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.
Nigel Wadsworth 🇦🇺@chockenberry I wonder if anyone has collected all versions of the signature variations. Here’s mine. Signatures are on the raised bit as well.
@nygl Your part number shows “Rev E” and mine looks like it’s “L”. That’s a pretty good indicator that there are a lot of variations 😉
Also looks like you’ve got a leaky backup battery!
@nygl Ooof - the leakage on the mains input in last photo.
Also wondering if the 240v versions have a different mains connector there (I know the analog boards are different).
@chockenberry Yes, I bought a re-cap kit for it, but the more I look at it the more worried I am about traces and other components.