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I was able to locate the resource that was most helpful to figuring out where to look for problems: https://www.downtowndougbrown.com/2015/03/explanation-of-the-macintosh-iiiix-power-onoff-circuit/ and then here's the preterhuman page...

Hey folks, doing some thread necromancy as I've gotten the IIcx to chime, no clicking, with an Astec AA16870! At some point, I had a long, hard think about what was going on with this board because someone, somewhere, said that the power circuit for the IIci was well understood... and at some...

Having finally had a moment to poke at this machine again, we have some forward progress, at least I assume so. It still doesn't boot, but after studying the schematic, scratching my head and making a face, and then metering across all the caps to check to see if I had shorts, I noticed a short...

Okay, so the AA16870 arrived and did not solve the problem. In spending a ton of time digging through atrocious search results for a how-to on disassembling this model of PSU, I kept seeing the recurring theme that the soft power circuit on the IIcx and IIci are frequent problem areas on these...

Sadly, the Mac hoard skips from the IIsi to beige Power Mac G3s, so it looks like I have some reckoning to do: track down a spare or replace innards with one of the Meanwell-based kits. I guess I can also probe components on the top board before giving up! Thanks for the suggestions on where...

Hi folks! I have a IIcx that refuses to boot with its recapped Astec AA15830 power supply, or the AA15831 that I borrowed out of a IIci. After painstakingly rechecking all of the caps I replaced for accidental shorts between pads and traces, feeding the board a current-limited input on +5 and...

Welp, turns out what I was witnessing was the result of pins 43 and 44 of the SCSI chip having a barely visible solder bridge. I was going to go in and scope to see if the connections between VIA2 and the SCSI controller were doing anything, and started by looking at the quality of the solder...

Rereading from your thread, I noted discussion of both internal and external termination, and it's a little unclear to me: did you just build a bridge connection with the 470 from REQ to +5V-TERM and with the caps between +5V-TERM and ground? Or did you modify an internal terminator? If the...

We found disks and after learning dd needs the bs=84 and skip=1 flags, and a servicing of the SE/30's drive, I was able to get the machine booted off a 6.0.8 disk! As expected, the BlueSCSIs did not show up on the desktop. I shut down, installed a terminator (per the other thread's...

Presumably it'll come as no surprise to more seasoned forum members: our IIcx and IIci, like the IIsi I've already started work on, have vacant ROM slots. It'll be on to checking RTC and VIA health and cleaning the drives in the working SE as next steps for this machine while I work to find...

Oh right, the boot image: I've been working off of the OpenRetroSCSI-6.0.8-500M image located via BlueSCSI setup guides. Normally I'd say "it boots the SE and the two Macs Plus" but I'm starting to figure out that may not mean a whole lot in the grand scheme of things...

Ah, no I did not know that the machine can't talk to an HD20, and I'm guessing the TashTwenty emulates that based on the name. So in a sense, the emulator not working *is* a ROM issue, at least I can be happy with that assessment. So since further research indicates the other ROM simms to which...

Hey folks, an update here: I finally got a floppy emulator device. After confirming it works with my functioning SE, I connected it to the SE/30 and attempted to boot. No dice, with the internal BlueSCSI connected along with the TashTwenty on the external floppy port, it gives up the exact same...

Hi all, I'm pretty deep into refurbing an SE/30 that entered my orbit in need of both PSU and logic board recaps. It powers on, plays the chime, runs the memory test while the gray background shows, and gets to the point where it thinks about booting, but will just throw a flashing ? disk...