[sdiy] reminder: check power first

[Kenneth Martinez]

Made quite a bit of progress on my synth this weekend...but...all you
experienced DIYers can chuckle at this:

I wasted a good amount of time trying to figure out why one circuit which
used to work stopped working.  Turns out the -5V power lead to that board
was poorly soldered and came loose; once I realized this it was a quick
fix.  DUH!!!

Well I won't do that again...for at least a little while ;-)