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Running a MacSE/30 without an analog board?

Tom2112

Well-known member
I was watching a YouTube video by Adrian Black of Adrian's Digital Basement. In it he showed a nifty tool called the RGBtoHDMI Video Interface, and he grabbed the video signals right off the logic-board-to-analog-board connection and wired them into this RGBtoHDMI device which output a pixel perfect display to his HDMI monitor. (links to the video and hardware below)

That made me think... I wonder what other signals pass through that connector (J12)? So I dug up this nice pinout diagram:
SE-30 Logic Board Pinouts and Caps.png

According to that, the only things going through J12 are power, ground, and video.

So that made me think... since the analog board's flyback transformers are very hard to repair/replace, a person with a bad one could remove the analog board and the CRT and replace them with a modern power supply, the RGBtoHDMI device, and a small HDMI LCD panel...

The hard part would be finding a modern PSU that supplies the negative 5 volt rail. But maybe you could just use the existing SE/30 PSU...

I suppose a really creative person could replace the hard drive with a SCSI2SD, remove the floppy, stand the logic board up with the PSU below it, and make a very shallow backed SE/30 using just the front bezel and a 3D printed rear case... making it only 4 or so inches deep...

Am I crazy, or does this actually sound like it would work?

Links:
Adrian's RGBtoHMDI for Mac video:
https://youtu.be/pvjsXbz1xlk

RGBtoHDMI adapter:
https://retrohackshack.com/2021/07/20/now-selling-the-rgbtohdmi-adaptor/
 

bdurbrow

Well-known member
I already have a board layout that takes an ATX power supply as input, and generates the required -5v rail, and connects to the SE & SE/30 power connector. It also has a standard 0.100 header with the video signals on it, so you can connect it to a display solution (like that RGBtoHDMI).

It's waiting on a few other PCBs to be done before I send them all off in a batch to be manufactured.
 

aeberbach

Well-known member
I'm working on this. Getting a replacement power supply is actually easy, Mean Well make two or three modules providing 12V, 5V and -12V, then the -5V rail is just an additional 7905 regulator. So now I have a replacement power supply board that mounts one of these modules and replaces the analog board to the side of the Mac. It has a power inlet and switch matching the original in the right place to look like it's unmodified when the case is closed. It even has a rotary encoder in place of the old brightness control.

I have a LCD module and have made a board that generates the various voltages the panel needs. All the 3D printing is done (PSU is in gray, LCD mount is in orange, pic below), the LCD's voltage driver board is mounted neatly behind it. At this stage I am powering up the LCD with FPGA control and working on writing the HDL to convert the Mac video to LVDS to drive the panel. I've had it working with an intermediate converter board but I want to do it all in one eventually, one board containing a FPGA and all the LCD power supply stuff. Should be neat.

You can do it now with a bunch off boards all wired together of course. The aim of what I am doing is to make something Mac-like, meaning no intermediate menus, no control boards hanging out the back, no linux boot sequences, no wires hanging everywhere. Just a Mac that looks like it always did, turns on with one switch, and just works.

Pic of power supply module in place:
IMG_0141.jpeg
 

cheesestraws

Well-known member
Yes, running SE and SE/30 LBs without a logic board is absolutely possible, and in fact pretty electrically trivial. The slight wrinkle is doing something useful with the video signal, and, if you want to make the machine itself usable, rather than just do this for testing, making it in any way neat.

For testing and working on LBs outside of cases, I built a bench PSU out of an ATX PSU and added a -5 V rail with a DC/DC converter. This has tails for different kinds of logic boards, which are just cables from a set of banana plugs to the right Molexish connector, I've also laid out a PCB for the video converter on waveguide.se which should (hopefully) work with the OSSC I already have on the workbench for testing older machines with. We'll see about that when it arrives.

You can do it now with a bunch off boards all wired together of course. The aim of what I am doing is to make something Mac-like, meaning no intermediate menus, no control boards hanging out the back, no linux boot sequences, no wires hanging everywhere. Just a Mac that looks like it always did, turns on with one switch, and just works.

The more I see of this project the more excited I get about it. This is good stuff.
 

Tom2112

Well-known member
Wow, Aerberbach, that's really something! Nice work!

