SBRGB
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15
pads before the part installation makes mounting it a lot easier. Set the
lead of the part on the tinned pad, reheat it, now let the capacitor drop
down into the melted solder. Finish up by soldering the other lead and
making sure both solder joints look good.
12. Install C3, the other 1 uF electrolytic capacitor (again watch the
polarity). These capacitors help to smooth out the power supply voltage so
that any glitches will not confuse the micro-controller and cause problems.
13. Install C1, a 0.1 uF ceramic surface mount capacitor. Unfortunately
this capacitor is unmarked, like most small ones of this type. It’s a good
idea to keep all SMT components in their original containers in order to
make identification easier later down the line.
14. Now for your power connection. Install the 9V battery clip. Solder the
Red lead in the hole with the + marking and the Black lead into the other
hole (the one with a lot of copper around it close to the B1 label). If you
plan on using an alternate power source, make sure you use the proper
polarity as described above.
FINISHED!!
Ok, I bet you are excited to go and plug the battery right in but please don’t do
it yet! We need to inspect our work to make sure we did everything correctly.
We don’t want to destroy any of our parts after all!
Check the two electrolytic capacitors for correct orientation. Make sure the
beveled plastic bases are in the same orientation as shown in the parts layout
and the silkscreen.
Check the two ICs to make sure they are in the correct orientation. Pin 1 had
better line up with the pin one marking on the silk screen! If they are installed
incorrectly, we’ll need to fix them. There is a risky but effective way to de-
solder small SMT ICs like these:
•
Use quite a bit of solder to cover all 4 leads on one side of the part
(effectively shorting them all together). While the solder is still molten on
all four leads, use a pick or your tweezers to gently bend this side away
from the PC board a bit. Don’t use too much pressure or you’ll peel the
traces of the other side right off the circuit board!!!
•
Re-heat and use a solder sucker or wick to clean off the excess solder. Be
very careful with these delicate traces if you use a solder sucker. If you
use braid or wick simply hold it in place to remove the solder; sliding the
wick around on top of the pads tends to remove them from the board!
