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Judging by the troubleshooting info around here at 68kMLA, that's definitely a logic board issue!  Tongue-in-cheek, check the address multiplexers, check the ROM, try with different RAM or different amounts of RAM, etc.

Nice! What did your plan for the PSU issues turn out to be?  Did you end up fixing your existing PSU, get a replacement one, or some other magic didn't require changes there? Also, did you hear a reasonably sane startup chime?

Also, I see I0 is labeled as Not Connected (NC) but it is still referenced in the  of the OE equations !FCLK.oe, !B6.oe, and !IPL0.oe equations. Simplifying !B6.oe by hand looks like this. !B6.oe = !WRDATA & !ENBL1 & !PA4 & !CLK & !PA3 & !RTxCB & !OE...

A bit of a common sense check on *IPL0 on the GLU, since we also have the BBU connecting to *IPL0 via a +5V pull-up resistor, this value should only ever be high-impedance or GND, correct?  If so, that common sense can certainly take a chunk out of the complexity of the OE equations.  That just...

Yes, yes, loaded up with 4 MB of RAM. Relating to the idea of a replacement BBU, unfortunately it's almost, not, possible.  We'd need like 74 I/O pins but best I'm seeing is FPGAs with 72 I/O in the 84-PLCC layout.  (The obsolete products with 74 I/O are there to taunt me.)  But hey, if we...

I'd estimate that to be about 380 floppy disks.  Great find. Any driver disks are definitely a plus.  There's definitely some old hardware floating around that is unusable because the drivers are missing, like the Megascreen 3 video card in my Macintosh SE.

So close... I have to say I have high hopes about this.  Relating to the previous discussion about the BBU pinout, it looks like it's all correct on the actual board design, Sprint Layout's misclassification of MBRAM and ROW2 was due to the fact that these are connected to pull-up resistors. ...

Wow, really?  So Uniserver just copied the BOMARC schematics and put a price tag on them? I do have to agree, though, there seems to be a heck lot of copying for the schematics but not very many folks putting effort to improve quality on them, so I guess I shouldn't be too surprised if this is...

I've noticed the note #4 at page 1 erroneously says "RDB" instead of "ADB". Now that I'm getting more into redrawing the Macintosh SE MLB schematics, I'm also looking to the redrawn SE/30 MLB schematics for reference.  Though the original SE/30 scans are not nearly as illegible or as incomplete...

Judging from the 1/3 in the bottom right corner and the tiny text above it that appears to say "SHT" (sheet) in scans of other pages, I'd assume page 3 of the main logic board schematic is also missing, unless you've turned up something for that.  At least we have some hints about which...

So I decided to split up modernizing the Macintosh SE main logic board schematics into two stages.  The first stage is for my own proof that I can actually read anything meaningful off of the original scans: trace over vector graphics and typed text on the original schematic image.  It's almost...

Looking at the fuzzy Macintosh SE schematic right now, a first try at a grayscale conversion and gamma-adjusted image rescaling seems to make at least some parts easier to read, albeit at reduced resolution.  I'm looking to try my hand at redrawing this if I think I can see sufficient detail...

+1, I would also agree.  I'm guessing probably the main reason for doing otherwise would be as part of the first stage of Tindie sales to recoup the costs.  But otherwise, for the publicly available designs, definitely I would prefer 1:1 so that we can emulate the good old feeling of...

Wow, I feel like I've come late to seeing this development.  1/2 what I was wishing would happen. The other half, modern schematics for the Macintosh SE.  Well, I've seen what @elemenoh has done for the SE/30 schematics and these two separate projects together really makes me want to go and do...

Oh wow!  Not sure why I had trouble linking across the forum in a durable means before, but in any case looks like 68kMLA now has a reliable means to do so.  This is what I found chasing around.

Ah, yes, link hacking magic, the working link has been restored.  Yes, it's an SE/30 instead of an SE.  But I see there is SE/30 on your exterior case from the photo.  (No mention of checkerboard here actually, but helpful advice.)...

Elsewhere on the forum I believe mention of a similar problem with checkboard pattern pointed to bad address multiplexers.  You could try replacing the address multiplexers and see if that works, but I'd defer to looking at that forum post first.  Here is the link to the forum post I saved on my...

Nice!  If I don't get any more info about anyone who's started a PCB layout, I might create a simple pull request so that we can get something simple started that would at least be helpful for an interactive BOM and recapping projects.  But, before that, probably the first pull request I may...

Wow, really nice work @elemenoh, this is just what I was hoping to see happen sometime. Definitely I'd like to see these schematics make their way into a better information repository than Google Drive, like the 68kMLA wiki, etc.  I'd offer that probably the best way to go about...

Yeah, I've made that Thingiverse model using SLA printing as-a-service from dirtypcbs.com.  It's pretty cheap there, and the buttons appears to work well, I've taken it out and put it back in a few times and had no trouble other than it is a bit stiffer than the original, so it seems, but...