ThisDoesNotCompute

As a bit of closure, and somewhat of a tease: I got my hands on another SE/30 board that suffered from a PRAM battery explosion. The board is toast, but there are still good parts on it. I swapped four of them over to my original board...and it works now. Expect a follow-up video in a few weeks. Thank you all for your help, I learned a ton!

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Yesterday I soaked the board in IPA for a few hours, then set it out to dry overnight. The problem persists. I'm continuing to test the ROM connections. I've gotten through the muxes and resistor packs (RP4 through RP6) to their respective RAM slot pins, all are good. Next I'll work from the RAM to the glue chip I guess, and also check out the SCSI chip. Hare are some photos of the board after cleaning: https://imgur.com/a/5r6or6s

Yeah, after starting to go through the rest of the schematics I realized that all of the chips on the board use only +5v, and the rest of the rails are just passed through to other components (expansion slot, floppy drive, etc). And correct, there's no boot chime. I tested all of the pins on the ROM SIMM slot to the muxes (D4 through D19, and UJ2/UI2/UJ3/UI3), continuity good there. I'll look closer at the C12 area, and after that, go back to the ROM muxes and keep testing forward from there. I'm also planning on giving the board a good soak in IPA, since all I've done so far for c

So the floppy voltage thing was a red herring. This page says -12v should be present on pin 5 of the external floppy connector: https://allpinouts.org/pinouts/connectors/data_storage/macintosh-external-drive/ Turns out that's not true, at least for the SE/30. I found an original schematic for the SE/30 logic board, and it says pin 5 is simply not connected: https://museo.freaknet.org/gallery/apple/stuff/mac/andreas.kann/SE30_SCSI1.GIF I also measured the voltages present at the 14-pin connector. They're a little out, but not too horribly (and this is without a

Thanks for sharing my video! I poked around the logic board a bit recently, and here's what I've found so far: --All voltages present (+/- 5v, +/- 12v) at the 14-pin connector from the analog board. --Continuity from the 14-pin connector to the edge connector for those voltage rails. --All voltages present at the external floppy drive connector...except for -12v. Hmm. Schematics show that cap C9 handles the -12v rail. It looks OK visually, but I might remove the new cap and take a closer look. RAM and ROM SIMMs have had their contacts c