Posted on 30 July 2004
I think the classic compact Macs still look pretty cool, but there was nothing useful to do with my old SE/30 sitting up in the loft. Still, I did want a media server for the living room, and I did want to do a mini-ITX project, and I did want to do some engineering that didn't involve Powerpoint. So, the Mac-ITX was conceived.
Now, I am hardly the first person to put an ITX board in a Mac case, but I was after something a bit different from all the other ones I've seen. Normally the Mac case ends up with lots of ugly mods to it. Inspired by the Stealth SX64 mod I wanted to make it as close to the original Mac as possible - keep the whole look and feel intact. By the way, unlike most ITX mods this one involves lethal high voltages. Don't attempt this unless you really know what you are doing.
The first challenge is what to do with the display. Most Mac ITX mods replace the Mac's black and white CRT with an LCD in the bezel. For me that little curved 9" monitor is a key part of the retro appeal, so I wanted to keep it. My first experiments were to connect the old Mac's analog electronics to the output of my PC. I managed to get a picture but there turns out to be a lot of work to do before getting a good solution this way. The Mac's original monitor circuit really does only support black and white (no greys!) and you would have to design a new CRT driver circuit to make the conversion.
So switch to plan B. Buy a 9" PC monitor off ebay and fix it in to the Mac's case. After a few weeks searching I finally found a likely candidate from a company that produces TV game shows who were selling off some monitors previously used by audience members to cast their votes. Getting it home and ripping the guts out the Mac and the monitor showed that (hooray) the tube is almost exactly the same dimensions as the Mac original, and fits perfectly in the original mounting points without any modification.
Unfortunately I wasn't quite so lucky with the circuit board. The Mac had its analog electronics on a board mounted sideways next to the CRT. The new monitor board won't fit there. I finally managed to squeeze it in above the disk drives and just below the CRT. I also had to turn around the original front-panel controls to face inside the case. Adjustments now have to be done with a very long insulated probe! Fortunately once set right they don't need to be changed. With the CRT and the board in I now had an SE/30 changed in to a black and white monitor.
The ITX board goes where the original Mac's logic board was - in a little space under the Mac's internal sub-frame. This space is wedge-shaped and higher at the front than the back. The Mac designers must have really thought in 3D because all the Mac boards only fit because of the way the heights of the components are distributed. Luck was with me here because the ITX board almost has the same height profile. Strip off the daughter board for the CF and PC-Card slots and it'll just about fit. A bit of cutting needed to give enough room for the heat sinks and IO ports.
For the PSU I wanted to keep the Mac's original mains input and also power the monitor and computer together. I managed to find a 1U server PSU which would fit in the shell of the old Mac PSU (with a bit of sawing). Fitting the optical drive was a labour of love. The aim was to make it fit almost invisibly behind the floppy slot of the Mac. For the drives I used a lap-top HD and a slot-load DVD. With some very careful cutting the Mac's floppy slot was widened to take a CD. The HD and DVD were mounted on a support hacked out of the original Mac's HD bracket. Finally we got time to test the system before fitting it all together.