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Sinclair PC500SD/Amstrad PC1512 Floppy Drive Issues

G

Gr8Britton

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Joined
May 29, 2024
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38
Bit of a long post but would appreciate any suggestions. I inherited a PC500SD (Single Floppy Disk). When I got it, there were no disks. I later found a person on eBay to send me two 'new' MS-DOS floppies. When I got them, the floppy drive made loud noises like it was trying but it would boot or read the disks. I got a 5.25" drive cleaning kit and ran it a bunch of times. Meanwhile, I received my PicoMem card and have been booting via 'HDD' image and/or FDD image. That all works great. I tried booting via HDD and then using the A: but no disks could ever be read. So, I chalked it up to a bad drive.

I ordered an old Beltran XT PC from someone as it had 2 360k disk drives and the seller said both are working. Cha-ching! I received that a few days ago and last night attempted to swap a drive. However, I had the exact same symptoms with the known good drive. I verified with the seller and he said he was very 'anal' about that and guarantees they worked. So, I put the original drive back in and had the same results as the replacement drive. One time, it seemed like it formatted a blank disk ( and does recognize the disk as a 360k disk when run format) but would get abort, retry fail when trying to read the disk. Every disk I try has the same issue.

While I had it open, I check the drive and it was VERY clean and everything spun nice and free. I'd have to remove a few cover brackets to get to the head to clean but I'm thinking that is not an issue.

1) Any trusted sources you use to get known good disks? (Either DOS or blank)
2) Anything special re: Amstrad PCs that I should consider? I verified the drive is on DS0 and even changed it to 1, just in case. I got a faulty drive error when I did that so I'm confident the disk is seen by the PC but just has trouble reading the disks.

Thanks!
 
It is worth getting your own setup to make disks on a modern PC. Greaseweasel works well. Otherwise you will need a way to transfer files to it anyway - An alternative is to use FlashFloppy (Gotek). Then you can just place images on it.
 
Regarding the floppy disks, I hope you're trying to use DD disks, and not HD ones. HD disks may well give the result you're reporting, the format may appear to work, but the subsequent read may give problems.

Also, if the disks have been used before, you should try to wipe them manually (use a magnet). If they've been used on a 96tpi drive, there may be residual data still there, and again, the format may appear to work, but the read may pick up old data from the edge of the track and give errors.

I have a 1640 boot disk (just this one) with DOS 3.2 on that I would have used when I had a 1640. This may not boot correctly on another machine, but it should at least complete before giving errors, and the errors may well be about hardware and not a disk problem. I have read the disk recently to check which DOS version was on it, and it was reading fine. If I was to make a copy this would be on a 96tpi drive, bit I have some virgin DD disks, and I could test that it was reading OK afterwards. I'm in the UK by the way.

Geoff
 
GeoffB17 said:
Regarding the floppy disks, I hope you're trying to use DD disks, and not HD ones. HD disks may well give the result you're reporting, the format may appear to work, but the subsequent read may give problems.

Also, if the disks have been used before, you should try to wipe them manually (use a magnet). If they've been used on a 96tpi drive, there may be residual data still there, and again, the format may appear to work, but the read may pick up old data from the edge of the track and give errors.

I have a 1640 boot disk (just this one) with DOS 3.2 on that I would have used when I had a 1640. This may not boot correctly on another machine, but it should at least complete before giving errors, and the errors may well be about hardware and not a disk problem. I have read the disk recently to check which DOS version was on it, and it was reading fine. If I was to make a copy this would be on a 96tpi drive, bit I have some virgin DD disks, and I could test that it was reading OK afterwards. I'm in the UK by the way.

Geoff
Click to expand...
Good suggestions. No did not think to check if they were HD, just if 360k. I'll check that tonight.

I don't have a magnet, but I'll see what I can do. Thanks!
 
GeoffB17 said:
Regarding the floppy disks, I hope you're trying to use DD disks, and not HD ones. HD disks may well give the result you're reporting, the format may appear to work, but the subsequent read may give problems.

Also, if the disks have been used before, you should try to wipe them manually (use a magnet). If they've been used on a 96tpi drive, there may be residual data still there, and again, the format may appear to work, but the read may pick up old data from the edge of the track and give errors.

I have a 1640 boot disk (just this one) with DOS 3.2 on that I would have used when I had a 1640. This may not boot correctly on another machine, but it should at least complete before giving errors, and the errors may well be about hardware and not a disk problem. I have read the disk recently to check which DOS version was on it, and it was reading fine. If I was to make a copy this would be on a 96tpi drive, bit I have some virgin DD disks, and I could test that it was reading OK afterwards. I'm in the UK by the way.

Geoff
Click to expand...
The disks do not have any marking to differentiate. However, all of the disks I have are brown-ish in color and have a black hub ring. My research tells me that it they should be DD.

I tried 11 disks and everyone of them failed formatting, stating: "Invalid media or Track 0 Bad - disk unusable"

I tried using a magnet from my fridge (not expecting it to be strong enough but worth a shot) and that made no difference.
 
A magnet won't be enough - You could try attaching a neodyme to a power drill, but what you want is a degaussing wand. They are cheap... You can get good media degaussers too - The radio shack is supposed to be good for that.

Did you clean the drive? I often find old disks shredding is the cause of subsequent failures... You can use Cyclomethanicone to lubricate the disk surface also.
 
Thanks for the extra info.

