Do you have a terminator INSIDE the machine at the end of the cable? Some Macs have dual SCSI Controllers. So if you have a CD and a Harddrive on the internal SCSI Chain, you *might* need to add a 50-pin SCSI Terminator INSIDE the machine at the end furthest away from the board connector. especially if it has two SCSI Controllers.
I have had this issue before on a PowerMac 8600. Where the internal SCSI Controller was not terminated at the end. I fixed that by rooting around my room for a small internal SCSI Terminator. After that, it was all hunky-dorry and worked like a charm.
You can find the terminators on ebay for almost a dime-a-dozen. So have a look there. Also, if you use the terminator INSIDE the machine, you need to have all the other drives non-terminated so to make sure you don't terminate the bus before the last device. This could cause simple problems such as the device after the terminated device simply not working, down to more complex issues of system instability.
Just some helpful hints.
I have had this issue before on a PowerMac 8600. Where the internal SCSI Controller was not terminated at the end. I fixed that by rooting around my room for a small internal SCSI Terminator. After that, it was all hunky-dorry and worked like a charm.
You can find the terminators on ebay for almost a dime-a-dozen. So have a look there. Also, if you use the terminator INSIDE the machine, you need to have all the other drives non-terminated so to make sure you don't terminate the bus before the last device. This could cause simple problems such as the device after the terminated device simply not working, down to more complex issues of system instability.
Just some helpful hints.