A couple of years ago (Jan. 2021) I got a Macintosh 512K from a friend and fellow collector, Steve H, who I met through Free Geek Twin Cities. I've bLogged about this machine and what I know of it's history before. It's been the earliest Macintosh in my collection and I've enjoyed it quite a bit. Also it's been popular with my guests who have nostalgia for this machine. It has a place of honor in my limited display area and I've occasionally been asked "Is that the Original Macintosh"? I've had to say no and explain that it's the second Mac, but that is looks identical on the outside and that it came out in the first year of the Mac, 1984.
So, I've been considering either downgrading this machine or finding another original 128K machine. One of the main hurdles to performing this downgrade was that this machine had a (slightly) more modern 800K Double Sided Sony 3 1/2" floppy drive in it and the original Mac can only work with the original Single Sided Sony 3 1/2" drives (400K drives). So this project stayed in the idea phase for more than a year. Along the way I was able to acquire a 128K Logic Board, again thanks to Steve H, so that part of the puzzle fell into place.
In the middle of last year (Aug 2022), I was able to acquire another Macintosh 512K, a Craigslist find. The seller told me that he had been trying to get it working but struggling and that he was giving up on the project. When I got home and started to dig in on the machine it became apparent that he had tried to service the early 400K Sony Floppy Drive but it still did not work. I also spent quite a few hours working on that drive and failed to bring it back to function. In hindsight and after much learning and some good advice I realize that I should have spent more time cleaning and lubricating the drive. I mistakenly thought that the drive needed a recap but when I performed the recap the drive head movements became erratic and the drive could not read a disk any more so I set the drive aside for the time being.
As a next step, I purchased a "lower cost" non-tested 400K External drive from eBay. After spending time cleaning and getting the Mechanism somewhat functional the drive would still not read pre-formatted disks. I made another bad assumption and mistakenly thought that this was a symptom of a drive alignment problem. I broke the threadlocker from the Track 0 position sensor and moved that in an attempt to realign the drives. After spending quite a few hours struggling, I also set this 400K Floppy Drive aside and the project went on hold again.
The next chapter of this repair saga begins at VCF Midwest this year (Sept 2023). I was reluctant to buy more 400K drives because of how much time I'd spent and how little progress I'd made on the first ones but I had a very informative conversation with Steve H. at the show. He has repaired many of these drives and he let me know that he's never had to recap one and never had drive alignment problems. At this point, I realized that not only was I "barking up the wrong tree" but also that I would probably need another drive mechanism in order to move forward with the project. On the final day of VCF when people had started packing up there was a person selling a large number of old Macs and they were willing to take offers. I got a great deal on a lot of items from this seller that included a 400K drive mechanism that had not sold earlier in the weekend. As a bonus they included a second 400K mechanism, so I had two more drives to try to service and repair!
Back at home after VCF I was better educated about what to do (and what not to do) with Sony 400K drive mechanisms. I spent more time cleaning alot more and I thought I'd share some of my lessons learned about the drive cleaning process. Cleaning for these drives has two phases, the first is cleaning the drive inject / eject mechanism. The grease on these drives that I've serviced has all been dried up so hard that the mechanism won't move at all. I used alot of Isopropyl Alcohol to try to remove as much grease as possible then start lubricating the mechanism with 3 in 1 oil. Getting the mechanism loose starts with the small flipper mechanism half way down the right hand side of the drive as you face the front of the drive. Once the manual inject / eject works smoothly the drives can be powered up and run. Phase two of the cleaning is focused on the leadscrew that moves the read / write head, none of these drives worked until I had carefully cleaned and put some lithium grease on to that. I now had 400K drive mechanisms that I needed to move forward with the project!
So, by replacing the drive and swapping the logic board, I have my Original 128K Macintosh from 1984 up and running, along with an External 400K floppy drive...
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It's cool to be able to boot the original Mac Demo disk as this is the only computer I have which can run this software.
Do you have any memories of working with the original Mac? Do you have an original Mac? Let me know in the comments below, or send me an email, my email address is in my Profile on the right side of the screen.
Nice work! Glad that you are up and running!
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