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Also, those are what machines I have to test with: one SE; one SE/30 (full machine); one SE/30 logic board with battery damage; one LC; and one IIvx (just arrived). The others - as of yet - probably don't need PSU replacement: a Gossamer G3; a grey G4 tower (I forget which rev - it's not the...

The schematics indicate that the line in question (A2) is common to all the other devices on the board that have an address bus connection. If the trace for A2 were being pulled up by contamination; the machine would not boot. This implies that pin 4 of UC8 may be corroded or the trace leading...

That could not have been cheap... you'd think though, if you're spending all that $$$ to keep your stuff safe from the Soviets (or, uh, Captain Crunch's buddies) that you'd want more RAM than just a 1Mb?

I’m going to see if I can get a few more done before sending them off; in the hopes of getting a better deal on shipping. SE & SE/30 as well as whichever variant works with a IIvx (I’d have to go look that up; I think it’s the same one that works with a IIcx & IIci?) I’m also waiting on some...

OK, now I think it's ready...

I think this is ready to go to PCB manufacturing... Actually, I think I'll add pads for a DPDT switch, so if you are using the 4-pin molex supply instead of the ATX supply you can turn it off without having to unplug the power brick.

I have a preliminary design for the LC almost done; still needs silkscreen editing. See https://68kmla.org/bb/index.php?threads/lc-lcii-power-supply-replacements.38365/ and scroll all the way to the bottom.

Um... we're sure it's an LC card? As in the 020 that got half it's bus width stolen??? What would it have been used for?

I don't think it's the VRAM chips themselves; because you would have a different pattern showing on the screen if that were the case.

Initial guess: I think it's UC8; and that pin 4 of that chip is being interpreted by the chip as always high; causing all writes to the first 16 bits of a row to go to the next 16 bits; leaving the first 16 bits uninitialized, resulting in the stripes of garbage data you are seeing. I am...

You might have already seen this, but google spat this back at me... http://myoldmac.net/SELL/AppleMacVideoCards.htm Perhaps if you dropped him a line, he might send you a copy of the software for the MegaScreen cards he has listed - if you're lucky, perhaps they used a unified driver for all...

I’m mostly guessing based on how I would do that at that time in history… I suspect that it doesn’t require any software. Just attach the Killy clip to the 68000, hook the board up, and route the display cable out the case (thru the security lock hole perhaps?). I suspect that the board...

Well… it appears that my Google-fu has failed me. Does anybody know where datasheets for the CRTs used in compact Macs might be found? I’m trying to find the requisite information that one would use to design an analog board to drive them (no specific plans at the moment, I’m just investigating...

Ask the seller to use two layers of heavy cardboard on the outside when packing the machine… and perhaps a piece of wood (thin plywood, chipboard, particle board, etc) or something similar on the face of the machine to protect the CRT from anything sharp (like the corner of a crate being shipped...

OK, I know from those photos what is going on, but I’ll have to refer to the SE/30 schematics to come up with a list of possible reasons why. Basically every other 16 pixels of the video memory is not getting written to by the CPU; which on this machine means two bytes of VRAM… and here I’m...

Fume extraction of some sort is important. An open window with a fan, or any of the dedicated soldering fume absorbers (made from a fan with an activated carbon filter attached) will work. You won’t breathe lead or other metal vapors because soldering temperatures are nowhere near what it takes...

As for soldering equipment; first you’ll need a proper temperature controlled soldering station (not just a power setting - it should have a thermostat in it that you can set to a specific temperature). I’m partial to stations that take T12 style integrated tip/heater cartridges because they are...

If you have a battery that’s leaked, you’ll want to use a diluted solution of white distilled vinegar first to neutralize the alkaline fluid; and then baking soda in water to neutralize the vinegar; followed by a thorough rinse with water, and then spray it with isopropyl alcohol to help clean...

As mentioned above, if this is your first soldering project DON’T start out on your Mac! Get something common, mass produced, cheap, and that nobody cares about to practice on first. Broken DVD players, clock radios, or or WiFi routers are good candidates. Or just let somebody who already knows...

Mmm… well, I suppose the 68k architecture could have gone the way the x86 did: a pre-execution translation stage to turn the CISC opcodes into RISC-like micro-operations; issued to multiple execution units in parallel, and a virtual core architecture to extract parallelism from multiple threads...