powermac 7200 hdd

Bill Germer hfs-interest@ccs.neu.edu
Wed, 09 Aug 2000 16:33:16 -0500

on 8/9/00 10:22 AM, michael.conry@softhome.net at
michael.conry@softhome.net wrote:

> I am not sure if this is exactly on-topic, but i would be
very grateful of any
> help you can offer. Basically, i think i have crippled
the scsi controller on
> my boss's powermac 7200. (This occurred while trying to
hook up an external
> scsi cd-writer to do some file movement to his new
machine. I turned the
> burner on during boot, and also had it terminated. Both
these are no-no's for
> the machine (although i am consoled by others that scsi
SHOULD be hot
> swappable, and termination should not damage hardware).
Local mac expert could
> not get it to boot off cd, so looks like controller is
> Anyway, i have no access to other macs, and no way of
knowing if the hdd is
> intact or not. What i do have is my linux box (Dell
precision 410) with
> Adaptec 2940 U2W and Adaptec 2940 UW SCSI controllers on
the motherboard. I
> know from reading around, that it should be possible to
mount the disk if i
> can get it to work in the pc. what i don't know is how
safe it is to do
> something like this (is the disk real scsi). Will i end
up with two broken
> machines rather than one if i connect the drive to the pc
controllers?! Things
> like the apple advice not to terminate external devices
due to the internal
> hard drive being terminated do not give me confidence
(seems at odds with all
> other scsi advice i have found).
> I understand nobody can guarantee anything, but if anyone
subscribed to this
> list thinks they know something relevant (like that i
should not even think
> about this) then i would appreciate the advice.
> thanks
> michael


Before declaring the 7200 dead, there are a few thing you
might want to try.  First of all the last external SCSI
device and first internal hard drive  must be terminated
and all device in between unterminated.  The external drive
should not use an id of 0 or 3,  0  is for the internal
hard drive and 3 is for cd-rom drive.  Turning on an
external drive while booting the computer usually will not
damage the SCSI hardware but will corrupt the scsi driver
on the boot disk, this will leave you computer unbootable
an unusable.  To reinstall the driver can be tricky. 
First, disconnect all eternal SCSI devices. Remove the
cover top the 7200 and disconnect  only the molex power
connector to the hard drive, leaving the scsi cable
attached.  Start up the computer and insert  a bootable CD,
then restart the computer and hold down the 'C' key.  At
this point if the computer boots from the CD then all will
be well.  

If the computer stops with a blank grey screen and won't go
any further then there is probably some damaged hardware. 
Try disconnecting the scsi cable from the hard drive and
restart your computer.  If you still get the blank grey
screen then disconnect the cd-rom drive and restart. If you
still get a blank grey screen then the motherboard is
probably bad.

If the computer stops with a grey screen and a '?' in the
middle of the screen, then the computer is looking for a
bootable disk.  Make sure that you CD-rom disk is a
bootable cd and it has the Mac OS Installer program and
Drive  Setup program on it.  If the computer still will not
boot then you will have to get a bootable floppy to
continue.  You will need the Disk Tools disk for the 7200.

After booting you computer with CD or floppy and waiting
for all disk activity to stop, plug the power for the
internal drive back in.  Wait 30 seconds for the disk to
start up then launch the Drive Setup program located on the
CD or floppy.  The program will display a window with a
list of drives, hopefully you will see two drives.  One at
ID 0, the internal Hard drive and one at ID 3, the CD-rom. 
Click on the the ID0 disk  to highlight it then select the
"Functions" menu and drag down to "Update Driver".  If all
is well the you will get a message "Your new driver will
not be available until you restart.".   At this point
restart you computer from the CD and run the DiskFirstAid
program.  If the "Update Driver" option is greyed out and
is not selectable then the disk was probably formatted with
something other that an Apple utility.  You will  have   to
update the  hard disk driver with a program  like the FWB
Hard disk tool kit or APS tools.

Bill Germer
Computer Technician
Shorecrest Preparatory School
Saint Petersburg Fl