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Warning! Catweasel-modded PC-5.25"-drive may destroy your 1541 disks!

If you own a Catweasel controller for your Amiga or PC, I have to warn you
that the drive modification recommended on Jens Schoenfelds' homepage
necessary for reading 1541 disks are dangerous for your datas' health!

The homepage says, you have to modify the drive so it can read the second disk
side for c64 disks. Well, that's true, but the modification itself is
dangerous for your data - you are advised to glue a magnet and a reed contact
to the drive motor / and nearby the drive motor.

Sounds all fine, seems to be too "inside" (Track 40, eh?) to do any damage to
the data, but when you actually _insert_ a disk, the motor with the
data-deadly magnet is already spinning, thus the magnet is moving dangerously
near your data...

I lost some of my best utility disks this way. They now contain 23 read errors
all over the place. Typically, they contain one 23-read-error every track
between track 6 and track 20. This supports my theory that these errors occur
as soon as the disk is inserted into the modified PC disk drive.

I found out that when transfering with Star Commander, I had had much fewer
read errors (but I tried other disks with SC first). Rechecking with a real
c-64 the acutal transfered disks, to my dismay the readerrors displayed by the
Catweasel transfer tools actually were now really there!

Thus my recommendation is to modify your PC drive another way. Mounting a
magnet inside a disk drive is no good idea, whatsoever. 

I'll inform Jens soon.



0
ATT
8/6/2005 7:25:48 PM
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ATT wrote:
> If you own a Catweasel controller for your Amiga or PC, I have to warn you
> that the drive modification recommended on Jens Schoenfelds' homepage
> necessary for reading 1541 disks are dangerous for your datas' health!
> 
> The homepage says, you have to modify the drive so it can read the second disk
> side for c64 disks. Well, that's true, but the modification itself is
> dangerous for your data - you are advised to glue a magnet and a reed contact
> to the drive motor / and nearby the drive motor.
> 
> Sounds all fine, seems to be too "inside" (Track 40, eh?) to do any damage to
> the data, but when you actually _insert_ a disk, the motor with the
> data-deadly magnet is already spinning, thus the magnet is moving dangerously
> near your data...
> 
> I lost some of my best utility disks this way.

Might it be that you used too big/strong magnet piece?
0
silverdr
8/7/2005 10:44:54 AM
This might be a longshot, and maybe some people may come to the 
conclusion that I have no idea what I'm talking about.

Can't you use an electro magnet instead of a permanent one, one with a 
comparable magnetic power? This way you can hook the magnet up to the 
drive door which powers on the magnet when the door is closed.

-R-
0
Jurgen
8/8/2005 8:20:46 AM
Jurgen Haan wrote:
> This might be a longshot, and maybe some people may come to the 
> conclusion that I have no idea what I'm talking about.
> 
> Can't you use an electro magnet instead of a permanent one, one with a 
> comparable magnetic power? This way you can hook the magnet up to the 
> drive door which powers on the magnet when the door is closed.

Might get difficult to wire the coil located on a rotating base...

Actually the best (which I thought of) way to do it would probably be to 
use optical method with a black-matte adhesive tape attached to the side 
of the rotating cylinder and a small piece of reflective one. Similar to 
what Video 2000 VCRs used to detect EOTape. That's the way I once wanted 
to do the mod but then, of course, never did... ;-)
0
silverdr
8/8/2005 4:42:38 PM
Okay, I did a systematic research into the matters of Catweasel suspected
problems. 

The first problem I encountered was that it even seemed to be unreliable to
simply display the 1541 disk directory via the PC and Catweasel. Sometimes,
the directory would show up, sometimes not. (Well, not to mention the false
alarm about lost data on 1541 disks - it turned out to be the fault of a bad
PC disk drive.)

When exchanging the PC 5.25" floppy disk drive, these problems were gone.

Then I decided to add the magnet and reed contact to the new PC floppy disk
drive.

Suddenly, I got reading problems again ; thus, I conclude my reed contact is
somewhat inadequate and misses the rotating magnet many times. I do not have
an oscilloscope to verify this hypothesis, but I'm quite sure.

If someone can recommend a certain brand of reed contacts in order to properly
modify the PC floppy disk drive, please let me know; please also let me know
if there is another way to modify that drive so it can read both 1541 disk
sides. 

I spent over 9 hours to come to this conclusion; I tried several disks,
several PC drives, I re-checked the data validity on the c64/1541, etc.

Sorry for the inconvenience. Any advice is greatly appreciated. Alas, I also
couldn't find any link of how to avoid the "Reed/magnet"-solution and use
something more reliable?


0
AT
8/9/2005 7:17:39 PM
Reply:

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