Finally fixed my LC II power supply!

Happy New Year! In other news: I finally fixed my Macintosh LC II's power supply. This drove the machine that my Mum wrote her Master's thesis on way back when my parents lived in Singapore. The hard drive inside still runs, and thanks to a donor motherboard I got off eBay, I now have a fully working unit. I made sure to back up all those family files using an old SCSI PCI card I had laying around in my junk pile. Praise old tech! I hope to do more updates on this particular machine in the future when I've made more progress and have time. Nevertheless, let's get into the little story for today...

Certain capacitors in this TDK supply are known to go to Hell with age; however, not all need be replaced, as the Japanese-made Nichicon ones are still chuggin' along just fine. My first attempt to revive the TDK a couple months back was a bust, and so I left the project to idle on the backburner. With the grace of uni's holiday break, I've been blessed with tons of time to fiddle around with electronics in my basement workshop.

Before I show off the humorous picture of my handiwork (every time I work with wires and other small electronics, I have more and more respect for the nimble hands of surgeons) I'd like to preface it with my ignorance for most things under the umbrella of "electrical engineering." In my second go-around to fix the TDK, I completely destroyed one of the capacitor's contacts, including my first attempt to salvage it from before. So, in my ignorance, I connected a bodge wire to a spare area on the PCB (bottom left in the picture) which I saw was free from other pins. But, I didn't take the necessary couple seconds to consider that this "island" wasn't at all connected to my capacitor's pin.

When I go to turn on the power supply, it doesn't click. This was an immediate warning sign because so-called "switching" power supplies, like this one, have safety mechanisms to ensure they don't turn on when they ought not to. Due to my stupid error, the logic that provided this safety mechanism was busted, so the power supply gladly accepted the electricity and began to get warm. Once I realized, I quickly unplugged the unit and set to work rectifying my error.

As you can see below, the little island my pin was connected to was pretty isolated, and so I had to follow its itty bitty path to an area which provided ample space to safely and easily connect a wire.

After all that hassle, I present you with my finished product (in all its gnarly ineptitude):

Photo showing my crappy handiwork, bodge wires and all

To please those who, like me, love seeing old machines fixed up and working again, here's a photo I just took of the LC II booting up with its like-new power supply courtesy of yours truly:

Photo of the supply successfully booting up a Macintosh LC II

Glad I have at least this piece of the puzzle worked out. My next step is to tackle the LC II's motherboard itself. The caps leaked all over, and I bought new ones to replace them. However (yet another subordinate conjunction) I've gone and fuzzed up the contacts there as well. Once I get new caps in the mail whose pins are easier to work with I'll get to repairing that trusty Motorola 68K board. If you enjoy seeing nasty bodge wire jobs, stay tuned for that post (haha)!

Lastly, a couple quick personal updates. First, my flight to Boston is all set and I've got a nice, cheap Airbnb booked close to Cambridge and all its founts of knowledge and intellect. I am psyched outta my pants for that trip, and one can bet their pretty little Weller soldering iron I'm going to be writing a lot about it.

Second, I'm having a grand ol' time memorizing my lines as Gonzalo for the production of The Tempest that I'm in. Feels good to be in a serious theater company whose members are still lighthearted and filled with dramatic energy.


P.S. If anyone is interested in the capacitor replacement process (such as if you have one to fix up yourself) here is the link to the instructional video I used. Many thanks to Francesco!