[comp.sys.mac.hardware] HELP: Those old termination blues

biswa@hoff.berkeley.edu (Biswa Ghosh) (05/21/91)

Scenario:

Last week, I posted about some problems I was having with an external
Quantum 105 hard drive that I bought from APS. Basically, when I turn on the
drive with my computer still off, the drive doesn't spin up. It spins up only
at the moment I turn on the Mac, and so isn't recognized, and I have to mount
it with SCSI probe every time I power up the machine. I have narrowed it down
to something related to the termination (I think), but I can't fix it.

Details:

The mac is an se/30 running generic 6.0.4 with inits removed. It contains an
internal quantum 40 meg drive installed by Apple, with internal termination.
The external has an external terminator, and is connected to the mac with an
18 inch scsi cable suppled by APS. There are no other scsi devices.

Here's where it gets interesting. The external spins up immediately when hooked
up to my friend's se/30, so the problem is in my mac. Disconnecting the
internal drive from its scsi cable allows the external to spin up right away.
** Keeping the internal drive connected, but removing its termination allows
the external to spin up right away.**  I replaced the terminators on the
internal with new ones, but that didn't help. Things work fine only when the
internal's terminators are removed.


Questions:

(1) Is it safe to run with no terminators on the internal drive?

(2) The internal termination is supposed to be there, so something is wrong.
    Could it be the
	- internal drive
	- internal drive scsi cable
	- external drive 
	- external scsi cable or terminator
	- motherboard (Oh god, no, not that !! ;-0)

(3) What's the proper orientation for the termination strips? They have a
    little white dot on one end, and the pc board has a little arrow at one
    end. Should the terminators be inserted with the dot and arrow lined up?


All advice, tips, prayers, etc. appreciated!

Biswa Ghosh
550 Cory Hall				arpa: biswa@janus.berkeley.edu
U.C. Berkeley				uucp: ...ucbvax!janus!biswa
Berkeley, CA 94720			tel:  (415) 649-3636