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
Not great timing with #MARCHintosh having just ended, but I finally have the time and ability to work on restoring my 512k Mac.
(Go back in this thread to see what has happened so far.)
I’m going to replace all the capacitors on the analog board. First up is the blown RIFA:
Still a long way to go though!
There are a couple dozen capacitors to replace, and desoldering is slow and meticulous work (you don’t want to damage the pads on the circuit board). Soldering is much more fun (and something that I’ve been doing for over 50 years!).
It’s also helpful to have some markers showing where to work and the polarity of the cap. Lots of flipping of the board and the CRT yoke without them!
Narles@chockenberry having just recently recapped a Sega Mega CD, I feel this in my bones.
Joe's Computer Museum@chockenberry #MARCHintosh is year round, didn't you know?
Source: Me - I helped invent the thing. :D