"...A "half full" chassis..."
A half full power supply chassis can still mean a proper circuit. Maybe the designer didn't want the power supply in the same chassis as the main circuit and/or simply did not have enough room in a single chassis for both circuits.
A half full power supply chassis can still mean a proper circuit. Maybe the designer didn't want the power supply in the same chassis as the main circuit and/or simply did not have enough room in a single chassis for both circuits.