In a previous episode, I did a restoration on Macintosh Monitor, which involved a complete
teardown, cleaning, and retrobriting. The monitor came out looking great. And I had
already restored the exterior of the computer in an episode 2 years prior. However, the
motherboard needed some help because when I powered it on, it did this. And that sound
was actually coming from the speaker. If I unplugged it, the sound would go away. The
problem was the capacitors on the board, and I had ordered some replacements. And while
I got the right voltage and capacitance values, they were not physically the correct size.
So, I didn’t get to include that part of the repair in the last video.
But, here we are now, and I’m going to tackle that part of the repair. I love how easy it
is to disassemble one of these LC style computers. Everything comes apart without the need of
any tools at all. Even the motherboard itself will snap right out. Unfortunately, these
90s era Macintosh computers are notorious for having leaky caps. This one is no exception.
And the problem isn’t even so much the loss of functioning capacitors as it is the fact
the electrolyte is corrosive over time. This one is covered in what I like to call “cap
juice.” The longer this is left untreated, the more of that stuff will leak out, and
the more damage it will do. It will eventually corrode away the traces on the board and the
legs on the chips. And as you can see, it is already doing that.
OK, so the first thing I need to do is I need to remove these capacitors. Now, unfortunately,
nobody can agree on what the best way is to remove these capacitors, and there’s like
a dozen different ways you can do it and you can categorize all of the different methods
down into two basic categories. It’s either breaking them off or desoldering them. And
then there’s different ways to do each of those things too. For these, I’m going to
break them off.
OK, so in order to do this, I’m just going to use a pair of needle nosed pliers and I’m
going to grab ahold of these and I’m going to twist. Now, one thing you can do is twist
the thing all the way off, which some people do. Now, what I’m going to do, is I’m
going to grab one of these and then I’m just going to rotate, rock it back and forth
a bunch of times and what this is going to do, is it’s going to cause metal fatigue
in the leads, and eventually it’s going to break off.
Now, the reason I prefer to do it this way is because it is less likely to damage the
copper pads on the board. Let me illustrate this using some tape to represent the solder
pads, and the white paper represents the capacitor leads. I’m going to stick these both down
to the bench like this. On this one, I’m going to use sideways force, which is what
will be happening when you twist the capacitors. And you can see the lead will rip off. But,
look what happens if you pull directly up. And this is exactly what we don’t want to
happen to our solder pads.
twisting these off like this. Now, like I said, I’ve seen many arguments as to which
method of removal is best, and I’ll guarantee there will be somebody down in the comments
saying that I’m doing it wrong. And so if you’re ever considering recapping something
like this, feel free to try other methods, I’m just showing you how I do it.
So, I have one left to remove, and in case you didn’t realize, the leads of the capacitors
are still on the board, sitting right on top of the solder pads, so we’ll have to deal
with that shortly. Here are all of the caps I’ve pulled off.
The next thing I’m going to do is use my soldering iron combined with a little pick
to remove these leads. Now, just in case you didn’t realize how zoomed in this image
is, that little pick I have feels almost needly sharp if you poke your finger with it. It
looks huge here, but I assure you everything you are looking at here is super tiny!
In this case the lead ended up sticking on the soldering iron, which is fine, at least
I got it out. And now we’ll do the next one. And it ended up doing the same thing,
but it is gone. The next thing I’ll do is follow that up with some desoldering braid
to remove the excess solder.
And here’s the board with no capacitors, but still a lot of cap juice everywhere. Now,
I’m going to remove the RAM because I’m going to put this thing in the dish washer.
I’ve actually been told hundreds of times over the years to put boards in the dishwasher.
Now, I’m not afraid of doing that, it’s just up to this point, I haven’t really
had a good reason to because usually I can clean off boards using some compressed air
or scrubbing them with a brush or maybe some alcohol or something like that. And I can
usually get them pretty clean, but not this stuff. So, I’ve also been told that dishwasher
detergent has some kind of anti-corrosive properties to it since after all, people do
put metal things in the dishwasher, right? So, I’m going to give it a try. Let’s
see what happens.
I also need to remove this PRAM battery. Now, believe it or not, I just put a new on in
there recently. However, I noticed it has a date of June 2016, so I don’t know if
that is the manufacture date, or the expiration date. But it does work, and I just want to
remove it for the dishwasher.