I'd like to see a board that replaces the analog board (same connector for the PSU and logic board so you could continue to use the original PSU if you wanted) that has an HDMI or VGA out. That would allow the hobbyist who can't replace a bad flyback to easily swap out their bad analog board and still source their own display solution. Even better if it had two power connectors, one standard MacSE PSU, and one standard ATX with something built-in to create the required negative 5v rail. That way a person could keep an old PSU or use a modern one. But, that's big talk for someone who doesn't have the foggiest idea how to design circuit boards. Some days I wish I had taken some electrical engineering classes. LOL
 

max1zzz

Well-known member
I have used a RGB2HDMI to successfully run a plus board off a bench supply outside the chassis. I see no reason this would not work on a SE/30 board (In fact I seem to remember reading somewhere that the Plus and SE's video signals are actually compatible)

I have been meaning to make a compact bench test set-up using a RGB2GHDMI and a ATX PSU to allow me to work on compact boards without having a chassis on my desk, Just haven't had the time to set it up yet
 

aeberbach

Well-known member
I split the analog board/power supply part from the main project and I have published it now - https://github.com/aeberbach/MacSE-SE30-analog-replacement

Have fun and I'm keen to know what you use it for!

If you're in Australia and you want a PCB, let me know. If you're elsewhere then getting it shipped might be the most expensive part and JLCPCB can send you 5 for the same cost I can send you one, maybe even cheaper.
 

chillin

Well-known member
This is an awesome idea. Pleased to hear it is possible. I always wanted to run an SE/30 logic board headless inside an old Apple external scsi drive case. This would need a tiny PSU, and I'm not sure an ethernet PDS could fit. Unfortunately, those Apple external scsi drives have gotten rare, and the prices for these vintage pieces skyrocketed, so even if such a tiny PSU existed and the network adapter fit, gutting one of those Apple scsi drives to make a headless SE/30 has become a very bad idea, economically speaking.
 

Trash80toHP_Mini

NIGHT STALKER
Yes, running SE and SE/30 LBs without a logic board is absolutely possible, and in fact pretty electrically trivial. The slight wrinkle is doing something useful with the video signal, and, if you want to make the machine itself usable, rather than just do this for testing, making it in any way neat.
You really shouldn't need to try doing anything useful with the SE/30's crappy video system.

Unlike the SE, the SE/30 is of the Macintosh II Slot Manager architecture. Just yank its "Video ROM."In all but name, it's the Declaration ROM for onboard video and without it, suddenly the SE/30 has no video system or video buffer to fill. Use any PDS Video card for your external display, no problem?

/tangent alert?
It's likely impossible, but I'd like to see if the remaining non-PSU parts of the A/B can be redesigned/replaced with a unit that can torque the flyback into supporting a 640x480 feed to the GS neckboard in 8bit at that resolution on the CRT. Re-creating the well documented Macintosh II Frame Buffer (Toby) NuBus Card as a PDS card for the SE/30 should be fairly easily done, all things considered. The question is running the kluge without blowing the flyback.
 

Trash80toHP_Mini

NIGHT STALKER
Good point, I do have an embarrassment of riches on hand. I need to consider passing some of them on at some point.

The constrained case approach honors the spirit of the Computer Shopper series on CatMac building, precursor to the Hackintosh title/movement. I'll suggest reclaiming the CatMac term here as "Hacintosh" has been usurped in more recent years for a far less deserving project than the traditional, hard core hardware hacking project.

I will note however, that anyone considering this SE/30 Hackintosh build should be on the lookout for the relatively inexpensive Radius Color Pivot II/IIsi while prices are still within reach. Unlike other cards it can drive any decent multisync display/current LCD. It also acts as a right angle adapter for a second 030 PDS card within the constraints of the likes of the ZFP HDD case in consideration. ;)

edit: the links in that thread are broken. Looks like you'll need to do advanced search for title/author to find them.
 
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davewongillies

Well-known member
Hi there,

I ended up doing pretty much what was discussed in this thread but with a Macintosh Classic II. The logic board is powered by an ATX4VC paired with picopsu, and video out is handled by the RGBtoHDMI with the TTL board. Besides the BlueSCSI I've got no HDD or FDD connected so its powered just off the 5V rail of the ATX4VC. For the case I went with a Hammond RM2095M project case as it came in an reasonably appropriate shade of beige. On the display side of things I've got it hooked up to a repurposed iPad 2 display with one of those lcd driver boards from Aliexpress.

1707860727778.png
 
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davewongillies

Well-known member
Can you post pics of video connection etc?

On the logic board there's the 14 pin molex connector J11 which has vsync, hsync & video out. I purchased a 14 pin ATX cable off Amazon and used it for connecting everything up (this pin extraction tool came in handy for pulling out and rearranging the cables). The pin outs for J11 can be found here (its the same for both the Classic & Classic II).

1708129077456.png

From J11 I'm running cables from pins 4, 5, 6 & one of the grounds to a DB-9 cable with screw terminals that I also got from Amazon

1708129243045.png

Then that plugs into the RGBtoHDMI (purchased from here).

1708129365732.png

This post from Tinkerdifferent was useful in figuring out how to connect it all up
 

dcr

Well-known member
I'm glad this thread came back to life as I hadn't seen it before.

I have an extra Mac Plus logic board with no analog board or CRT or anything else and it would be nice to be able to build something with it that could use a modern display.
 
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