Competition time. Who can see the
mistake I’ve made in this schematic and
on my PCB layout? The clue is here. So,
pause the video now, go into the
comments, and write down what you think
the problem is.
Well, hopefully you got it right. If we
look at the um data sheet for this RGB
LED, you can see this is common anode.
I’ve done common cathode. So pin two
here shouldn’t be connected to ground.
It should be connected to 3V3.
So looking at my PCB layout, um
originally I was thinking, well maybe we
can just cut through the copper and
isolate this pad, but I think that’s not
really going to work. So, what I’m going
to do is I’m going to desolder the LED,
cover this pad in solder resist, solder
the LED back on, and then we’ll just run
a quick little wire from here to here,
and then hopefully our LED should start
working. So, let’s get over to the bench
and give that a go.
So, I was going to use my hot air gun
for this, but then I thought, actually,
it’s probably better to use the mini hot
plate. There is a bit of plastic around.
We’ve got a little button here, and
there’s plastic on the module. So, let’s
use the mini hot plate to um melt the
solder and extract this. So, hopefully
the hot plate is working. It does seem
to be heating up. Let’s see if it melts
the solder.
Oh, there we go. That was fairly
straightforward. Let’s try not to lose
the LED. So, next step, I’ll clean up
these pads and then we’ll try the uh
solder mask and then we’ll put it back
on. See what happens. Now, of course, we
have to say thanks to PCB Way for the
fantastic PCBs. Did an amazing job as
always. All the mistakes are my own. So,
check out a link in the description.
Okay, let’s add a bit of flux.
And then we’ll just clean these pads up.
So, I got my uh solder wick here.
Okay, that’s looking pretty good.
Nice and clean.
And then finally, a bit of IPA 100%
just to uh do the final cleanup.
So, that’s looking pretty good. Um, so
what we need to do is cover up this
ground pad
with some solder resist. Now, we have to
be very careful here because we want a
very thin layer of solder resist, but it
needs to be thick enough that we do get
some insulation. So, I’ve got a very
fine paint brush here. Let’s try dabbing
some on and make sure we don’t get it
too thick.
So,
I think that looks pretty good. Not too
thick.
Okay. Okay, so that should be nicely
cured now. Let’s check it. Yeah, seems
pretty solid. And hopefully if we place
the LED back on,
should be fairly flat. So, it should go
back nicely into position. So, I think
I think that looks okay.
Yeah. So,
next step, let’s put some solder back on
these pads.
Okay, so that’s the pads with some nice
bit of solder on.
So chuck a bunch of flux on as well.
Oops. Lucky disgusting hair. Nice.
So stick some flux on.
Now we go back onto the hot plate and
we’ll try and stick our LED back on.
Give it a bit of a nudge.
There we go.
Back soldered on. So, let’s turn off the
hot plate.
So, a quick clean up again. Another wash
with IPA.
Get rid of that flax.
And let’s do a quick inspection of our
handiwork.
So, like that’s that’s good.
That looks good as well. So, nicely
soldered back on. So, our next challenge
is hooking up
from this pin here
onto our 3V3 pin, which is this second
pin here. So, let’s do that. I’ve got
some very fine
2 mm wire.
So, hopefully we connect from there.
pin two all the way through to there.
So, this should be durable, right?
[Music]
Okay, I think we’re there.
Yay, we are connected.
Good grief. Now, in all honesty, I can
only describe that as a traumatic
experience. I have no idea how people
like Stev Fixes does this so easily.
It’s a nightmare. But it’s done. It
works. So, that’s good. LED lighting