Re: How to fix a Disk ][ 5.25 drive?

[Linards Ticmanis <ticmanis@gmx.de>]

On 12/19/2010 06:32 PM, Sam Latella wrote:
> Looks like my disk ][ has bitten the dust?  The drive light comes on and now
> just spins without reading anything on the 5.25 disk.  Any quick solution
> for a fix?  Would like to keep this drive working with not much cost.
> 
> Thanks in advance.

Firstly, absolutely don't put any important disks in there until the
drive is fixed, and verified as fixed. Apple drives have a fairly common
failure mode that causes them to be constantly in write mode, so that
it's unable to read or boot from disks and will overwrite any disk you
put in, even if it's write protected.

To fix a drive in this state, you'll need to replace the 74LS125 chip
that's inside the drive. Luckily this is a cheap and easy-to-get chip.

To prevent this failure mode from occurring in the first place, always,
when you plug the drive cable into the Disk II interface card, before
turning power on, make absolutely sure you didn't misalign the
connector. The fault is caused by sending 12 Volts to a line that's only
meant to handle 5 Volts.

-- 
Linards Ticmanis