Floppy Disks: Testing, Recovering, Reusing and Recycling

[demolition]

Originally Posted by djukon

How do you mark bad sectors on a floppy to avoid using those sectors (PC and Amiga)?
If you find a floppy with a few failing sectors, should you keep using them even if the rest is good, or throw them out?
When floppy drives are no longer easily accessible (possibly in a decade or so), how can the floppy drive heads be properly aligned? I've read it is expensive. Are the machines that do this coming down in price (as they are obsolete)? What are they called (keywords) and how big are they? Something you can store in a garage?

On the Amiga, you don't mark bad sectors, which is why I throw away DD disks if they have even one bad sector.
For head alignment you need a calibration floppy and a way to measure the signal from the heads, for example an oscilloscope. What you want to achieve is the best SNR (usually highest amplitude) when reading from the calibration floppy.

[Jope]

On the Amiga you can use MyFormat which allocates the bad sectors for you. The Amiga filesystems don't have the same kind of bad sector marking feature as the MS FAT does.

[djukon]

Originally Posted by prowler

I used a pair of MS-DOS command line utilities for setting and clearing bad sector markings on floppy disks in days gone by.

I'll see if I can find them again if you're interested in trying them out.

If it is easy for you to find, great, I'd really appreciate it. Thanks, prowler.

I can add that "format a: /t:80 /n:9" on Windows for DD floppies marks badblocks in the FAT12 filesystem. I recently put many of my DD floppies through a FAT12 windows reformat process, followed by SpinRite, and the consequence was that one or two additional badblocks were discovered in the floppies that already had some badblocks identified by windows' format. SpinRite also inverts data for testing. I also suspect the magnetization properties on those floppies is failing and that is why format didn't pickup all bad sectors.

Originally Posted by demolition

On the Amiga, you don't mark bad sectors, which is why I throw away DD disks if they have even one bad sector.

I suspected that much. Thanks for chiming in, demolition.

Originally Posted by Jope

On the Amiga you can use MyFormat which allocates the bad sectors for you. The Amiga filesystems don't have the same kind of bad sector marking feature as the MS FAT does.

Thanks for the tip, Jope. So what exactly does the MyFormat tool do? Does it create dummy filler files which "reside" in the bad sectors? Which I guess would avoid real data being written to the occupied bad sectors.

Originally Posted by demolition

For head alignment you need a calibration floppy and a way to measure the signal from the heads, for example an oscilloscope. What you want to achieve is the best SNR (usually highest amplitude) when reading from the calibration floppy.

Now where does one get a calibration floppy? I doubt they are still fabricated.

I suspect my A500+ floppy drive seems to be slightly misaligned, let me know what you think it may be. It even sounds "different" when reading the disks (from what I remember). Continuous regular formatting (reading and writing) seems to sound the same, it is when the heads go back and forth like crazy that it seems to sound like it is in slight "pain", not a healthy grind. In fact it always sounded like this since I purchased the A500+ second hand in 2008. Some floppies work well, other don't (and many are perfectly fine formatted on the PC). With X-Copy format and check, the results are variable. I have cleaned the drive heads with a floppy disk cleaner and the accompanying liquid.

I still have the original A500+ drive I had, which I have the sneaking suspicion is in better condition. I'll test it in a few weeks/months. I'd like to learn more about floppy head drive alignment, can anyone point me to a good in-depth guide on the topic (if it exists)?

Thank you all for your responses.

[demolition]

Originally Posted by djukon

Now where does one get a calibration floppy? I doubt they are still fabricated.

I suspect my A500+ floppy drive seems to be slightly misaligned, let me know what you think it may be.

I don't know where to get a reference disk either. You could probably write one yourself if you have a drive that you know to be 100% correctly aligned, but who has that?

Do not mess with the alignment until you are 100% sure that is your problem. Most drives should never need readjustment unless it was physically damaged / dropped, and in that case a realignment might not fix the drive completely.

My 500+ had problems with its drive as well. It would read fine, but writing/formatting produced various errors. It turned out a capacitor was leaking on the floppy drive PCB, so if your 500+ also has a Panasonic drive like mine, I would check it out. The capacitor in question was located right below the eject button, and on my drive, the IC next to it was all green and furry. Replacing the capacitors (did the other one on the back of the drive as well although it was not leaking yet) got rid of the problem.
The Panasonic drive in my A1200 also had leaking caps, although on this one it had not developed writing problems yet (probably would not take long until it did).

