mine is 68 pin with an adapter with active termination plugged on the end,without the termination the drive didnt show.
Some (most?) wide drives will refuse to negotiate in narrow mode unless some bias voltage is present on the high byte lines. It's not termination that does the trick but this bias voltage, so a wide-narrow converter with active high-byte termination will coincidentally do the trick nicely.
Seagate drives worked great with simple, cheap passive converters. Western Digital ones were a different story.
The obvious trick to overcome the problem if only a passive adapter is available is to place the drive last on the bus and enable the drive's own termination and termination power. Not a real solution with three such drives
dougal said:
The HDD is spinning up when powered as it is. Would a jumper on mtr help ?
MTR will simply not spin-up the drive until the START command is send from the host adapter, it's not even a particularly useful setting in this case.
As Beavis said, don't keep your hopes up with SCA drives. They may sell for next to nothing and seem good bargains and all that, but they're tailor-made for hot-swap enclosures who take care of any and all settings, so these converters really only work well in wide SCSI environments, with external active terminators.
There's no way to force a bias voltage on the high-byte lines without hacking the drive itself, since by design SCA drives eschew termination options, so if the drive refuses to negotiate in narrow mode it's a no-go. That said, this is a Seagate drive so chances are it behaves well in narrow mode. Assuming that, the problem must be in termination/termination power, which as said is absent with SCA drives.
So you will need an external active terminator AND a way to supply termination power to it, because neither the Seagate SCA drive nor the antiquated Supra controller will provide it because the SCSI-1 standard it follows only requires passive termination. The easiest way to supply termination power is by means of another, non-SCA, single-ended drive, but a) you can't have two drives in the Supra and b) if you had one there'd be no need to use the SCA one in the first place. So if you MUST use this one, you'll need to hack termination power onto the SCSI bus somehow.
Bottom line: SCA is a bad idea. Get a regular 50-pin drive.