Mac Plus with Brainstorm accelerator doesn't like system 7

[Patrick]

I have a Mac Plus that has been upgraded with a brainstorm accelerator. Which I understands doubles not just the CPU but the bus also from 8mhz to 16mhz.

I have recapped the board but experienced this .. odd problem before I recapped it.

It boots off of the scsi2sd and floppy emu just fine. But only with system 6. It doesn't like System 7. If I try to install system 7 it will fail during install. If I try with a preinstalled system 7 it will fail during boot with different errrors. Sometimes with -41 and sometimes with an address error.
If I try testing the hard drive with HD SC .. it will spin forever, and then crash if I move the mouse.

the Computer seems to work just fine in system 6.

It does have 4MB of ram and I have tried replacing the ram.

 

[Adam]

Some of these accelerator cards for older compact Macs required custom ROMs on either the Mac or the upgrade card to function. Does your Mac have different ROMs than a stock machine? Or is there a ROM on the accelerator card? My Mac 128 upgrade required different ROMs on the motherboard, and my Radius SE accelerator wouldn’t work with System 7 until I updated the ROMs on it.

 

[Patrick]

The ROM chips are stock. they say apple on them. From what I can find on the internet I don't see any indication that they change out the ROM. That being said, there IS firmware on the board and I updated it from v 2.0 to 2.5 for example did fix the sound. (some sounds had a static aspect to them on version 2.0) So maybe they patch the rom that way?

Maybe its something incompatible with SCSI2SD and I should try to use something more period correct.

 

[Adam]

Is there a ROM newer than 2.5? Maybe it just doesn’t work with System 7. I have some Nubus cards that never got a driver update to work with system 7, and some that will work but only if you update the ROM.

 

[Patrick]

The software I found at Macintosh garden only went up to 2.5. I'm pretty sure thats the last one. There is a lowendmac review from 2000-ish that had them running 7.5.

@aradiogurl I noticed on your twitter feed you had a Mac plus with brainstorm . Did you try running it with system 7 if so .. did it work?

I'm trying to figure out if the problem is because of the accelerator or something else in the computer is wrong.

 

[aradiogurl]

The software I found at Macintosh garden only went up to 2.5. I'm pretty sure thats the last one. There is a lowendmac review from 2000-ish that had them running 7.5.

@aradiogurl I noticed on your twitter feed you had a Mac plus with brainstorm . Did you try running it with system 7 if so .. did it work?

I'm trying to figure out if the problem is because of the accelerator or something else in the computer is wrong.

I only picked it up last week and I think I've only tested it with System 6. This gives me a good excuse to pull out my System 7 Mac Plus boot drive. I'll see about testing it today or tomorrow and let you know my results.

 

[aradiogurl]

I only picked it up last week and I think I've only tested it with System 6. This gives me a good excuse to pull out my System 7 Mac Plus boot drive. I'll see about testing it today or tomorrow and let you know my results.

I had some extra time during lunch so I pulled out my System 7.1 boot drive and hooked it up. It booted without complaint. I updated my firmware from 2.0 to 2.5 and continued testing. I installed TattleTech and Speedometer 4.02. TattleTech still reports a 8MHz 68000, but the benchmarks proved it was actually running at 16MHz.


I know you replaced the RAM already, do you happen to know the speed of the RAM? From my research the brainstorm accelerator is very picky about RAM speeds. System 7 is RAM hog compared to 6 which might make it more likely to experience RAM issues. I'm running 80ns RAM in my Plus.

 

[Patrick]

I'm not sure what speed the ram was in the plus. but I replaced it with 80ns ram and had no impact. (it worked the same)

As far as the tests I had the exact same experience you had. it reports as a 8Mhz 68000 but benchmarks has it run at 16Mhz. (interesting!)

I'm not sure how much software you tried when running on 2.0 firmware. But I noticed the sound could be scratchy. Like Klondike has this little doodle at the start. Upgrading the firmware from 2.0 to 2.5 fixed the sound in this case.

Thanks for testing I'm trying to narrow down the possible problems. it sounds like its not the Brainstorm accelerator. At least I know on paper it should work with system 7. I know lowendmac has a review from like 2000 or so .. where they did performance tests on the Brainstorm using 7.5.3

are you using SCSI2SD ?
I wonder if its either my scsi2sd or maybe my partitions are too big. or my settings are not correct. (I know the plus can be picky)
I WAS using Lido to partition. but I heard later that Lido doesn't work well with the plus. So I switched to Apple's HD SC software.

or perhaps something is wrong on the logic board that makes it a little bit unstable.

