jmacz Mac IIfx Project

[Chuckdubuque]

Those of us with 3d printer’s would love that model too.

 

[Chuckdubuque]

Ran into a problem today. Booting is working perfectly after the fixes detailed earlier. But post boot (after reaching the Finder), I was getting random crashes and lock ups. As I wrote down the pattern (when it happens), it seems it's only during disk IO. I'm using a ZuluSCSI Mini connected via the external SCSI port, no internal SCSI device.

I tried swapping memory, video cards, etc to rule them all out and none had an effect on the issue.

I then removed the ZuluSCSI Mini and connected a ZuluSCSI 1.1 via the internal SCSI connector and used the same exact disk image I was using on the external ZuluSCSI Mini. No problems. Kept trying to repro but could not, even slamming it with disk operations.

The ZuluSCSI Mini has permanently enabled termination, but not sure how this relates to the need for a special IIfx terminator.

I then tried providing auxiliary power to the ZuluSCSI Mini (via USB) and that seems to work and stabilized things. For the internal ZuluSCSI, I had used aux power as well.

EDIT: spoke too soon, still getting the issue even with aux power. Just with external devices though.

Did you try formatting the SD card with SD Card Formatter. That has solved a lot of these problems for me.

 

[jmacz]

Those of us with 3d printer’s would love that model too.

Of course. I was planning to post it here publicly.

Did you try formatting the SD card with SD Card Formatter. That has solved a lot of these problems for me.

What is SD Card Formatter? The card was formatted Fat32. And was working fine in all other Macs except this one. But as I mentioned more recently, I can no longer repro, which doesn’t mean it’s fixe, but rather I will have to debug when it shows up again.

 

[Chuckdubuque]

Of course. I was planning to post it here publicly.



What is SD Card Formatter? The card was formatted Fat32. And was working fine in all other Macs except this one. But as I mentioned more recently, I can no longer repro, which doesn’t mean it’s fixe, but rather I will have to debug when it shows up again.

Cool!

Sdcard formatter is a tool that is supposed to better align a raw format to the peculiarities of an SD card. https://www.sdcard.org/downloads/formatter/

 

[jmacz]

Here's the model for the modified cover for the MeowToast. Let me know if it works for you.

 

[macuserman]

I can share the model when I get home tonight. Or are you saying you don’t have access to a 3D printer even if I share the model?

I don't have a 3d printer, but I realized the macbatt is really not that expensive so I just ordered a bunch more of those instead, I'll give the meowtoast away to someone or something not worth going to the extra trouble. I do appreciate it though!

 

[micheledipaola]

Finished putting the IIfx back together today.

I have dual CR2032 batteries installed, using two MeowToast's and a custom cover I made that holds the MeowToast better. Without the little support, the MeowToast keeps moving around so this locks it in.

View attachment 61438

I tried with a similar button battery holder, the one keeping batteries horizontally /parallel to the logic board, and my IIfx would not power up, while oldstyle batteries worked. I thought it was because button batteries in fact provide a little less power, but your experience seems to prove me wrong... so now I wonder how I could make that work. It doesnt seems to move, so maybe you have some advices to share? Thanks in advance

 

[jmacz]

For my IIfx, it's still on the stock power supply (I have not yet converted it to ATX and don't plan to until it fails -- and I'm told these IIfx power supplies are much more robust than the Mac II power supplies). I'm using two CR2032 batteries which provide 3V each. The stock 1/2 AA batteries provide 3.6V each so they do provide more power. But my IIfx starts just fine with the CR2032 batteries.

I just went and checked what voltage I'm getting from the two CR2032s. With the power unplugged to the IIfx power supply, I placed my multimeter probes on pin 15 on the PSU<->Motherboard connector and ground (one of the other ground pins) and then pressed the power button to see how much is being sent to the PFW pin 15 to signal the power supply to start. I saw around 4.3V to 4.4V. So it's not using all of the power the CR2032s have so I would think it should be fine (and on my system, it works fine).

I'm curious what you're seeing on pin 15 if you do the same experiment with the normal 1/2 AA batteries and your CR2032s.

 

[jmacz]

BTW, I was just checking Guide to Macintosh Family Hardware from Apple (second edition which includes the IIfx) and found this in the power supply section for the II/IIx/IIfx:



And here's Figure 6-7:



So it looks like Apple's expecting only 3V per battery and note that based on the text blurb above, only 3V is actually necessary to signal to the power supply to turn on. So two CR2032 coin batteries should clearly be enough.

Again, I think it would be good to see what you get measuring the voltage on pin 15 (PFW) when you press the power button and you have the coin batteries in place. That might help at least figure out the problem. If you have the proper voltage there, perhaps there's something going on with the power supply. If there's not enough voltage there, something must be going on with the power-on circuit.

Here's the pin reference for the PSU connector in case you need it: