The Low End Mac Mailbag is a collection of articles, pictures, submissions, etc; from LEM community members and individuals alike. Sometimes if something is particularly rare, interesting, or unique, I like to reach out and see if they would like to have it featured on the website as well. It’s always fascinating what people come up with or have stumbled into.
Today’s article is about a Macintosh Quadra 700 Prototype, and how LEM member Dan Schnur saved it. The following parts were written by Dan.
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Saved from the recycler
A quick preview of a computer that was just saved from the recycler. More to come!
Opening it up
More on the computer I teased about last night before a dust storm shut me down: this is a pre-production prototype of what would become the Quadra 700.
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I’ve only ever seen two others at this stage. The giveaways are subtle but telling – no silk screen on the front, a smooth, untextured case, and a rear panel with no engraved writing. From what I’ve learned, adding texture to the injection mold is one of the very last steps, since once it’s done, there are no more modifications that can be made to the mold.
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On to testing. First, I checked the logic board—no shorts! That’s important because tantalum capacitors like to fail by shorting and sometimes exploding when powered. I also inspected the power supply: it’s fixable, but I decided to leave it original.
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To keep things safe, I disabled it by disconnected the input board from the main board and taped it off. I’ll use a different supply for testing so this one can remain untouched.
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And now the good part: while the original hard drive was long gone, I had a period-correct replacement from a IIfx. I set it up, plugged it in, and with my test PSU… it booted! More details coming soon.
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Fixing the PSU
Since I have spare PSUs, I don’t need this one to run. My real goal is to preserve the prototype in its most original state for as long as possible.
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The options are, as I see it:
I know how to handle the work (40+ years soldering everything from junk to museum-grade hardware), but I also know the risks – trace damage, stressed parts, and the fact that every touch of the iron takes something away from originality. If this were yours, what path would you take to balance preservation and authenticity?
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My thoughts are that if I put new capacitors in it, sometime in the future they are going to also need to be replaced. No capacitor I’ve ever seen has a life span measured in decades. No mater what, every year or so, it’s going to need to be inspected for leaks. It’s part of the game with vintage electronics. I also have another identical power supply that is freshly recapped, so it’s not really anything that needs saving. Still though, re-capping involves removing lots of hot-melt glue and possibly damaging the really cheap traces in the power supply.
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Making an image of the Boot ROM
I made an image of the Prototype Quadra 700’s “Terror F1” ROM. I captured the ROM image, but for some reason I get 1,048,862 bytes. Emulators can’t take one > 1024k. That’s what is odd.. I think copyrom is having issues. Nope, they don’t work with any emulator I have (yet).
Just for fun, in ran strings to see what I could find. There are a few messages in from developers in them:
“SO…WHAT ARE YOU STARING AT?”
and so on… and a message referring to the code name of the machine.
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