What am I doing wrong ? Disk Media Test
Hi Jim ..
hope you can cure my stupidity on this one.
I recently aquired a large box of 'used' 720k floppies as used previously on Amiga computers.
Obviously I dont want to just use them before I've weeded out any damaged or unuseable disks.
Then I remembered seeing a Disk Media Test button in the utils section of SCP software.
Thats what I need I thought.
I've never used this before but appeared to be a good time to try it.
The floppies as I said are used but blank.
I tried at least 20 expecting some sort of write test ...then a read to confirm which are good.
Drive one selected which is the 3.5" unit in my 2 drive unit (drive 0 being a 5.25" )
But nothing runs ..the floppies dont spin up ..nothing happens at all ..just a fail message every time ?
The computer I'm using runs windows 7.
..and I have made many images previously of commercial Amiga game floppies in .scp ..so I know the unit/drive works ok.
What am I doing or _not_ doing that I should be.
kind regards
Evan aka VS
No doubt it is my stupidity for not understanding.
There is nothing magic about the media test.  Just follow the on-screen instructions like you would when imaging/copying disks.  Have you been using this exact drive in the past to make copies or images?  These dual platform drives are tricky to get working correctly sometimes.  Have you tried making an image of any disk to make sure the whole system is working still?
I suspect many of the disks I aquired must be bad ..so most fail the test Jim..
after dispairing for a while I managed to find one that passed the test.
I guess I will have to do a lot more searching before I find another.
The nature of used disks I guess ...but what other options are there.
many thanks
I find that maybe 5% of all of my blank 3.5” disks will pass all 80 tracks. Typically they start failing around track 73 and fail up to 79.
If I may press your expertise a little further Jim ?
I have processed around 300+ DS DD floppies so far in an attempt to salvage a few for my A1200.
Around 10% passed first time the media test so these were marked as good and thus possibly reliable.
A large number were useless and will be kept only for shutters ..and cases etc
There were however a good few which were borderline with only a few bad tracks reported.
These were kept in a seperate pile..and I was ready to give up on them.
...until that is I erased them first ..and then ran the test again..chosing re-try or ignore when a bad track was found.
Strangely on completion the test was run again..and quite often completed with no errors ?
Now I'm confused ..was the original test flawed in some way ?
Is it possible the constant spinning and surface contact of the heads on the media has somehow fixed the errors ?
Another thought springs to mind ..
could this mild abrasive action have actually 'cleaned' the floppy surface thus restoring it (effectively polishing the disk surface)?
..and finally would disks 'recovered in this way be considered reliable going forward ?
I have left some of these disks overnight and tested again after 'resting' them ..and sure enough they still pass with flying colours.
The ones I have written off usually failed at the start of the test ..errors reported test failed at track zero side 0 or side 1.
Your thoughts on this would be most welcome and possibly enlightning.
Now it gets even more curious..
I took a sample of 5 floppies which reported track errors during the test in excess of single track errors..
these ranged from 2 to 5 errors per floppy and performed the same process as above on each ..
some floppies required 2 passes.
All five now read as good and passed the test just fine ...twice..
These were left overnight and tested again this morning ..
All 5 passed with all 80 tracks reporting 'good'.
I will put these aside and test them again in a few days.
This action does at least apppear to restore floppies which on visual inspection through the shutter door show no physical defects or scratches to the magnetic surface.
what is going on ??
Perhaps in some way the action of writing flux patterns to the disk surface changes the magnetic properties and creates a fix/restore situation...if that's even possible ?
A sort of localised 'degausse'
Only time will tell.
Are you cleaning the heads before every time you do the media test?  You need to!  I am guessing the heads are very dirty.
(03-04-2020, 02:08 AM)admin Wrote: Are you cleaning the heads before every time you do the media test?  You need to!  I am guessing the heads are very dirty.
Indeed I do Jim ..
More likely crap on the disk surface than the heads themselves...and the constant revolutions with heads in contact are cleaning the disks themselves.
not a desireable approach but has got me another 10 useable disks.
Yeah, it could be your disks were subjected to moisture and there is layer of mold or fungus on the surface.  It seems that 3.5” disks were much more susceptible to this than 5.25” disks.  You could try cleaning the disks.  There are some part on Thingiverse that you can 3D print to make it easy to clean 3.5” disks.
Vipersan, be sure to sanity test formatting these disks on a real computer.

Also, try the SCP 1.91 software, I have found the media tests to be problematic and randomly fail on perfectly good disks using the later versions.

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