And, so here we go. And I don’t mind telling you I am more than a bit skeptical. I’m
not concerned about the dishwasher actually hurting the board, as I spray them with water
all of the time. I’m just not convinced it will clean it off.
OK, so the cycle is complete. Let’s have a look. OK, well, it’s hard to say from
right here, but I think it worked. It’s still very wet. I’m actually shaking a lot
of the water off still. And I’ll follow up with some compressed air to try to get
under the chips and other objects. It’s still a bit wet, but holy smokes. I am really
impressed how clean it looks, especially in the capacitor area. However, it’s not perfect.
There’s still a bit of corrosion in this area here, and also over here on these chips.
So, what I’m going to do is drop a bit of alcohol down on this area, and scrub it really
good with a tooth brush. And that made a significant improvement as well.
So, just for comparison sake, here’s the board before any work was done to it. And
here’s after cleaning. So yeah, I’m very pleased with the result.
Also, while I’m waiting on the board to dry out, I’m going to take this power supply
apart and check the capacitors in there. I actually have 3 of these power supplies and
this is the only one that works. And I did order some capacitors, which I hope are the
correct ones. But I’m going to go ahead and take it apart and we’ll see if it needs
any.
OK, these don’t look bad at all. They are so tight, I can’t tell for certain if they
are leaking or not, but I don’t think so. They definitely aren’t bulging out the top.
I think I’ll just leave this one alone for now.
OK, I put that one back together and just out of general curiosity, this is another
one that doesn’t work and I’m going to take it apart now and see if it looks any
different inside. So I’m getting ready to pull this one apart and one of the things
I noticed is that there’s a lot of corrosion showing up, showing through there. Let’s
see what we’ve got inside.
This one looks a little greasy down there like there might be cap juice, but it’s
hard to say for sure. But there is definitely some corrosion here, but I’m not sure from
what exactly.
So, getting back to the motherboard, I’m going to start by laying down some solder
on these pads. I also want to do the same thing to these capacitors. That way, all I
have to do is heat them up to join them to the board. These things are so tiny, though,
that they end up sticking to the iron. So, I ended up putting them in these little clamps
while I tin the leads, which worked well.
For my first attempt, I tried holding these with pliers while I solder one side, then
the other. And that did work. However, it is really hard. Again, these things are so
much smaller than they appear on camera. So, on the remaining ones, I used my little helping
hands here to hold the capacitor more or less where I wanted it to go, and solder it that
way. Of course, once the first lead is soldered, I can release it to do the other side. Working
with these SMT capacitors has not been the most fun, that’s for sure. But, with some
practice I did get the hang of it.
OK, so the board is now done. I’m going to start re-assembling everything.
I gave it a good check over once again before powering it up, using the original photo to
compare the orientation of the capacitors. And I noticed I actually left one out completely
as you can see here. So I went ahead and soldered that on. And then it was time to test.
And… It works. Not only does it work, but it is no longer making that terrible noise
anymore. So, I went ahead and attached my hard drive emulator, which I’m borrowing
from somebody at the moment. And, it seems to boot right up. So, I think we’re done
here!
I hope you enjoyed this little follow up to my restoration episode. So, the two worst
enemies of these vintage computers is leaking batteries and leaking capacitors. And the
stuff that leaks out of those is like pure liquid evil. So, if you have any vintage systems
that you are planning to store for a while, I would definitely recommend taking them out,
looking for any batteries and removing them, and if they have leaking capacitors, you need
to deal with it right now. Because, you might think, “Oh, well, I can just store this
away and then deal with it a few years from now.” But the trouble is, that stuff will
stay on the board and continue and continue to eat and corrode away at the metal traces,
until you’ll pull that board back out a few years later and it might be beyond repair.
So. And when it comes to these old Macs from the early nineties, they are notorious for
leaking capacitors. And, I would venture to say that within the next 10 to 15 years, literally
100% of them will be not only inoperable, but irreparable, except for the ones that
people have recapped. So, keep that in mind as far as the continued rarity of these.
Anyway, that’s it for the moment so stick around for the next episode and thanks for
watching!