My LS-120 acts up like that if the power connector doesn't have a good fitting. Moving the power cable a little sometimes resolves the issue.

I don't have any 120MB disks, so my experience is with 1.44MB disks exclusively.

fosterwj03 wrote on 2021-01-13, 21:09:

My LS-120 acts up like that if the power connector doesn't have a good fitting. Moving the power cable a little sometimes resolves the issue.

I don't have any 120MB disks, so my experience is with 1.44MB disks exclusively.

Thank you for your suggestion! 😀 I just tried moving the cable it but it doesn't help. 🙁
Since the drive only uses +5V, has been plugged and unplugged 10+ times during testing and handles 120MB SuperDisks fine I don't think the issue is related to flaky contacts on the power input.

I think potentially the floppy drive 1.44mb uses a different set of heads on the LS-120, perhaps those are out of alignment or broken/dirty? In my experience, only the LKM-F934 and later are particularly good (and they fail in their own ways), but the previous versions are slow and quite prone to failure

Thermalwrong wrote on 2021-01-14, 01:42:

I think potentially the floppy drive 1.44mb uses a different set of heads on the LS-120, perhaps those are out of alignment or broken/dirty? In my experience, only the LKM-F934 and later are particularly good (and they fail in their own ways), but the previous versions are slow and quite prone to failure

Agree ! From memory the heads on LS-120 are very small compared to floppy heads. I remember this Warning: Do not clean them with a floppy disk cleaner disk or it can ruin the heads. May that was already done and why it has issues with floppies.
One thing: the tracks on LS-120 disks are very small compared to standard floppy tracks. Have you tried reading a floppy recently written off a known good 1.44Mb floppy drive ?
You could be facing the problems of the 360k vs 1.2mb floppy disk/drive read/write issue with track size issues, just a guess. I never kept a LS-120 drive as the Zip drives were much better IMHO

Thermalwrong wrote on 2021-01-14, 01:42:

I think potentially the floppy drive 1.44mb uses a different set of heads on the LS-120, perhaps those are out of alignment or broken/dirty? In my experience, only the LKM-F934 and later are particularly good (and they fail in their own ways), but the previous versions are slow and quite prone to failure

Horun wrote on 2021-01-14, 02:30:

Agree ! From memory the heads on LS-120 are very small compared to floppy heads. I remember this Warning: Do not clean them with a floppy disk cleaner disk or it can ruin the heads. May that was already done and why it has issues with floppies.
One thing: the tracks on LS-120 disks are very small compared to standard floppy tracks. Have you tried reading a floppy recently written off a known good 1.44Mb floppy drive ?
You could be facing the problems of the 360k vs 1.2mb floppy disk/drive read/write issue with track size issues, just a guess. I never kept a LS-120 drive as the Zip drives were much better IMHO

Hey guys, thank you for the ideas! 😀 I'm trying to answer them one by one:

As far as I can tell the drive has two heads, one on the upper side of the disk, one for the lower side - just like a regular 1.44M floppy drive - but possibly with multiple gaps (that's the term I found here, there's also a high res pic of the head assembly on that page. direct link)
Since at least mechanically the head assembly seems to be one part and the drive reads/writes LS-120 disks fine I'm doubtful of a misalignment issue. As stated before the drive will also often start copying a file or two before it craps itself. If a file is copied the copy is usually intact which would also make an alignment issue less likely in my (admittedly uneducated!) opinion.

However if the read/write heads contain different gaps for either disk format one gap may be dirty while the other isn't. The heads look pretty clean though. A defect on one part of the head is also not impossible though again usually the drive will start copying files in either direction initially (and often create one or two working files!) but then just stops and blinks.
This is why I'm inclined to think the drive is actually operational and the issue is related to user error rather than a failed drive. (Though possibly that's just wishful thinking!😅)

Thank you, Horun, for pointing out the dangers of using regular cleaning floppies with this drive! I had read another thread here pointing out the dangers so I was aware but if I wasn't I would have killed my drive for sure so thank you for mentioning this!
Does anyone have an idea of how to clean the heads without risking damage while not having access to the official cleaning disk?

