Step 11: Finishing touches
Put the two PCBs together: just like you did before in step 6. Push firmly so the pins go all way into the
headers and no metal is exposed on the pin.
Install the 10-pin ribbon cable with the red stripe at the
bottom (-12V) onto the POWER 2x5 header, NOT the 16 pin EXPANDER header.
Step 12: Insert ICs
Each IC has an orientation, the dot or notch should be
pointed towards the notch in the IC socket. Verify you
didn't put the IC socket in backwards by checking that
the IC notch/dot lines up with the notch drawn in white
on the PCB. See photo (the red circles indicate the
notch/dot).
•
TL072 (8-pin) x 7: (all notches facing up)
•
ATTNY2313 (28-pin) x 1: (notch facing up)
Step 13: Take a break
That's right, walk away and do something else. This is a
critical step
especially if you are an advanced kit
builder or electronics person
(beginners tend to check
their work with more skepticism!). There are many
things you can do wrong in building a QCD Expander
that causes it to smoke and destroy components. So
don't rush, have a clear head, and check your work.
Come back refreshed. Look over everything:
•
Check all the solder joints, it's easy to miss one.
•
Verify the ICs and IC sockets are not in
backwards.
•
Verify the diodes have the band pointing to the
line on the PCB
•
Verify the 47uF caps are not in backwards (stripe
to the right).
•
Verify the header pins are not bent.
•
Verify no components are sticking up and
potentially able to short out to something.