The Chinon drives you normally see in 500s do not have any of these aluminium electrolyte caps which go bad after 10-15 years.

[djukon]

Originally Posted by demolition

Do not mess with the alignment until you are 100% sure that is your problem.

Rest assured, I wasn't thinking about it.

Originally Posted by demolition

My 500+ had problems with its drive as well. [...] so if your 500+ also has a Panasonic drive like mine, I would check it out.

I completely forgot to check the drives' caps. I have a TEAC FD-235F drive from my original A500+, the other one, I don't know what brand and model it is, I would have to open the A500+ up to check. Sidenote: I'll do it ASAP, it is just my that wife should be having a baby in the next couple of days, so this is not the best time for hardware tinkering. The TEAC drive has 4 caps on the bottom and there are a few dark brown (rust?) particles around the solder points for the cap near the eject button. Not like the bit of battery leakage I got on the 500+ some years ago (fixed).

Originally Posted by demolition

The Chinon drives you normally see in 500s do not have any of these aluminium electrolyte caps which go bad after 10-15 years.

Roger that, I'll keep an eye on them for spares.

Thanks again, demolition, for your contribution.

[Solo761]

I have one TEAC and one Panasonic that stopped reading floppies. I changed capacitor(s) on both of them but it didn't help. Then I tried TrackDiskSync from aminet, used one floppy that reads disks to make it's calibration floppy and then tried to play it in these two "defective" ones. Sound was off, both "by ear" and by microphone (I used frequency analyzer app on my cell phone). They were simply different frequency when compared to working floppies. I it by rotating head motor a bit until frequency matched those of working drives but it still didn't help. They still won't read floppies that are readable by others.

I've also searched for how would one calibrate floppies with oscilloscope but haven't found anything.

[djukon]

Originally Posted by Solo761

I changed capacitor(s) on both of them but it didn't help. Then I tried TrackDiskSync from aminet[...]

Thanks for the input, Solo761, this gives me a broader perspective on this topic.

[demolition]

Originally Posted by djukon

Roger that, I'll keep an eye on them for spares.

I do think that the Panasonic drives seem very mechanically solid which is why I want to fix and keep them and not just replace them. The little job of replacing the caps is worth getting a quality drive in return. Just remember that you might need to replace the caps again in ~10 years. :-)

[Solo761]

TEAC I messed up myself . It was from A1200 I got. It worked fine for about a month then it stopped reading. I googled what could be the problem and found a bit info on drive calibration and alignment. Unfortunately none of that info had any precise instruction so I loosened screws on the head and moved it a bit back and front. Unsuccessfully. After that I found that capacitors could be the issue. Replaced it and tried again, and was unsuccessful again. I think that it might be because I moved the head (upper part). Maybe I even got it aligned, but lower part of the head looks on different track so it doesn't work. I don't know which head TrackDiskSync tool uses for it's measurement.

Panasonic one was from A500, it was almost mint condition, clean and white. Again it worked for few days and then it stopped reading. I change only the capacitor on that one but it didn't help. I only tried reading TrackDiskSync calibration floppy with it, haven't messed with internals.

In the end I left A500 with that faulty panasonic, that's my backup A500 so it doesn't matter at the moment, if I find some instructions how to align/calbirate floppy drive I'll give it a go, but I won't experiment with it.
For A1200 I modded Samsung SFD-321B drive so it reads Amiga floppies. Luckily metalic part that holds eject button is almost the same size as in TEAC floppy. It's only 1 millimeter wider. I took 0.5 mm from each side with dremel and original eject button from TEAC fits like a glove. I would even say this moded one works better than original floppy (well, it's way newer than original one so...)

Panasonic has different eject button and so far I haven't found anything similar. I guess I'll have to get one PC Panasonic floppy and mod it to replace one in A500.

[demolition]

When a floppy drive works for a short while and then stops reading, puts my suspicion on a dirty head. If you have used a moldy disk in the drive, it would stop reading after a little while as the mold builds up on the head. And if you have two drives with similar behavior it points even more in that direction.
Luckily it is easy to clean the heads to check if this is the case.

[Solo761]

I tried cleaning the head with alcohol and qtips, but it didn't help. Floppies I used were new HD (with HD hole plugged) so I doubt it's mold related. And none of the other Amigas were affected (few A500 and A600). I even used A600 cca two months ago to scan floppies with x-copy and check for bad sectors, that's about 200+ floppies. And it still works fine. These floppies weren't in a basement. I store them in plastic boxes with bunch of silica gel packs in every box .