I didn't mention this before but I have tried freshly formatted 1.44M floppies in this drive as well as formatting floppies with the drive. The drive initially reads all known good floppies (reads directory listing and copies 0-2 files on freshly formatted and/or written to disks as well as factory driver disks) but it fails within a few seconds when trying to format a floppy disk.

By the way I'm not that interested in using the drive for reading/writing LS-120 disks, I'd much rather get it working to read/write regular floppies at double the speed. Also apparently those drives are much better at reading failing floppies than regular FDDs.

I am completely inexperienced with LS-120 drives. Are there any special BIOS settings I have to make? Please point out completely obvious stuff as well since again I'm a n00b with those drives.
Also I just noticed the IDE activity light is solid on when the drive crashes the PC. If I use the reset button instead of powering down the computer after it locks up the drive is not recognised in BIOS upon next reboot.

I just tried using the LS-120 drive to write a single ~1MB file to a floppy disk I previously formatted in a regular FDD.
The file is written successfully and can be read using the FDD as well the LS-120 drive.
I then tried writing the same file using the FDD and reading it on the LS-120 drive. This works too.
Trying to format a floppy disk in the LS-120 drive still crashes the PC every time.
Next I tried writing three small text files to a floppy using the LS-120 drive.
All successful.
Tried deleting them again. All good.
Then I tried eight small text files.
Write successful. For a second it hangs when deleting them but catches itself and finishes.
Next I tried copying the eight text files plus the ~1MB file to the floppy using the LS-120 drive.
Works. Deleting them also works.
Writing, reading and deleting a single ~1.25MB file also works fine.
Trying to format a floppy disk in the LS-120 drive still keeps crashing the PC every time.

I can not makes any sense of this but at this point I am almost certain I have misconfigured something. Can somebody help me out?

Edit: Got cocky and tried a Thorough check using ScanDisk. It went well at first, struggled a bit but managed to go on but finally crashed the PC at unit 1765 of 2847. The drive stops reading and just blinks.

This might sound like an odd suggestion, but have you tried to format a disk in real-mode DOS (i.e. prior to Win98 boot-up into GUI)? I wonder if you have a controller/interface/driver issue within Windows. Your motherboard's BIOS will likely treat the LS-120 drive as drive A: (or B: if you have an ordinary floppy drive, too).

This will only work with 1.44MB floppies unless you load the DOS LS-120 and ATAPI drivers (I suggest not loading those drivers for the test).

Just a thought.

fosterwj03 wrote on 2021-01-14, 15:35:

This might sound like an odd suggestion, but have you tried to format a disk in real-mode DOS (i.e. prior to Win98 boot-up into GUI)? I wonder if you have a controller/interface/driver issue within Windows. Your motherboard's BIOS will likely treat the LS-120 drive as drive A: (or B: if you have an ordinary floppy drive, too).

This will only work with 1.44MB floppies unless you load the DOS LS-120 and ATAPI drivers (I suggest not loading those drivers for the test).

Just a thought.

You may be up to something here. The drive is more reliable less unreliable in pure DOS (6.22). Roughly two of three formats work, copying a whole disk from FDD A: to LS-120 B: works about every second time but a surface scan has yet to be completed. Most importantly when it fails it doesn't lock up or crash the PC most of the time.

Also in DOS 6.22 I noticed for the first time the drive will often think the disk had been removed when it fails. It will only read the disk again after removing and reinserting it. Only issuing a new read command like with a regular FDD does nothing. Maybe some switch is failing on the drive?

In Win98SE DOS mode the drive would sometimes stop reading and then assume the disk was 120MB instead of 1.44MB. This might also indicate some sort of failing switch or disk sensor I assume.

This is all very weird to me. 😅