9500 Woes

[mac2geezer]

A 9500/150 here, a known good HD installed internally , the machine gets to the happy Mac and goes no further. The same drive in an external enclosure connected to the external SCSI bus, the machine boots right up. New mobo installed, nothing changes. With the HD in the external enclosure and the machine booted into 9.1, System Profiler says the HD id is 0, the CD id is 3, so it does not appear to be an id conflict.

Could this be as simple as a bad ribbon cable? I can't think of anything else after changing the mobo.

 

[equill]

It seems that you have a valid System Folder on the drive if it can boot the Mac when the HDD is used as an external startup volume. However, internal and external buses are separate in the 9500.

External bus (including its controller) and termination seem to be functional. Given that the HDD is terminated correctly on the drive, and was not getting termination from the external enclosure, and that the HDD is not only the terminal device in the internal daisy-chain, but also has TP enabled (termination power supplied by the drive, if the HDD has that option) it should work.

It is unlikely, but not impossible, that the internal bus controller might fail, but the internal controllers of two MLBs? It seems rather that yours is a cabling, a connector, a PS (or termination power to the bus), or a position problem. Do both drives, especially the HDD, spin up? Have you jumpered TP (termination power) on the CD-ROM? Can you boot the Mac from the internal CD-ROM?

de

 

[mac2geezer]

Thanks for the help.

The drive works if it's not the last device on the chain, so it's obviously a termination problem. I have the pin diagram from the Seagate site but have not hit on the right combination of jumpers yet. Gave up for tonight but will have another look at it tomorrow.

If nothing else, I'll just put that drive in the middle of the internal chain and leave it at that.

 

[equill]

What model of Seagate is it? There are consistent jumpering needs throughout their range of models, and some needs that are peculiar to Wide as opposed to Narrow, or LVD as opposed to single-ended. Seagate is both clear and consistent in its documentation, but, as a generality for Macs, you need TE for the ultimate drive in the chain, TP from the drive, and can mostly ignore PE or PD, WP, DS, ME and, of course, SS or RES. In Macs you could go a lifetime under SCSI and never use more than TE and TP, in addition to the SCSI ID settings

Other makers (IBM/Hitachi, hp, Fujitsu, Quantum and so on) can have more and differing needs from model to model, but that is not your concern here.

de

 

[mac2geezer]

It's an ST15150N. I've tried jumpering termination enable alone, term power from drive alone, and both together with no luck. Also, a drive that works fine at chain end in the 8600 exhibits the same problem in the 9500. I tried a different ribbon cable in the 9500, no change.

The drives all spin up and sound like they're being accessed until the happy mac then silence. The CD drive does not appear to be terminated.

 

[coius]

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.

 

[mac2geezer]

Thanks to both of you for the advice. I finally gave up on the ST15150 as a chain end device and put an ST34371WC with a 50 pin adapter there, and the ST 15150 is in the middle of the chain. All is well with that configuration.

The only 50 pin terminator I have is one of the Centronics 50 external types but will have a look at e-Bay for some that will terminate a ribbon cable, for future use.

This SCSI stuff is kind of like networking; there's a little bit of magic involved and if you don't hold your mouth just right things don't work.