Hi Andy
Your assumption about the display unit being a repackaged display/
control unit from the portable is surely not correct.
I had been looking into building my own "brick" from a standard
portable.
But the architecture of the portable does not allow that (easily).

You can find some images of the portable internals on my webpage.
https://sites.google.com/site/threeuniform/powerflarm
(The source of these images is the documentation for the FCC license
application)

3U