🚀 go-pugleaf

Mark Ingle wrote:
> 
> 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

SNIPPED

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

Another possibility for you!

At work we bought a couple of external syqyest drives a while ago and I am 
sure that as delivered, they had termination BUILT-IN.  The instructions 
told us that "if you are unable to put the unit at THE END of the SCSI chain, 
you have to partially dimantle the init to gain access to two special banks of 
terminating resistors and REMOVE them carefully".  Have a look at your 
manuals and see if any of your devices that haven't got the external 
termination ON/OFF switch, have actually got internal terminations.

If the system seems to work OK without the CD-R turned on, yet that is teh 
device with the so-called active termination set to on, it certainly sugests 
that somewhere in the chain there must be a device which is terminating.  
Identify that unit and arrange to have it at the end of teh chain, then turn 
off the CD-Rs termination.  This might sort you out.

Steve Parker

 ====================/
  Stephen R Parker                 /
 steve@parkfish.demon.co.uk /
 ====================/