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Conference 7.286::atarist

Title:Atari ST, TT, & Falcon
Notice:Please read note 1.0 and its replies before posting!
Moderator:FUNYET::ANDERSON
Created:Mon Apr 04 1988
Last Modified:Tue May 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:1433
Total number of notes:10312

1034.0. "Drive scratches floppy" by HAMSUP::MARXSEN (Univ.Milky.Sol.Earth.FRG.Hamburg) Tue Dec 11 1990 08:21

    Hi all,
    
    a friend has following problem with a self-attached 5 1/4" floppydrive:
    
    This drive sometimes scratches his disks.
    This also takes place when the drive isn't used, standing by with a
    disk inserted.
    
    Now he read in an Atari-HW-book that a bad timed "Halt"-signal could
    cause this. Passing this signal over a monoflop would solve the
    problem.
    
    Do you know a "Halt"-signal at the Shugart-bus ?
    We don't !
              
    Any idea what they mean - or, have you another solution ?
    
    Thanks,
    		Detlef.
T.RTitleUserPersonal
Name		DateLines
1034.1try cleaning the heads....NOMUNY::WSC023::B_NOTTINGHAMBill NottinghamTue Dec 11 1990 17:4614

Detlef,

Everytime I have seen such a problem, it was caused by dirt or grit on one of 
floopy heads. Try cleaning  the heads with a cotton swab soaked on alcohol.
It may require you disassembling the drive. This would happen just by inserting
a disk since the floopy will spin with physical contact to the heads. 

I can't imagine a logic component causing a scratch in the floppy media...

hope this helps...

Bill N.
1034.2Magnetic scratch...HAMSUP::MARXSENUniv.Milky.Sol.Earth.FRG.HamburgWed Dec 12 1990 10:137
    Thanks, Bill !
    
    ...the disks get scratched magnetical not physical.
       We guess there is a spike on only-the-Lord-knows-which signal
       that causes the head to write nonsense on the position it stays.
    
    Detlef.
1034.3switch it off to write garbage...BACHUS::PIRLETThu Dec 13 1990 04:4820
     Hmm I think I know that problem. It took me quite a long time to
    realise what was going on... I finaly discovered that if the
    internal 3.5'' inside drive does not care, my external 5.25'' does
    get corrupted any time I switch of the power.
    
     If that is the problem, then it is possible to prevent the write
    signal to assert (go low) for some time with the residual power (in
    the filtering capacitors) if (for example) both drive select 0 and 1 
    is asserted (should be impossible condition), or if both read and write
    is asserted (another nice impossible condition).
    
     I did start such a project, then left it on the side. I just got
    carreful not to switch off with a loaded media in the 5.25'' drive.
    In fact I just open the drive any time I do not access it.
    
    
    	Hope that helps.
    
    	Louis Richard