing Track (Verify Failure: Retry #1)", etc? Continue.
5. Eject disk, lay the floppy disk on a flat surface label down (away from anything magnetic or metal)
6. Run the degausser over the floppy disk in a circular even motion. It should vibrate when you do. Release button.
7. Flip the disk over. Run the degausser over the floppy disk in a circular even motion. It should vibrate when you do. Do not release button. Continue
8. Slowly move the degausser away from the floppy disk in smooth, even, circular motion until you're around 12 inches away, then move it completely away straight up and turn it off. (this should take around 15-20 seconds total). (Think tornado shape)
9. Run gw erase --hfreq - Attempt a high frequency format
10. Run gw write --format ibm.1440 blank-floppy.dsk - Write the empty floppy disk image
    1. Success without track errors? Done! You have a perfect floppy.
    2. Failure? You can try the degaussing again, or toss the floppy.

So far, I have around an 80% success rate "fixing" bad floppies with this process. The degausser pushes the magnetic poles around on the media, and then the slow movement away (important) leaves them at an even unmagnetized state. I think these disks go bad because they get magnetized over time which prevents the drives from "flipping" the magnetic bits on the media.

Warning: Magnets will not work. They will further magnetize the disk and make things worse. (i've tried) . You need a degausser which rapidly alternates magnetic poles.

I remember my *OLD* electronic engineering professor doing this process to CRT's with a big coil, and he *always* did the slow spiral move away.
This stuff is kind of a lost art, so I wanted to post it somewhere (especially since our supply of good floppy disks is dwindling)

 

[kallisti5]

Here's a before on a random floppy disk:

T78.0: Writing Track (Flux: 200.0ms period, 220.0 ms total, Terminate at index)
T78.1: Writing Track (Flux: 200.0ms period, 220.0 ms total, Terminate at index)
T78.1: Writing Track (Verify Failure: Retry #1)
T78.1: Writing Track (Verify Failure: Retry #2)
T78.1: Writing Track (Verify Failure: Retry #3)
T79.0: Writing Track (Flux: 200.0ms period, 220.0 ms total, Terminate at index)
T79.1: Writing Track (Flux: 200.0ms period, 220.0 ms total, Terminate at index)
T79.1: Writing Track (Verify Failure: Retry #1)
T79.1: Writing Track (Verify Failure: Retry #2)
T79.1: Writing Track (Verify Failure: Retry #3)
** FATAL ERROR:
Failed to verify Track 79.1

(runs through Degaussing process)

Here's the after:

T78.0: Writing Track (Flux: 200.0ms period, 220.0 ms total, Terminate at index)
T78.1: Writing Track (Flux: 200.0ms period, 220.0 ms total, Terminate at index)
T79.0: Writing Track (Flux: 200.0ms period, 220.0 ms total, Terminate at index)
T79.1: Writing Track (Flux: 200.0ms period, 220.0 ms total, Terminate at index)
All tracks verified