5.25 floppy drive writing issues

wbahnassi

New Member
Jan 5, 2020
2
0
1
Hi, I have a TEAC FD-55GFR 5.25" 1.2MB disk drive. It reads disks great (both DD and HD) under DOS 6.22. But if I use it to write even one byte on the disk, then the disk gets corrupted. Reading the disk results in "General read error". Trying to format it fails with "Invalid media or track 0 bad - disk unusable". Not even VGACopy can deal with the disk anymore. IMGDisk fails to write with error "NoAdrMark".

I've read that those TEAC drives are known to be some of the best, so I feel bad about throwing this one away if it can be fixed.

Problem is, what part of the disk machinery could result in such fails? A faulty write head?

Things I've tried:
* Reads disks perfectly of all formats
* IMGDISK alignment test succeeds 100%
* Cleaned heads and sensors (index & write protect)
* Connected another floppy drive, reads & writes perfectly, so it's not the controller or the motherboard

Procedure to fail:
* Insert a working disk in drive A:
* Do "dir", files are listed successfully
* Go to drive A: and write something, I use "Echo hi >> test.txt"
* Do "dir", files are listed correctly and new file shows up
* Do "type test.txt", it prints "hi"
* Do "dir", you get "General Read Error" from now and forever

So interestingly, the write seems to succeed at first but the disk gets corrupted a few seconds after writing is done.

Any idea on where to look for the problem?

Best
 

cml37

Moderator
Staff member
May 19, 2019
181
41
28
Washington, D.C. Area
Hi, I have a TEAC FD-55GFR 5.25" 1.2MB disk drive. It reads disks great (both DD and HD) under DOS 6.22. But if I use it to write even one byte on the disk, then the disk gets corrupted. Reading the disk results in "General read error". Trying to format it fails with "Invalid media or track 0 bad - disk unusable". Not even VGACopy can deal with the disk anymore. IMGDisk fails to write with error "NoAdrMark".

I've read that those TEAC drives are known to be some of the best, so I feel bad about throwing this one away if it can be fixed.

Problem is, what part of the disk machinery could result in such fails? A faulty write head?

Things I've tried:
* Reads disks perfectly of all formats
* IMGDISK alignment test succeeds 100%
* Cleaned heads and sensors (index & write protect)
* Connected another floppy drive, reads & writes perfectly, so it's not the controller or the motherboard

Procedure to fail:
* Insert a working disk in drive A:
* Do "dir", files are listed successfully
* Go to drive A: and write something, I use "Echo hi >> test.txt"
* Do "dir", files are listed correctly and new file shows up
* Do "type test.txt", it prints "hi"
* Do "dir", you get "General Read Error" from now and forever

So interestingly, the write seems to succeed at first but the disk gets corrupted a few seconds after writing is done.

Any idea on where to look for the problem?

Best
Could it be a disk controller issue? Have you tried the drive in another system?
 

wbahnassi

New Member
Jan 5, 2020
2
0
1
I haven't tried it on another machine. Unfortunately I have only one floppy-capable PC. However, I have another 3.5" 1.44MB drive. If I connect the 3.5" floppy drive instead of the 5.25" then the 3.5" drive is able to read and write successfully without trouble.
I don't think this completely rules out the disk controller but it's an indicator that it's probably not the disk controller. Of course I make sure that the BIOS is configured correctly for each case (5.25" 1.2MB vs 3.5" 1.44MB).

In the mean time I'm gonna have to find someone in my area who has a floppy-capable PC so I can try the drive on his computer instead of mine. I'm in Montreal Canada, so if anyone is close by let me know 😊

So yeah, any suggestions are still welcome.
 

Grumgi

New Member
Jan 23, 2020
6
0
1
I'm not quite sure what could be wrong with the thing, honestly; my knowledge of 80's computing is pretty terrible. However, with that accounted for, there are a few suggestions even I can muster.

Find the documentation for the drive itself and make sure all the voltages are right, and that all the connections are correct too. a faulty ground line or some other electrical mishap could probably fry the disk while writing to it. It's also possible that there's something messing up the connection to the controller as well, but I'm not completely sure.
Might also wanna try reinstalling DOS 6.22, sometimes a bad install can screw up arbitrary things and be nigh undetectable.

That's all I can think of. As I said before, I know next to nothing about 80's computing, my knowledge base begins with the deprecation of 5.25 drives/floppies onward. I hope this helps in some way.