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Great job!

C23 is a reasonable possibility, if it is open circuit. The MOSFET will blow for one of two reasons: excessive current leading to overheating, or excessive voltage from drain to source. I'd guess the latter is more likely in this case, though if you have an IR thermometer that lets you monitor...

I haven't figured out the screen/bezel issue yet, but will revisit it when I eventually recap the rest of the analog board. It's possible that it has just always been that way, and I'm hesitant to do anything stupid in the service of trying to get it to sit flush. Agreed that it is not the most...

I managed to fix the screen issue. As I thought, it was C5 (47uF electrolytic cap). Now it's back to full working order, and I also picked up an external 400k floppy drive for it:   Given that one capacitor was leaking, and the AC line filter cap is starting to show some cracks, I guess the...

Well as nice as it is to keep things original, having things work is usually better. :) It happens with the RAM chips in these machines too, amongst a few other parts. The BU406 is definitely still available, e.g. at Farnell/Element14 and probably most other places.

Just because the flyback didn't fix the problem with the Plus doesn't mean it's not the problem here, especially if (as a 128k) it has one of the early AC-058 flybacks, which were notoriously prone to failure. If C1 (the horizontal yoke DC-blocking cap) is getting hot, that would seem to...

Sorry for the slow turnaround BadGoldEagle. Probably the other one would have been fine too, though I was a little unclear about how it achieved the conversion in both directions (apparently automatically?). Anyway, the type i've used and that you've now found is really simple, just a bit iron...

Both my transformers look like this, though with different brand names printed on the front: http://www.maplin.co.uk/p/240v-to-110v-300w-voltage-converter-vr05f 50Hz vs. 60Hz is not a big deal for the switching power supplies in the Mac. The first thing the power supply does is rectify the...

I'm in the UK, and I've used a simple 220V-110V step-down transformer with an American Plus with no problems. When I bought a 128k a couple weeks ago (also a US model), the person I bought it from was using an identical transformer. So it appears that 50/60Hz doesn't matter.

I looked at the CRT and bezel some more, and I'm not much wiser than I was when I started. There aren't any tabs in the way, and loosening and reattaching doesn't change anything. Instead, it looks like the plastic mounting points on all four corners of the CRT are raised up a little bit inside...

Great project! I can confirm that it runs on my 128k, both from Floppy Emu and from a physical disk: (Slightly stretched display is an analog board issue on the machine, nothing to do with the code.)

I've been collecting 68k Macs on and off for years, but I've never had anything older than a Plus. So when an original Macintosh turned up on eBay within train commuting distance, for a non-exorbitant auction price (< £200), I jumped on it. Here it is:   It came with a keyboard, mouse, and...

Those parts should work fine. It's even possible that the 7905 on the board still works -- they are designed for current limiting without damage -- but it's a cheap replacement so why take the chance? Definitely replace the resistor. The easiest way to check for shorts is to attach the logic...

R29 and U3 collectively generate the -5V supply to the logic board from the -12V rail. If something shorted -5V to ground, the regulator could supply about 1A which would overload R29 and turn it into a big heating element -- about the result that you see there. After removing the parts, check...

I just noticed yesterday that the built-in ROM drive on the Classic includes MacsBug 5.3 (about 26k I think).

It might be a Micron Xceed video card, though from the photos I've seen not the one with the grayscale CRT adapter, which don't seem to have the switch. For example, it could be something like this: http://home.earthlink.net/~gamba2/micron_ebay/736/2049940736.html Still, probably well worth...

It might work. The 12" RGB specs say its horizontal frequency is 24.5kHz. Based on my measurements from this post, 24.5kHz changes the voltages from the flyback by less than 10%. Did anyone ever try it? I have an SE/30 Radius Pivot card (and one of the IIsi cards) so I could try at some point...

That's right -- the pixel clock and horizontal frequency stay the same, but there are more scan lines, hence lower refresh rate. It makes sense to try overclocking to get the refresh rate back up. The constraint, aside from how fast the logic board circuits can operate, will be the horizontal...

Since I guess one compact Mac resolution hacking project isn't enough, I found a relatively easy hack to get extra vertical resolution on the SE/30 with no analog mods at all: As the screen shot shows, this Mac is running with internal video at 512x406 resolution -- 64 more lines than...

Yep, that was it! Found the spare CPU and it booted right up. :) For what it's worth, it boots fine without UB11 installed. It even has sound, though presumably only on one channel. I bought this board because it was socketed. I really wouldn't have expected that, indirectly, that was also...