: scsi woes


minstrel
Sep 9th, 2002, 04:27 PM
Hello, everyone.

I own an oldie but a goodie...a PM6100/66. I'm running system 8.6 with 136 MB RAM. I've got a 7 bay tower connected with three HD,a CD Reader and a CD burner After a recent disconnect for redecorating, my Mac won't boot with the tower connected, but will boot with it disconnected. Even if only one hard drive is left connected in the tower, it will not boot. Am I correct in assuming that I've somehow fried the SCSI port on my Mac? Is there another explanation? How might I troubleshoot?

Any help would be greatly appreciated.

Trevor Morris
Sep 9th, 2002, 04:50 PM
I would guess that the scsi cable attaching the jukebox to your system got damaged.

Some SCSI cables are stupid fragile.

The 6100 only has a single scsi bus, if the system will boot off the internal scsi drive your SCSI bus is fine.

Try another SCSI cable before you do anything.

minstrel
Sep 10th, 2002, 09:58 AM
Good morning, Trevor.

Thanks for your reply. I forgot to mention that I bought a brand spanking new SCSI cable, and there was no change to the problem. With the external tower attached, on startup, I get chimes, then the mouse arrow in the upper left corner of the desktop. No happy Mac. This is true whether I have all five drives attached, or only one drive attached in the tower. Without the external tower attached, my baby boots up just fine.

Any other ideas?

Steve

Mississauga
Sep 10th, 2002, 10:53 AM
Steve,

Are you sure your SCSI ID #s are in order... or the selected startup disk hasn't changed? Have you booted from a utility CD and run some tests?

Strongblade
Sep 10th, 2002, 12:37 PM
It does indeed sound like a SCSI conflict, but it's peculiar that ALL his devices would give a SCSI conflict, unless they have somehow all shifted to the same number.

You can verify the SCSI IDs are different by checking the jumpers on the HD itself. Alas, ther eis no precise standard on where to find such jumpers, but you will usually find many pins, in two rows and maybe, in small print near them, the leters J00 J01, J02... Sometimes the J is replaced with an A.

There are often charts on the drive displaying what jumpers are what.

minstrel
Sep 10th, 2002, 01:14 PM
Thank you for your input!

I'm trying to figure out how my ID's could have changed. I know I committed a SCSI cardinal sin; I changed the ORDER of connection of the three hard drives in the tower. However, I did not change the ID jumper settings. That made me think it was a termination problem. But, if it was termination, why would the problem persist with only one HD connected to the SCSI cable inside the tower? I've got an external terminator that I had been using. I've tried connecting with termination, without termination, reversing the order of connection, you name it. The only thing I made sure I didn't do is change the ID jumper settings.

Truly perplexing.

Steve

MacDoc
Sep 12th, 2002, 02:34 AM
Many times the terminators on the individual drives are not turned off or removed ( resistors with pins ) and some drives have active terminators that do not like being in the middle of anything. Despite the rules scsi can be Voodoo :rolleyes:
ALL drives should be unterminated in this chain.

minstrel
Sep 12th, 2002, 09:56 AM
Good morning,

Thanks again for all your input.

Macdoc, is there any way I can tell if the drives are actively terminated? The two of the three HD are IBM, and require jumpers for termination (according to their cases). The third is the original Apple HD from my 6100. I also have a CD reader (I don't know the brand) and the burner is a HP Surestore 2X6.

Steve

MacDoc
Sep 12th, 2002, 11:05 PM
Did you just move up in OS - if so the HP is your problem. They had a firmware issue with their earlier products that locked everything up past a certain OS point.
The original Mac drive will have terminating resistors along an edge and may have a jumper called TE which will enable it.

minstrel
Sep 13th, 2002, 12:24 PM
Macdoc,

Thanks for the suggestion. I'll check the Apple drive. I don't think that is the problem, because the tower won't boot even without the Apple drive connected.

I haven't changed OS since I upgraded to 8.6 over two years ago. Until I moved the computer about four months ago, and switched the order of the HDs in the tower, I had no trouble whatsoever.

Oh, well.

Steve

Strongblade
Sep 14th, 2002, 03:03 AM
SCSI Magic.

Have you tried the exorcism dance? You need a bamboo stick, two incense burners, incense (preferably apple-scented) and some strange mood music from Brazil

Set the drives in a circle and dance around them, gently bopping them with the bamboo stick. make sure incense is lit and burning well.

It's worked for me, twice, so it *MUST* be the right thing to do.

;)

:cool:

Rob
Sep 14th, 2002, 11:41 AM
I am assuming you had the SCSI tower powered up when you were booting. What happens if you leave the tower off until the boot cycle is complete and then turn on the SCSI tower?
Termination power can sometimes be a problem too. I can't remember if the 6100 provides termination power to the bus. If it doesn't, then one of the SCSI devices must provide it. Not all of them do however.

PosterBoy
Sep 14th, 2002, 05:01 PM
<BLOCKQUOTE>quote:</font><HR>Originally posted by Strongblade:
SCSI Magic.

Have you tried the exorcism dance? You need a bamboo stick, two incense burners, incense (preferably apple-scented) and some strange mood music from Brazil

Set the drives in a circle and dance around them, gently bopping them with the bamboo stick. make sure incense is lit and burning well.

It's worked for me, twice, so it *MUST* be the right thing to do.
:cool:<HR></BLOCKQUOTE>

I am surprised that this worked for you without a chicken to sacrifice. I guess that different rituals yield different results.

tongue.gif
--PB

Peter Scharman
Sep 21st, 2002, 02:39 AM
Have you tried changing the order of the hookups back to how they used to be? I've had problems in the past hooking up multiple external drives. Switching the order of hookup would do the trick. Termination or firmware issues...who knows!?

minstrel
Oct 28th, 2002, 07:48 PM
Hi, everybody.

I've got my 6100 to boot up the tower with three HD inside. So now I'll just add drives one by one until I find the problem.

Thanks for all your help. I'll keep you posted.

Steve

minstrel
Oct 29th, 2002, 10:24 PM
Hello, again

I'm as confused as ever! I've now got 4 HD the CDROM drive and the HP2x6 CDR-W all in the tower, and it boots like it always used to!

I'm thinking that maybe (just maybe, mind you) my 6100 was feeling insecure, since I stripped out its SIMMs to try in the 7100, so when I reassembled the 6100, it decided to reward my loyalty by behaving properly! ;)

Go figure!

Steve