I do have a stock Plus where it works fine with system 7 and scsi2sd. so ¯\_(ツ)_/¯

 

[aradiogurl]

The little I played with it I didn't notice the sound issues, but my hearing isn't great, I'm sure they were there.

I am using SCSI2SD, v5.1 I believe. I installed it into an old external SCSI case and power it from a power brick. In the config I set Enable Unit Attention to off, SCSI Selection Delay to 0, and Respond to short SCSI selection pulses to on.
I setup SCSI device 0 to be just under 2GB in size and used the patched Apple HD SC Setup to format it. I originally setup this drive using a stock MacPlus w/4MB of RAM and the System 7 images that came with my Floppy Emu.

There could be something with the motherboard, but it would most likely eventually show under System 6.

One random thought, have you checked the voltages from the analog board? The accelerator probably pulls a little more current than a stock Plus. If the voltage is just slightly too low that could cause some odd issues, although I would expect to see the issue under 6 also.

Definitely an interesting issue.

 

[Patrick]

Do you mean checking voltages throught he floppy port? If so i did. I should also mentioned i recapped the analog board... its totally possible i didn't do it right. Hopefully i left it better then when i started with.
I *THINK * i also tried it on other analog boards.(like a 512k i'm working on) I could try swapping things around again just to see if the problem is on a specific analog board or something.

I'm concerned that i can't even seem to format the drive using HD SC. and the computer resets once i move the mouse. (if i don't move the mouse it will just spin forever) I'm wondering if that is pointing to the real problem? ... whatever it is.
If so, this might be beyond my skill to troubleshoot.


i checked my scsi2sd and its the same config as you described.

 

[aradiogurl]

Yes, through the floppy port is one of the safest ways to check voltages. I always check DC and look for AC leakage, then I'll monitor startup voltages, verify they don't spike too high, then watch it while using the system. The only time I've seen any of my Plusses restart is when there are power supply issues, but my experience is limited to about a half dozen Plusses.

I've only done partial recaps of my Plus analog boards, usually just RIFAs, sometimes a couple other electrolytic, eliminating AC leakage.

When I'm formatting a SCSI2SD using HD SC it's slow, I'll start the format then go do chores for an hour. I've not seen the issue where moving the mouse causes a restart, that's definitely a major issue and I would believe it is related.

Just to be certain, I would test it with another analog board.

Beyond that, I would imagine it's time to start checking the board using a logic probe or oscilloscope, verify the controllers are responding properly and not getting stuck. This is sometime I"m still re-learning how to do, it's been close to 20 years since I've used an oscilloscope for anything but troubleshooting antique radios.

 

[Patrick]

When I tested the voltages before, I only did it at the flashing ?.

so this time, I did it while booting via 6.0.8 floppy. and trying to boot a system 7.0 scsi2sd card.

the 5 volt stayed around 5.088 or so pretty steady.
the 12 volt one around 12.36
are these good numbers?

If I run HD SC and run a test it will sit and spin. if I move the mouse it will crash in some form. sometimes just beep and reboot. other times it crashed and the screen went white with like vertical lines.

I think you are right that I'll need a logic probe or an oscilloscope. that might be beyond my current skill set though. I've seen YouTubers use them sometimes. but I'm still confused by oscilloscope. I'm guessing it will hopefully point to some chip that needs replacement ? maybe a chip is getting too warm ?

I think for now I might set this on a shelf with a note with what I found. Maybe in the future I'll have more skills that I can troubleshoot this more. I have plenty of other projects to keep me busy for now. Thanks for the help and testing things on yours! it makes it easier to test things when you have more then 1 thing.

EDIT: I forgot to mention. When I've replaced the caps on the analog board, even caps that look ok, they sometimes have a tiny little leak at the bottom. I've decided I'm not good enough to know if a cap is good or bad till I take teh cap off. and at that point, I might as well replace it. Maybe when I have more XP I can tell better later. ¯\_(ツ)_/¯

 

[aradiogurl]

Those voltage numbers look healthy.

A chip could be overheating, when I'm diagnosing a system with weird issues I often check ICs with my fingers, some use an IR thermometer.

I was in the same boat a few years ago and had to shelve projects that were above my level. I resumed work on some of them this past year, finished a few, making progress on others, couple are probably going to stay shelved for another year or three.

I've seen similar issues with caps starting to leak out the bottom, every Classic and Classic II analog board I've touched has suffered leakage, even working ones are usually boarder-line failing. If I'm recapping stuff for others or for long term use I just replace all the caps. I also have tools that let me check capacitors in-circuit. They're not 100% effective, but was helpful when I bought a pile of Mac Plusses and wanted to get them all working without needing to rebuild them.

Happy to have helped. Not many of us out there with working systems, it takes a community to help keep them running