Re: Help... 3.5 Disk Drive Dead

[rubywand@aol.com]

In article <19970120145200.JAA22244@ladder01.news.aol.com>, cptfa@aol.com
(CPT FA) writes:

>
>My 800K, 3.5 Disk Drive is no longer working on my IIGS.  When a disk is
>inserted the drive tries to read it and then locks up the entire system
>forcing me to do a 3 finger reboot.  Any suggestions where to start
>troubleshooting? ....


     The most common cause of "bad drive" problems is heads which are
gunked-up and/or misaligned. A drive which has become partially unplugged
from the computer can, also, look bad as can one which has a bad cable.

     Incorrect accelerator settings, interference from AppleTalk,
interference from any background task are some non-drive factors which can
make a drive look bad.

     Normally, genuine "bad drive" problems first show up as diskettes
which the computer says it cannot read or as frequent "cannot load ProDOS"
messages when booting from the drive.

    The symptoms you describe are not typical first indicators of a bad
drive.  A defective drive may cause the system to hang if a series of
files is being loaded and one of these is misread. If execution of the
software has begun it may not allow normal error reporting and just hang.
The drive _may_ be a fault; but, better suspects are the diskette, the
software, NDA's, Inits, low-memory, etc.. 

     The way to decide whether or not your drive is the source of your
problems is to test it under simple, clear-cut conditions.
  

Things to try for a "bad drive"

     Try cleaning the heads using a Cleaner Diskette (from Radio Shack,
etc.). Check under ProDOS 8 by inserting a varienty of non-protected
known-good diskettes and doing CAT's.
  
     If cleaning does not seem to help, try wiggling the drive cable while
attempting to CAT a known-good, unprotected diskette in the drive. If
wiggling helps, you are likely to have a partially unplugged cable, a bad
cable, or a GS drive socket with a loose connection to the motherboard.

     Try formatting a diskette. A drive which can format and R/W diskettes
it has recently formatted but cannot read most other diskettes probably
has heads which have become misaligned.

     Set your boot Slot to Slot 5 and try power-up booting a couple
bootable ProDOS diskettes known to be in good condition. If you can boot a
variety of disketts, including commercial game, etc. diskettes, the odds
are pretty good that your drive is okay. 

     A 3.5" drive that, after cleaning, cannot boot known-good diskettes
is likely to have screwed-up heads. However, it's a good idea to try
unplugging and re-plugging the drive (with the computer OFF) and, then,
try another boot.

     If you have a 5.25" drive attached, boot ProDOS from the 5.25" drive
and try some CAT's of non-protected known good 3.5" diskettes in the 3.5"
drive. As earlier, do the cable wiggling test while attempting the CAT's.

     One reason for doing so many tests away from GS/OS is that there
seems to be a bug in some versions of system software (including the
latest) which, every once in a while, causes Slot 5 3.5" drives not to be
recognized unless you have a diskette in Slot 5, Drive 1 when you
power-up. (This may, really, be a RamFAST firmware bug-- I do not know.
Fortunately, the glitch is fairly rare.)

     A very good test is to try out the drive on a friend's IIgs or IIc+.
If it continues to bomb, it is likely to have R/W heads which have become
badly misaligned, heads which are badly worn, or heads which have been
partially dislodged from the mountings.

     The 3.5" drive's heads are held in place by springy metal sheets.
Unlike the mounting for the 5.25" Disk ][ head, these are fairly delicate.
If anyone has tried cleaning the heads by sticking in an alcohol swab and
'swishing around', there is a good chance the head mountings are messed
up.

     Shops which replace heads are fairly rare. I had this done a few
years ago and the drive still works fine. However the charge is around
$80. It is cheaper and easier to get a good 2nd-hand drive at a swap-meet.
You can, also, look for a bargain Mac drive and do a "transplant" as
described by Steve Buggie in the Winter issue of II Alive.

     Steve Buggie (a.k.a. "The Disk Guru")  is a good source of
information on drive repairs. Check out some of his recent posts to this
newsgroup.


Rubywand