Color Classic Mystic Bomb Bus error problems booting

[Thayer]

Hi all wondering if someone can help as not sure if there is something simple I am missing. I have a perfectly working Color Classic with Mystic upgrade. It has been recapped, new PRAM battery and never had any leaky caps, corrosion on the logic board or anything like that. Even though the HDD works fine I wanted to replace it with an internal BlueSCSI v2 as I have used the external one with no issues.

After removing stock HDD and putting the internal Blue SCSI in when I boot I get a happy Mac, Welcome to Macintosh and then a few seconds later a bomb! bus error. I have confirmed the image on the SD card is bootable 7.5.3 and the board has termination set to ON. After thinking it was my BlueSCSI or the SD card causing the problem I removed it completely and tried to boot with an external CD rom or floppies (I have bootable media for both) . Same thing happens with these - I get a happy Mac, Welcome to Macintosh and then a few seconds later a bomb! bus error. The crazy thing is I put the HDD back in and the system boots fine.

Am I missing something? To do with termination maybe? My external CD rom is terminated properly and when I try to boot off floppies the CD Rom is not even pugged into the external SCSI port. Is it possible to boot from floppy with no HDD or external drive installed?

Any help is appreciated.

 

[pizzigri]

Strange, have you checked termination power?
as I recall it is possible to boot from a floppy - that was how you installed the os on the CC. Not sure what you want to do with it tho.

 

[mikes-macs]

Since it's clearly fine with the HDD I think It's a question best handled by the people who support Blue SCSI.

 

[Thayer]

Strange, have you checked termination power?

Not sure how to do that is there a specific way? Also really why want to boot from Floppy or CD is just to test it to rule out the fact that the BlueSCSI isn't causing the issue.

 

[Thayer]

Since it's clearly fine with the HDD I think It's a question best handled by the people who support Blue SCSI.

That was the first thing I thought of but if I unplug the blueSCSI completely and try to boot from floppy or CD I get the same bus error and no boot so it doesn't seem to be the blueSCSI as the culprit.

 

[mikes-macs]

My apologies I misunderstood. If the bus error occurs without the blue SCSI then perhaps it's something related to the recap or the memory that is installed. I've had this issues and found it was a bad memory stick. Just to be sure though is the system folder that you use to boot the Mac with an actual system for that Mac, fresh install? Was the HDD formatted with that same Mac using the correct utility for that Mac?

 

[Thayer]

My apologies I misunderstood. If the bus error occurs without the blue SCSI then perhaps it's something related to the recap or the memory that is installed. I've had this issues and found it was a bad memory stick. Just to be sure though is the system folder that you use to boot the Mac with an actual system for that Mac, fresh install? Was the HDD formatted with that same Mac using the correct utility for that Mac?

I was thinking might be related to memory but then would I not have the issue once the original HDD is plugged in? If I put that back in the machine boots fine - it is only when I remove the HDD and try to boot the machine from floppies, CD or the BlueSCSI that I receive the error.

As far as media I am using original floppies that are tested and working and install system 7.5.3. I have tried some other bootable floppies (disk tooks etc) with same result. I have tried different images on the BlueSCSI of 7.5.3 and have verified on another machine it is a valid bootable image (I created it with infinite mac.org). The CD is not original it is a burned copy of the Apple Legacy Recovery.

I just don't understand why when the HDD is unplugged why I can just boot via other means - nothing seems to work.

 

[mikes-macs]

I think you'll end up getting the answer from someone here who know more about it. Those were the few things that I knew of to check. It's Memorial Day Weekend so I'm assuming the usual experts at this stuff will chime in and help you solve it later on. I never recapped anything so I don't know. Could be something wrong with the board more advanced than I can help you with. Sometimes it's just a bad connection on specific components or solder somewhere there shouldn't be.

 

[pizzigri]

Are you trying to boot the CC from the external port without having a drive inside? Or without anything in the machine? the internal cable, since it’s always connected, needs to be always properly terminated- use i.e. another hd. some machines are more sensitive to this than others…. Just a thought.

 

[Thayer]

Are you trying to boot the CC from the external port without having a drive inside? Or without anything in the machine? the internal cable, since it’s always connected, needs to be always properly terminated- use i.e. another hd. some machines are more sensitive to this than others…. Just a thought.

I did think of that but did not think it was an issue as the BlueSCSI was connected (confirmed it had power as the led light on and the jumper from termination is set to 'ON').

I am going to try another HDD as I think I have one around here - even if just to provide termination.

Also something I did not think of - install the original HDD which I know will boot the system but THEN try to boot off floppies or CD and see what happens.

 

[MacKilRoy]

Your Mystic-upgraded Color Classic, is it running with a resistor mod that makes screen resolution the default CC one?

I believe you have to use a modified system folder or enabler when you do that. Which might be what's on your internal hard drive, but not on the other installers you're trying.

 

[Thayer]

Your Mystic-upgraded Color Classic, is it running with a resistor mod that makes screen resolution the default CC one?

I believe you have to use a modified system folder or enabler when you do that. Which might be what's on your internal hard drive, but not on the other installers you're trying.

Ahh maybe - the thing is I have only owned this for about 8 years or so - I'm not the original owner. How exactly can I tell if this mod was done as I'm not familiar with that.

 

[MacKilRoy]

When booted into MAC OS, what screen resolution is available to you in the monitors control panel?

 

[Thayer]

When booted into MAC OS, what screen resolution is available to you in the monitors control panel?

I'll have to put the HDD back into the system and boot and I'll check. What resolutions should I check for? I'm assuming there will be options that would not normally be there?

If it is the case it has the resistor mod, what differences do I have to make to the OS install?

I'll be proactive and do some research on it but was thinking of it's something simple.

 

[Thayer]

HI all I wanted to update this in case anyone has a similar issue in future. I installed my original HDD and as expected the machine booted right up.

I checked and I do not have the res mod (as asked above) - I only had the option for the normal CC resolutions. I then tried with the HDD attached to boot from floppy or CD and received the same bomb bus error.

Now I knew it had nothing to do with termination - it had to be a software problem. I remember reading this old thread:

MicroMac Mystic Upgrade - Specifically the part on "Are there any additional requirements for installing Mac OS 7.5".

I have the 68040 processor with 80/40MHz on my LC575 board so it seemed to be a gestalt problem according to this. I guess this is why I am unable to boot from floppy or CD. There are ways to fix it but no need since I was able to copy the contents from my original HDD to an external BlueSCSI and that to my internal BlueSCSI. Once the internal HDD was removed again and the internal BlueSCSI installed it works!

Thanks everyone for the help!