[mr.vince]

For the record: alignment disks are analogue; you can not make copies or write them with a standard drive. You need a "drive" with servos instead of steppers so you can write alignment figures.

[Jope]

Originally Posted by djukon

Thanks for the tip, Jope. So what exactly does the MyFormat tool do? Does it create dummy filler files which "reside" in the bad sectors? Which I guess would avoid real data being written to the occupied bad sectors.

As far as I remember, it just marks the sectors as used in the disk bitmap, it doesn't create actual files.

[Supamax]

(Regarding MyFormat)

Originally Posted by Jope

As far as I remember, it just marks the sectors as used in the disk bitmap, it doesn't create actual files.

Interesting. Where can it be found/downloaded?

[Jope]

As always, Aminet would be the first place to look. :-)

[demolition]

I guess if you ran some kind of file system check on the disk, like DiscDoctor, the marked sectors would then be freed?

Also mark the disk somehow so you remember that it has bad sectors, so you don't go ahead and write an ADF to it which might have data in the corrupted area.

[prowler]

Originally Posted by djukon

If it is easy for you to find, great, I'd really appreciate it. Thanks, prowler.

I've uploaded to The Zone for you the original zip archive containing the set of utilities for finding, marking and unmarking bad disk clusters.

Have fun!

[Jope]

Originally Posted by demolition

Also mark the disk somehow so you remember that it has bad sectors, so you don't go ahead and write an ADF to it which might have data in the corrupted area.

I personally never use the error marking feature when I format with myformat.. I just discard the broken disks.

Then again thanks to my scene archival work, I have way too many floppies hanging around.. People don't tend to want them back after they lend them for dumping. :-D

[djukon]

Originally Posted by demolition

I do think that the Panasonic drives seem very mechanically solid which is why I want to fix and keep them and not just replace them. The little job of replacing the caps is worth getting a quality drive in return. Just remember that you might need to replace the caps again in ~10 years. :-)

Thanks for the insight, demolition .

Originally Posted by Solo761

[TEAC/Panasonic Drives]

Thanks for the shared experience, Solo761 .

Originally Posted by Solo761

I store them in plastic boxes with bunch of silica gel packs in every box .

How many silica gel packs are enough? I have one or two per plastic case (the 40/80 kind).

Originally Posted by mr.vince

For the record: alignment disks are analogue; you can not make copies or write them with a standard drive. You need a "drive" with servos instead of steppers so you can write alignment figures.

Thanks for chiming in, mr.vince, with this precious information .

Originally Posted by Jope

As far as I remember, it just marks the sectors as used in the disk bitmap, it doesn't create actual files.

Originally Posted by demolition

I guess if you ran some kind of file system check on the disk, like DiscDoctor, the marked sectors would then be freed?

Most likely the case, good point, demolition.

Originally Posted by demolition

Also mark the disk somehow so you remember that it has bad sectors, so you don't go ahead and write an ADF to it which might have data in the corrupted area.

Does anyone have a short note tagging system in place for this? Here are some examples I use on the lack of a standard:

• "100% OK XC 14.05" - Disk completely OK, checked with X-Copy in May of 2014;
• "4BS SR 14.05" - 4 Bad Sectors, checked with SpinRite in May of 2014.

Originally Posted by prowler

I've uploaded to The Zone for you the original zip archive containing the set of utilities for finding, marking and unmarking bad disk clusters.

Have fun!

Thanks, prowler, got it!

Originally Posted by Jope

I personally never use the error marking feature when I format with myformat.. I just discard the broken disks.

Don't forget that Nick Gentry is accepting discarded floppies as artistic canvas.

Originally Posted by Jope

Then again thanks to my scene archival work, I have way too many floppies hanging around.. People don't tend to want them back after they lend them for dumping. :-D

Keep them safe .

[Solo761]

Originally Posted by djukon

How many silica gel packs are enough? I have one or two per plastic case (the 40/80 kind).

I use 10-15 packs per box. But these are not original boxes, I had bunch of floppies and got few plastic boxes for freezer cca the size of a floppy. They're reasonably watertight and can take about 100 floppies.
I'm not sure how much is enough, but I got 50 of them for $1 on ebay so i threw them in generously .