Craig HockenberryThis was unexpected.
(Probably some 40 year old caps releasing their magic smoke.)
Found the culprit at C38. It’s a common fault for the RIFA capacitor that’s made with foil and paper to fail spectacularly due to age.
Thankfully it’s a cheap and easy fix thanks to eBay. I’m going to replace all the capacitors on the analog board as a preventative measure, too. Nothing leaking … yet.
AND EVERY ONE CALLS IT RIFA MADNESS SO THATS JUST A BONUS IF YOU KNOW WHAT I MEAN
This 512k Mac also suffers from another common problem: a floppy drive that won’t eject the disk.
The failure point here is a cog made from a plastic that softens over time. In the image below, you can see how the brass gear has carved out a gap in the teeth of the leftmost cog.
Again, an easy fix with 3D printed parts from eBay.
The best part of opening an original Mac is seeing the signatures of everyone who worked on it.
Sadly, on this second iteration of the Mac (after the original 128k version) some of the names are obscured by some additional plastic. This includes Steve Jobs and Bill Atkinson.
Working with 40 year old plastic is tricky. The only casualty from today’s efforts was the programmer’s switch.
I doubt I’ll be doing any coding on this Mac, but I’ll still replace it for nostalgic reasons. I may even have a spare in my attic!
One more thing:
If you ever plan on opening an old Mac, watch this 10 minute video first.
I could literally save your life.
Discharging the CRT in a compact Macintosh
John Moltz@chockenberry This is the part that has consistently stopped me from opening either of my classic Macs.
Chris Gervais 🎸🥁💻@Moltz @chockenberry It’s pretty easy to create a discharge cable. However, 12 year old me had zero knowledge of this and was YOLO’ing inside my Mac Plus. But, I’m Gen X so I’ve been through more dangerous situation
@chrisgervais @Moltz 15 year old me saw some doofus in my Electronics class get zapped across the room while digging around in an old TV. I’ve been very careful around the business end of a flyback transformer since then.
Nigel Wadsworth 🇦🇺@chockenberry @chrisgervais @Moltz You can't get your Apple Technician certificate until you've been zapped by a classic Macintosh CRT, an Apple II monitor, *and* some sort of Apple Trinitron-based display. Preferably not a 21-inch colour...
@nygl @chockenberry @Moltz Those big Trinitron displays could power a city with charge stored in their flybacks!