Long SCSI chain - freezing?

[Syntho]

I'm having some weird problems. My CDROM is freezing me and I think it has to do with termination. I seemed to have had to leave my SCSI HD actually connected with the SCSI cable to not freeze (but I disconnect the power). That gets the proper termination going on SCSI ID 0 I think. Then after that I have a CDROM on ID 3, another CDROM on ID4, and then comes the Zip drive which is terminated.

I also see my SATA HDs but it says that's on SCSI Bus 2. The other chain above says SCSI Bus 0.  Here's how I've got it hooked up:

SCSI Bus 0:

(no ID) - SCSI HD, terminated, but with power unplugged
ID3 - CDROM, unterminated
ID4 - CDROM, unterminated
ID5 - Zip, terminated

SCSI Bus 2 (SATA card, automatically fills in IDs)

ID0 - SSD
ID2 - 1TB drive

On the SCSI Bus 0, the ID3 CDROM seems to want to be terminated sometimes. I tried the exact rig as posted above but with the ID3 CDROM terminated as well, but no go.

This is turning into a SCSI Labyrinth!

I'm going to go tinker around some more and see what I can come up with.

 

[Macdrone]

Ok on what type of Mac?

Age , capacitors or straight up chips starting to fail or SCSI black magic could cause this.

Have you terminated one at a time and tried? Then two at a time switching termination ends?

I have 5 devices on my color classic and as long as the last on the chain is terminated there are no issues.

CDROM, jaz, zip, orb, apple external hard drive. I usually leave the zip on the end as it's the lightest and easiest to move.

 

[Syntho]

I'm on a 9600 with OS8.6. I think the issue is mainly due to me disconnecting that internal SCSI drive. The CDROM is ID3 so it should be terminated when the SCSI HD is disconnected. The Zip drive is ID5 so it should also be terminated. That should be my ticket, but it doesn't seem to clear up the freezing issue.

That's why I mentioned the SCSI Bus 2. 9600s have a SCSI Bus 0 (internal I think) and SCSI Bus 1 (external SCSI). The 9600 seems to augment those two with SCSI Bus 2 when you use a PCI SCSI or SATA/IDE controller. And since I've added a SATA card, the two SATA HDs show up as ID 0 and ID 2, with those IDs being assigned automatically. I'm thinking that those two drives might be interfering with the internal SCSI Bus 0 or something seeing as it's assigning them IDs automatically.

 

[Syntho]

I just read briefly about an internal pass-through SCSI terminator. My rig works 100% when I've got that SCSI HD in there which is obviously terminated, no freezing when loading CDROMs. But no matter what I do when I disconnect it, I freeze.

I'm thinking that the CDROM's termination isn't 'good enough' and that I'll need one of those internal pass-through terminators, or something like that.

 

[Syntho]

EDIT - never mind, brb!

 

[Syntho]

Disregard this thread. The supposed termination jumper on the Zip drive was crammed between the first row of pins and the plastic on the side. As soon as I took it out there and put it on the actual termination pins, it's all working fine now wth the SCSI drive disconnected.

 

[Macdrone]

Told you check the devices one at a time.  Good job.  I am glad you found the issue.  The SATA by the way should have no issue or bearing on the SCSI chain.  Also the added scsi card should not either.  The added scsi card is independent of the motherboards scsi.

 

[techknight]

I remember the good old SCSI Voodoo. Of course I never really got attacked by it except in special cases. 

 

[Macdrone]

Adding a new non apple SCSI hard disk always brought the worst voodoo out.

 

[techknight]

The voodoo I have encountered in the past, has been crappy cables. There are SCSI cable thicknesses of all kinds, and the thinner cheaper cables of the day caused me grief. More fun was the CMS HDDs that had the regular 25pin SCSI connectors than the more common centronics.