The specific error message, re track 0, is significant. Disks that say that suggest actual damage, either to the disk, or the drive. I have had cases though where this message has gone after use of the magnet, but this is rare.

A fridge magnet would not be strong enough however.

Regarding DD/HD, yes, DD disks are browner rather than blacker, and HD disks seem less likely to have the hub ring, but the best indicator is to hold the disk up to a bright light and see how translucent the magnetic material is. A DD disk will usually show zero evidence of the light through the disk, while most HD disks will allow a definite hint of the light to show through. The material is chearly much thinner - i.e. the magnetic coating.

Best bet immed is to try to clean the head.

Geoff
 
GeoffB17 said:
Thanks for the extra info.

The specific error message, re track 0, is significant. Disks that say that suggest actual damage, either to the disk, or the drive. I have had cases though where this message has gone after use of the magnet, but this is rare.

A fridge magnet would not be strong enough however.

Regarding DD/HD, yes, DD disks are browner rather than blacker, and HD disks seem less likely to have the hub ring, but the best indicator is to hold the disk up to a bright light and see how translucent the magnetic material is. A DD disk will usually show zero evidence of the light through the disk, while most HD disks will allow a definite hint of the light to show through. The material is chearly much thinner - i.e. the magnetic coating.

Best bet immed is to try to clean the head.

Geoff
Click to expand...
Thanks! Since EVERY disk gets the error, I lean towards the drive, again, but strange that it happened with the replacement drive, as well. The PC I bought for the drives actually has 2 5.25" drives that the seller was very adamant about them being good. (He is an active person on some vintage PC forums and I think he trustworthy) I might try the 2nd drive from that PC and see.

Have you every had an experience of this kind of error but the problem is the ribbon cable/motherboard?
 
Regarding cable/mb, if the disks are ok, as seems possible, then suspicion is back to the head, but might also be the sensors on the drive. One relates to disk present, another I think is for disk spinning. These sensors can be affected by dust seposits, this can be often cured by sharp blows both sides of the disk slot. The drive may seem clean, but dust can still collect. Blow as in puff of wind, not blow with a hammer!

Do you get the error immed on starting the format, on evet immed on accessing the disk, or does it seem to do the format and then give the error. Are you doing FORMAT /s to put the system on?

Geoff
 
I run format or format /s. It will first acknowledge it is a 360k disk and auto select to format as such. Then, it will say formatting, run a few seconds and then state it failed with the message I typed earlier. It then prompts if I want to format another.
 
OK, thanks for the detail. So, it's tried to format the first track, had a problem, retried, then failed. It could be the disk, but if you get the same thing with a selection of disks, it's unlikely. Could be the head, so it tries to write and then the immed verify fails, or it still could be the sensor so it's not getting the usual signal back which it interprets as the disk being bad. I've had this trying to use a disk drive in offices where the floppy is not normally used, and a sharp blow or two has got the disk working. I think more of a problem with 3.5" disks, but I've had similar with 5.25".

A cleaning disk would be a big help, but not sure you can get them now. I've got some cotton buds on long sticks that would do the job, reaching in far enough to get IPA to the head. 15cm long. The head would be 12cm in from the front of the drive. Both above and below the plane of the disk slot. If you try to make something with a normal short cotton bud, NO METAL! Wood or plastic.

Geoff
 
I had purchased cleaning disks (3.5" and 5.25") and I have run that through numerous times. So, I think I'll pull the drive and give a good cleaning. I appreciate our help!
 
Back in the day, the cleaning disks sometimes came with a little bottle of IPA or similar. You could get some drops onto the actual cleaning surface, which was slightly absorbent. If the ones you've got ARE absorbent then you might try this, but not if not absorbent.

Geoff
 
GeoffB17 said:
Back in the day, the cleaning disks sometimes came with a little bottle of IPA or similar. You could get some drops onto the actual cleaning surface, which was slightly absorbent. If the ones you've got ARE absorbent then you might try this, but not if not absorbent.

Geoff
Click to expand...
This kit also came with a dropper, so I used that each time
 
Gr8Britton said:
This kit also came with a dropper, so I used that each time
Click to expand...
I find I have to wet the entire track where the head is located if there's some badly shredded diskette on the heads... And sometimes just have to soak it with IPA with a cotton bud to get it clean.

Shredding floppy disks usually cause disk damage too. Have a look at the disk surface carefully, both sides, for any signs of lines or tracks appearing on the surface. It should have a uniform appearance.

Once a disk shreds, it's like a house of cards. It damages the next disk, which now shreds, and so on.
 
I have now tried all three 5.25" disks and all of them have the same symptoms. Also, I left the Sinclair disk in as A: and put in one from the other XT PC as B: and both are accessible. However, same symptoms. For giggles, I even try flipping the floppy ribbon cable to see if I had it backwards and had the same symptoms. I'm thinking it may be the motherboard.
 
So, I decided to remove the NEC V30 and FPU chips just to get back to the basic setup. this gave me a chance to pull the MB, clean it a little (not much needed) and then put it back together. The original Drive now read the contents of my DOS boot disk. I just formatted a disk (that it couldn't read before) and that was successful. So, it was either an issue with the NEC V30/FPU or just re-seating everything. Oh, I also had notice one of the metal connectors on a RAM slot looked like it had been pulled out. I gently pushed that back into place, but I don't it had anything to do with fixing this issue.
 
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