Portaberry Pi Frankenstein/Zombie remix plus flat face case unit mod

Update 5/31/2015 -- I had some trouble with the amplifier wiring and with user Veladrin's help I changed the wiring. A new diagram (rev.3 is posted).

Also -- note in the step-by-step the configuration instructions are for RetroPie 1.9 -- for any newer releases, some of the directories have changed. I plan to post an updated how-to with new instructions, and this will also include a new design for use with the RPi 2.

This is a set of modifications to 3Derp's awesome Portaberry Pi design. B