Abstract: A cassette light retrofit adapted to be received in a housing portion of an existing lighting fixture from which the light tubes and door frame with diffuser have been removed comprises an open cassette enclosure having a door frame and diffuser closing the enclosure; a lightable tubing array in the cassette enclosure; a power converter in the enclosure connected to energize the lightable array; and, said cassette door frame being attachable to the fixture housing portion to replace said fixture door frame with the cassette enclosure being in said housing. The power converter uses 8 windings with isolation to improve the tracking efficiency of the sensing windings for accurate high frequency power application for the load. Also, an A.C. winding permits dimming of the lamp load by filling in chunks of voltage deleted by the dimmer.

Abstract: The invention comprises a fluid-tight light box containing a cold cathode light source activated by a high frequency ballast circuit small enough to be contained in the box.At least the box bottom interior is coated with a crinkle or matte finish to cause uniform brightness at or adjacent to a window in the upper side of the box. The ballast circuit is preferably also coated to avoid shadow effects.A milky element may comprise the window or be positioned adjacent thereto to comprise a light diffuser for a transparency adjacent thereto or the transparency may be coated on its reverse side with a diffuser coating.This display or portrait exhibitor may measure less than 2 inches thick and this is the reason the light reflective path and materials are so critical.