🚀 go-pugleaf

Thanks for all who gave suggestions.

As an update, I've tried most of these, including not using SCSI Device 5,
having devices switched on and not switched on, and changing the chain of
devices.

In summary, it turns out that the scanner is the one causing the problem
and it effectively crashes the Mac if all four SCSI devices are connected,
regardless of whether they are switched on or off*, and regardless of
whether the scanner is the last or first device in the chain. My cables
don't exceed the maximum length.

> You could also try ALL TERMINATION SWITCHED OFF.

However, if the CD-R is the last device in the chain and switched off, the
system works. As the CD-R has active termination, the chain is in effect
not terminated. Is this okay, and if not will a manual terminator properly
terminate the chain even though the device is off.

The other possible solution is moving the external hard disk to the
internal bay (internal SCSI bus) of the 7500.

> This may be yet another red herring, but you indicate the presence of THRE 
> devices with "switchable active termination". 

All the devices have a switch, and I only have the switch on the last
device in the chain.

Thanks.

Mark
mark_ingle@ifep.demon.co.uk