I was about to ask about SCSI termination power. Cool that a topic opened up about this.
Short form:
Any good references out there on the web about SCSI termination? Any ideas how a logic board can permanently damage a SCSI HDD?
Long form:
I have a logic board that seems to fry SCSI HDDs. I can take a newly-found SCSI HDD and attach it to the internal SCSI port, boot the system from an external Zip drive, and initialize/format/test the new SCSI HDD using 7.5 Drive Setup. But once I disconnect the new HDD, no system can use the HDD again.
Once affected, an HDD spins up, spins for about two seconds, then spins down. FWB Toolkit reports that the drive responds (FWB and SCSIProbe can both access the manufacturer data page) but nothing can start the drive. FWB reports "Check Condition" errors on the damaged drives. Drive Setup does not count the drive as present (doesn't find it at all).
The logic board's internal HDD power jack is providing clean power, +5.09, +12.09, and no difference in grounds. I see no bent pins, any obvious issues.
There is one drive that has survived this logic board, a 426MB Seagate with active termination. But even it requires the (terminated) Zip drive on the external port before it will come up. The logic board has damaged two Apple-branded Quantum drives.
The Seagate has jumpers to select termination power from itself, from the bus/host, etc. I am not sure which is correct for Macintoshes, and whether it matters if it's internally or externally attached. (I suspect if I choose the right setting, the Seagate will work without the Zip drive.)