Disks do not only die of bit-rot...Read this!

[andreas]

Indeed, as I'm now devoid of a load of disks...

SPS project writes a lot of stuff that disks die of bit-rot, that is, data on the magnetic surface loses its integrity.
This is CORRECT, but only half the truth.

You know that situation? No WB handy atm, let alone a copy-prog on the Amiga, so what could you do to test whether your DD disk is still OK? Yes, reformat it on the PC with 720K option.

Then a very odd behavior occurred. Disk surface was CLEAN, no dirt, no dust, I swear. But yet ... errors, errors, errors.

I OPENED the disk.

You guess what happened? Disk surface WAS absolutely clean, but the circular plate was not fastened anymore on the magnetic surface -- it was LOOSE and just FELL OUT!
The glue used for fastening the plate on the surface ring is the cheapest you can find with most disk brands...high-end brands like FUJI did not have this problem.

Sometimes, you may encounter this, if you use a pencil to rotate the disk manually with the disk sitting in your hands, and the surface is calm like still lifes. Yup ... what you have is a wheelspin situation: the position is STATIC, the magnetic surface will not rotate an inch, but the plate will rotate alone!
So when reading an old original disk, even checking the surface to be clean, THAT might be the reason why the disk doesn't work!

I wager that many shrink-wrapped, sealed boxes you buy on ebay for high prices were partly exposed to massive heat and the glue is almost gone, so they're on a silky string!

[BippyM]

Would it be possible to re-glue the metal plate back on carefully? even if it is only temporary to recover the data

[woody57]

Perhaps without risking solvents on the surface the use of the correct thickness of industrial DOUBLE SIDED TAPE would be a safer solution....after all most magnetic media used to be tape spliced in the old days { with digital who needs it ? }

Opinions please

[NOB]

I have opened many disks and cleaned them.(PIC1)
and it works great!
If the disk´s are looking like the second picture all hope is lost!

I have glued 3 or 4 disk´s and the best result was at least 4 broken track´s.
But it work´s.

[NOB]

@Andreas
Yep, the loose circular plate is a no-name disk problem.
Indeed high end brands did not have it.

[Rick Dangerous]

I'm using several HD-Disks on my A500 and A2000.
I remember I tried first to format a blank HDD on the Amiga.
But the format failed at first.
Then I read a thing about the hidden /SELECT option in the MS-DOS command FORMAT. On the following site there you can find a description of this option:
http://www.mdgx.com/secrets.htm#FDISK-S

After I formatted a HD-Disk on the PC with this option, the Amiga was able to format the disk as a normal DD.
It did not work with any brands.

Cheers,
Rick

[Magno Boots]

Oh dear,
Picture two looks like one of those 'Stag' disks I used to own.
If salt can corrode you car, then imagine what it can do to your disks!

[andreas]

Originally Posted by bippym

Would it be possible to re-glue the metal plate back on carefully? even if it is only temporary to recover the data

If you're professional, maybe.

But I would not dare do this, as if some glue gets BEYOND that plate, all may be lost. NOB seems to have good experience with this, so if I encounter this again, I'll snail-mail the disk to him.

[NOB]

Originally Posted by andreas

...as if some glue gets BEYOND that plate, all may be lost.

And the second problem is to center the magnetic surface 100% on the
plate.If it is not centered correctly an unbalannce is the consequence.Followed by tons of read errors.

[NOB]

Originally Posted by Magno Boots

Oh dear,
Picture two looks like one of those 'Stag' disks I used to own.

This is a typically:"I store some disks 20 year´s in a cellar" disk.
BTW:Pic2 shows the original ( ) http://hol.abime.net/2761 disk.

[andreas]

NOB have you ever been able to clean the magnetic surface after you had attempted to blow some dust off the surface and accidentally managed to spit onto the disc? (Yes, SPS also warns to NOT do this, but well, it's hardly purpose is it? I HATE when this happens.)
I had this problem and had to throw away some of my disks because of that, as the surface didn't completely absorb the "fluid".

[dlfrsilver]

Spitting on the disk ahahaaha this also happened to me loool

[fiath]

Originally Posted by andreas

This is CORRECT, but only half the truth.

LOL. I think it is slightly more than half. :P

But its a good point. We should add that other problems like this occur too.

[andreas]

Sorry fiath, "half the truth" was just a sort of abbreviation ... no good choice, I must say, but shorter than needing one sentence alone

[NOB]

Originally Posted by andreas

spit onto the disc?

Take a cup of water with a drop of washing up liquid
and kitchenpaper(Zewa) clean the disk with the wet paper.
Then dry the disk with another piece of paper.
Wait one day.And most disks looking like new disks.(pic1
)
Take care that the circular plate won´t get so wet.
Because of the glue.

[andreas]

KITCHEN TOWELS?
Now you're telling me!

I *did* work with Zewa, and this stuff is porous as HELL!
I can't imagine that you do not get any scratches on the surface by using that! It's mandatory that the paper is soaked thoroughly in the suspension otherwise big "surprises" may be waiting for you ...! Very risky ...

[NOB]

OOPs you are right,my kitchen towel is SOLO Saugwunder not Zewa.
No scratches at all.And maybe wet is the wrong word, clammy/wettisch is more exactly.

[edit]Risky? not really.Inserting a polluted disk is risky -> nasty scratches
are the result.

But, as mentioned above the success depends on the disk quality, too.
(no-name , Fuji...)

[Overdoc]

I always use one of these 'Micro-Faser' ( that's the German name - don't know how they are called in English) towels. I have a very fine one of these, and it cleans away all dirt without leavin behind any scratches

[andreas]

microfibre / microfibre cloth