A method for protecting tin oxide coated solder surfaces against further oxidation and a method for fluxless solder joining of such surfaces is provided. Fiber optic component panels are housed within the fiber distribution frame at respective positions. In one mode of operation a light emitting diode in the interface circuit is optically coupled to a microprocessor for signaling the closure of the onoff switch, allowing the microprocessor to control the power supply through an opto-coupler. The engine generator further includes an engine-side partition and a generator-side partition fixedly disposed within the soundproofing case to define a chamber to be cooled that houses sections of the engine and the generator that are to be cooled, an engine-side air intake chamber that the engine-side inlet faces, and a generator-side air intake chamber that the generator-side inlet faces.