Can you read the disks on a different computer ? Those disks must be formatted as 360k type and not 1.2Mb, if you created the disks on a computer with a 1.2MB floppy drive they generally will not work when reading from a 360k floppy drive.

Unfortunately I don't have access to another computer with a 5.25 drive. They are the original 360K boot disks that came with the machine though, so they should read just fine. I get the same results with either drive I use.

Particularly old diskettes like to fail in strange ways.

What was said about the 360K/1.2M drives not being very interchangeable is very true.

Have you cleaned the heads? Do the stepper and hub rotate freely? Is the lock lever lubricated and does it engage all the way smoothly?
If your drive has an index sensor you should probably clean it as well.

EDIT: If it wasn't obvious please make sure the cables are plugged in the right way and your jumpers on the drive are set correctly

Do you have another machine you could try plugging the drives in to? Ideally one that can boot from a hard drive so you can run tests without having to boot from a floppy. I'm assuming that the pinouts are compatible with standard PCs (this: http://www.retroisle.com/amstrad/pcs/techdetail.php suggests they are).

FAMICOMASTER wrote on 2021-06-06, 19:34:

Particularly old diskettes like to fail in strange ways. […]
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Particularly old diskettes like to fail in strange ways.

What was said about the 360K/1.2M drives not being very interchangeable is very true.

Have you cleaned the heads? Do the stepper and hub rotate freely? Is the lock lever lubricated and does it engage all the way smoothly?
If your drive has an index sensor you should probably clean it as well.

EDIT: If it wasn't obvious please make sure the cables are plugged in the right way and your jumpers on the drive are set correctly

I've given the heads a clean, the motors rotate freely (the one drive uses a worm shaft and is a bit stiff by comparison to the other drive, but not such that the head assembly doesn't move by itself when the machine is powered on), and the lock levers on both drives engage properly. I haven't had a look at the index sensor yet, I'll give that a go.

EDIT: Cleaned the index sensor, no difference. I also double checked that the jumpers are set correctly.

snufkin wrote on 2021-06-06, 19:48:

Do you have another machine you could try plugging the drives in to? Ideally one that can boot from a hard drive so you can run tests without having to boot from a floppy. I'm assuming that the pinouts are compatible with standard PCs (this: http://www.retroisle.com/amstrad/pcs/techdetail.php suggests they are).

That's my next port of call. I don't have a cable on hand that I can use for my other machines (the one in the Amstrad is attached to the motherboard and doesn't come off) so I've had to buy one off of eBay. Once that arrives I'll test the drive in my W98 machine and see how that goes.

Hmm. The heads are in contact with the media, right? Heads should be spring loaded and gently hold the media between them.

Do you have any other machines with a diskette drive at all? Or any other diskettes to test with.

In the early 90s I had a PC1640 and the original disks that came with it were toast, don't know if they'd had hard use or bad storage. Found an Amstrad specialist that still had NOS disks, bought those (In the 90s) copied them to good quality blanks, and put the read once disks away... never had to go back to them and the Amstrad stuff got disposed of late 90s. So just saying really that used originals were already flaking out in the 90s.

Can you not fit a 3.25" 720k floppy drive ,or a 1.4meg fdd acting as a 720kb drive, in the system in the system and use something like these stiffys?:

They'll take a 720k drive, but they don't have a twisted cable, so you have to set the jumpers/switches on the drives right. Also I think you need the edge connector to 34pin adapter. Used to come with a cheapie cheap 5.25 drivebay adapter kit in the day along with a 5.25/3.5 power adapter, not sure you can still get those... hmm, some ten dollar ones on evilbay.

FAMICOMASTER wrote on 2021-06-06, 22:10:

Hmm. The heads are in contact with the media, right? Heads should be spring loaded and gently hold the media between them.

Do you have any other machines with a diskette drive at all? Or any other diskettes to test with.

They seem to be be yes. I'm starting to think it may be the disks themselves. Amstrad were known for cheaping out, so it wouldn't be out of the question that they used cheapo disks that degrade quickly. They do look rather nice with their multi-coloured shells though

BitWrangler wrote on 2021-06-07, 00:19:

In the early 90s I had a PC1640 and the original disks that came with it were toast, don't know if they'd had hard use or bad storage. Found an Amstrad specialist that still had NOS disks, bought those (In the 90s) copied them to good quality blanks, and put the read once disks away... never had to go back to them and the Amstrad stuff got disposed of late 90s. So just saying really that used originals were already flaking out in the 90s.

Doesn't suprise me with Amstrad and their cost cutting. I have a set of new sealed 3M 360K floppies sitting here, so once the cable arrives (assuming my theory is correct and the drives work) I will just create a new set of boot disks from the archive here: http://www.freetimeweb.nl/home/computer/alt/l … awson/files.htm

Caluser2000 wrote on 2021-06-07, 00:28:

Can you not fit a 3.25" 720k floppy drive ,or a 1.4meg fdd acting as a 720kb drive, in the system in the system and use something like these stiffys?:

I don't have an adapter on hand to be able to use the floppy drives I have with the cable in the machine, nor a compatible addon card that I could use

Just an update. I borrowed a set of confirmed working MS-DOS 4.01 disks from a friend and they didn't work either. So I guess it must either be the drives or the floppy controller.

EDIT: Final update, both drives are confirmed working by testing them in my Windows 98 machine. The system boot disk read just fine. The machine, either the cable or the floppy controller, is at fault.