Quadra 950 Sadmac when CD-ROM drive is connected

[Floofies]

Hey all, I've recently started setting up a Quadra 950 with SCSI2SD. I have encountered an issue where connecting a CD-ROM drive causes the machine to SadMac on boot, sometimes showing a movable mouse cursor for a second beforehand. This occurs regardless if the CD drive is connected internally or externally. I also tried the device shuffle and found it only SadMacs when a CD-ROM drive is connected, regardless of what else is connected to the machine.

The error code is 0000000F 00000001. I tried 2 CD-ROM drives (An AppleCD 300 Plus, and an AppleCD 600i) so I know it's most likely something to do with the Q950 itself.

I have read a little about termination in this model, so I attempted to boot once more with the drive at the end of the internal SCSI cable, with term power on for the drive. I still can not get past the SadMac...

As an aside, there is a mint condition copy of Mac OS 8 in the drive.

Any advice? I am not very experienced with SCSI Macs (In fact this 950 and a few others I obtained recently are my first SCSI Macs ever) so I'm sure I'm likely just missing some tiny detail.

 

[ScutBoy]

Sometimes, things that aren't supposed to work will work. There's a reason it's called "SCSI Voodoo".

Try different SCSI addresses for the drive, termination in place, no termination, terminator in the middle (if you have a pass through terminator), termpower on, termpower off, etc.

I've never seen this hurt anything, and you may come up with a combination that works.

You may also want to check the HD in the 950, and see what it's set at for ID, termination on/off, etc.

 

[Floofies]

The machine SadMacs even when the CD drive is the only attached device, so it's not an ID conflict. I did try changing the ID of the drive though.

Also, I think in a Q950 the internal SCSI bus is terminated on the motherboard, so a single device shouldn't need an additional terminator, but the thing is the drive still causes the crash even on the external bus. The adapter used externally has termination as well, which I've tried both on and off.

The error code indicates it's a "bus error", which can be caused by a bad driver, but it would be the driver on the OS8 disk. I will try my 7.6 disk to see if that works.

 

[Unknown_K]

The last drive on the internal chain NEEDS terminated.

 

[ArmorAlley]

Are you able to boot normally from a floppy?

Does the Sad-Mac occur when trying to boot from the CD-drive?

Does it occur when there is any CD in the CD-drive?

Does it occur when simply when the CD-drive is connected to the Q950?

Does it occur when the CD-drive only receives power from the Q950 (i.e. the SCSI cable is not plugged in)?

When trying to boot externally, is the external CD-drive being powered by the Q950 or externally?

Do any other SCSI devices work on that SCSI-chain?

 

[Floofies]

Well this is interesting. I put in my 7.6 install CD this morning and it booted right up! At first I was a little shocked it might be the mint-condition, purchased-in-original-sleeve OS8 install disk, so I popped that one back in to find it too is now booting normally! What the hell!? Somehow after I let it sit overnight in the cold office (around -1°C, or 29°F) it has unscrewed itself!

This is very, very weird! Could I be looking at a bad SCSI cable? The only other time I've seen intermittent bus errors like this is when there's some bad caps on the board/drive, but the LB has all solid-state caps and both drives are verified working on other machines. I guess now I have 3 machines on my "bad ribbon cables" list...  sigh, I'll have to order an even BIGGER reel of replacement cable now!

ArmorAlley, I did write up some brief answers to your questions, but then I discovered the above. I appreciate your questions though as they provide a good place to start troubleshooting. One question that I still feel is answerable is the PSU related one:

When trying to boot externally, is the external CD-drive being powered by the Q950 or externally?

It didn't matter where the drive got power from, so I ruled out the Q950's PSU pretty quick. If there was a difference we'd know pretty fast to look at that PSU.

 

[Bolle]

I had a SE/30 throw Sad Macs when certain SCSI devices were connected... turned out the term power fuse on the logicboard was blown.

You might want to check that on your 950 as well.

 

[ScutBoy]

Well this is interesting. I put in my 7.6 install CD this morning and it booted right up! At first I was a little shocked it might be the mint-condition, purchased-in-original-sleeve OS8 install disk, so I popped that one back in to find it too is now booting normally! What the hell!?

See? SCSI Voodoo [] ]'>

 

[boitoy1996]

Is it possible the term power fuse is a poly fuse, the kind that blows but goes back together once it cools?