1541 Alps drives can't read a particular disk

Disk drives, Monitors, SuperCPU etc.
rmzalbar
Member
Member
Posts: 257
Joined: Wed May 08, 2019 9:06 am
Contact:

1541 Alps drives can't read a particular disk

Post by rmzalbar »

I have a disk that reads fine in my three Newtronics drives, but is unreadable in both of my Alps drives. The disk itself is a boxed copy of Planet X2 from David Murray, presumably minted on one of his 1571 drives.

In either of my Alps drives, attempting to load directory, asterisk, or any file causes it to try for about 1 second (flickering activity light) and then immediately stop with blinking light, which reports a read error. Similar to what happens if you try to read an unformatted disk.

However, all three of my Newtronics type drives read it perfectly.

It's appears to be a normal dos disk - no custom format appears to have been used, for maximum compatibility with turbo carts and such. So I tried making a normal DOS copy of the disk - with a Newtronics drive - and the copy reads just fine in the Alps drives.

I wouldn't expect an alignment problem in both Alps drives, as they both work fine on all my other disks - including commercial disks - and my experience with alignment problems is that they manifest as retries separated by chattering track 1 seeks. Nothing like that here.

I'm thinking there must be some difference between Alps and Newtronics that is overlapping with something in the format of this disk, but what could it be? There should not be any difference. My curiosity is making me sore!


Smooth operator
rmzalbar
Member
Member
Posts: 257
Joined: Wed May 08, 2019 9:06 am
Contact:

Re: 1541 Alps drives can't read a particular disk

Post by rmzalbar »

Nevermind, I discovered the issue. The disk isn't spinning. There is a defect somewhere in the jacket which doesn't allow the media to slide in the rearward direction quite far enough, so the disk is jamming in the jacket when clamped. The newtronics gate mechanism doesn't force the jacket quite so far in.
Smooth operator
User avatar
Gyro Gearloose
Member
Member
Posts: 471
Joined: Sun Nov 15, 2015 5:20 am
Contact:

Re: 1541 Alps drives can't read a particular disk

Post by Gyro Gearloose »

That's definitely an interesting story. It might indicate some new failure mechanism in the decades-old floppy mechanisms these days.
Maybe a spring or lever or something isn't doing its job anymore. Or maybe a bad batch of disks?
Did you contact David?
The price one pays for pursuing any profession, or calling, is an intimate knowledge of its ugly side.
rmzalbar
Member
Member
Posts: 257
Joined: Wed May 08, 2019 9:06 am
Contact:

Re: 1541 Alps drives can't read a particular disk

Post by rmzalbar »

It's a bad disk. I could see by the center hub that there isn't nearly as much rearward movement available as there is in the other directions. I cut the rear flap open - it was glue intrusion into the liner. This appears to be an Athana disk, the most commonly available. I have a few boxes of these as well as some loose ones from floppydisk.com. I pulled a few of these from the stack and found another with the same issue.

I was able to transfer the label (with the help of a hair dryer) to a good copy.

The issue with the Alps is just that the push-down gate has two metal tabs that closely confine the jacket. The Newtronics with the little swing-gate has more tolerance.
Smooth operator
User avatar
motrucker
Member
Member
Posts: 191
Joined: Tue Jul 21, 2015 6:11 pm
Location: Maryland, U.S.
Contact:

Re: 1541 Alps drives can't read a particular disk

Post by motrucker »

I've seen this happen on some 5 1/4" disks over the years. Generally speaking the 5 1/4" disks seem to age better than their 3 1/2" counterparts though.
Oddly enough I don't believe this is an age related issue.
C-64, C-128, and Amiga A2000 user
User avatar
Gyro Gearloose
Member
Member
Posts: 471
Joined: Sun Nov 15, 2015 5:20 am
Contact:

Re: 1541 Alps drives can't read a particular disk

Post by Gyro Gearloose »

Huh. Interesting. Are these Athana disks recently made? Like this millennium?
The price one pays for pursuing any profession, or calling, is an intimate knowledge of its ugly side.
rmzalbar
Member
Member
Posts: 257
Joined: Wed May 08, 2019 9:06 am
Contact:

Re: 1541 Alps drives can't read a particular disk

Post by rmzalbar »

Not sure. The sealed boxes I have were made in 93, but the loose bulk disks I looked at came from floppydisk.com and I don't know how old they are. I don't think it's age-related - the glue is totally solid, it seems to have been some sort of plastic solvent glue, welding the plastic together. I wasn't able to break the bond - had to cut the jacket. It looks to have been inconsistently applied and was squished into the jacket while being glued and pressed closed during manufacture.
Smooth operator
Post Reply Previous topicNext topic

Who is online

Users browsing this forum: Google [Bot] and 15 guests