Finalize power board layout and component selection

[dkonigsberg]

This task is basically a placeholder to cover a potentially endless process of nitpicking that needs to be put aside to make real progress on the rest of the project. This issue is to cover any changes after commit ae0389b94e9373f0d56c7953cbd01af74e56ad83, and refers to process in the context of the state of things at the time of that commit.

The power board has a number of elements for which we can spend an endless amount of time changing our minds, which include:

• Whether to use Bulgin or Schurter IEC320 connectors (latest update is Schurter)
• Which connector to use for connecting the power switch wires (currently using Molex 768290002, Mega-Fit dual-row series)
• Exactly where to position the power switch wire connector, due to mechanical clearance concerns
• Which AC/DC converter to use, though the current choice (Cincon CFM06S120-E) seems to be a good fit. Alternatives include the CUI PSK-6B-S12 or the Mean Well IRM-10-12.
• Exactly which board-to-board connectors to use, though the current JST selections are probably fine. Still unsure whether to use the horizontal or vertical variants, however.
• Exactly where to position the two relays, the internal fuse holder, etc.
• Exactly where to position the J2 connector and the post-AC/DC-converter components.
• Whether there should be a net tie between U2's ground pin and the chassis ground plane

For such a simple board, this is one area where extensive nitpicking is important. This is the only part of the product with a safety concern, so it has to be right. Also, the design/layout will have to be followed up with the assembly of a complete documentation package that includes component data and approval records.

[dkonigsberg]

Finalized for the first prototype build. May nitpick further in the future, but it should be good enough for now.