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Nubus slot problems


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How do you diagnose NUBUS slot problems on a IIci?  Are they repairable?

 

Here is the situation:  IIci, hard drive was replaced with a SCSI2SD.  We have a special card in the NUBUS slot which communicates with a motion control board which is attached externally.  From everything I can see, the software is installed correctly on the IIci, and it starts up as expected.  The problems start when the IIci starts communicating with motion control board.  It appears to be sending the wrong instructions to the motion control board and as a result, the large machine it controls is exhibiting some odd behavior.  I am using the same SCSI2SD setup on 2 IIsi that are attached to 2 other machines that are the same model as the one with the IIci in it, without issue.

 

Due to the bizarre behavior, we swapped the SCSI2SD IIci for an older one we have for back up with an ancient HDD in it.  Same software, same NUBUS card, same motion board.  The problems with the large machine disappeared.  The only significant difference is the SCSI2SD. As I am running those two other machines on a SCSI2SD without issues, I am reluctant to focus on the SCSI2SD as the problem, especially since it boots the way it is supposed to, and starts up the software the way it is supposed to.  

 

Could it possibly be the NUBUS slot?  Considering that the boards are the same and the strange behavior ceases to exist when installed and attached to another IIci, I thought it would be worth asking how to determine if that is indeed the problem, and how to tell what can be done to fix it.

 

 

Edited by Iamanamma
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WAG here is that there may be one iffy trace or maybe a cold solder joint on the connector that's producing odd (intermittent?) behavior? If not, checking that one slot against the others would be my first step in debugging. ISTR there being a utility like the NuBus/PDS function in TattleTech which may have some testing capability?

 

Pulled out the manual for TECHTOOL PRO 3.0.6 and while it doesn't have specific slot testing, it has the ability to run a suite of tests for a Video Card in PDS, NuBus or PCI slots that may give you a clue as to the location of the problem. The components test checks the likes of VIA which controls timing for NuBus, etc. and is mentioned in the Video test section.

 

Happy hunting!

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9 hours ago, Iamanamma said:

Could it possibly be the NUBUS slot?  Considering that the boards are the same and the strange behavior ceases to exist when installed and attached to another IIci, I thought it would be worth asking how to determine if that is indeed the problem, and how to tell what can be done to fix it. 

There's a useful tool on one of the Apple Developer CDs called "Slots" (I think) that will tell you in detail what the computer sees in each slot.  What I've done in the past is to compare the output of that between computers to nail down whether things are card problems or slot problems.  I'm happy to wrap up the contents of my "Nubus" folder on my recovery/troubleshooting partition for you, if you would like to have a look.

 

edit: though if the card seems to be sending the wrong commands to the machine, this almost feels like it might be an electrical problem, depending on how that communication works.  Is everything grounded that ought to be?

Edited by cheesestraws
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9 hours ago, cheesestraws said:

though if the card seems to be sending the wrong commands to the machine, this almost feels like it might be an electrical problem, depending on how that communication works.  Is everything grounded that ought to be?

The card only sends the wrong commands when it is in that particular IIci.  Moving the card to another IIci totally eradicated the problem. 

 

 

9 hours ago, cheesestraws said:

There's a useful tool on one of the Apple Developer CDs called "Slots" (I think) that will tell you in detail what the computer sees in each slot.  What I've done in the past is to compare the output of that between computers to nail down whether things are card problems or slot problems. 

I do not have any of the Apple Developer CDs, unfortunately.  How do you go about using a CD to diagnose a IIci?  I can't run this IIci with an OS higher than 7.1, and the only External CD-ROM I have is USB.  

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8 hours ago, Iamanamma said:

I do not have any of the Apple Developer CDs, unfortunately.  How do you go about using a CD to diagnose a IIci?  I can't run this IIci with an OS higher than 7.1, and the only External CD-ROM I have is USB.   

I'll send you the tool.  It's not the CD that's important, it's just an application on the CD :-).  It just provides quite a lot more information than say system profiler does.  I'm still in work now so I can't dig stuff out for another half an hour or so; if I don't post it by tomorrow, remind me.

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11 hours ago, Franklinstein said:

Has the problem machine been recapped? You could be having power stability problems since there's going to be a pretty noticeable difference between the power draw of a typical HD and a SCSI2SD. Does the SCSI2SD even use the 12v line?

Yes, we have had all of our II series Macs recapped.  If the 12v line is the one with the molex cable power cable, than yes, the SCSI2SD is using the 12 v line.  I can't get it to work correctly with out it, although some folks have reported that the SCSI cable delivers enough juice to power the card.  I have not found that to be applicable to my machines.  They all need a molex cable with an adapter plugged into the socket on the board.

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  • 2 weeks later...
On 10/8/2020 at 11:53 PM, Franklinstein said:

That Molex cable supplies one 5v, one 12v, and two ground lines. The SCSI2SD only uses the 5v line while ignoring the 12v and without a load on it the 12v line may have some hiccups that could adversely affect things. Just a thought.

I think I understand what you are telling me.   It just makes me curious why the IIsi's, having identical set-ups, are chugging along like champs.  I am only having issues with the IIci.  If I understand correctly, a IIsi is pretty much a scaled down IIci.  If there is more to it, I would love to know the hows and whys.

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