Zenith Chromacolor

 

In the late 1950s, many electronic manufacturers, such as RCA, General Electric and Admiral, were changing from hand-wired metal chassis in their radios and televisions to printed circuit boards. While circuit boards save time and errors in assembly, they are not well suited for use with vacuum tube equipment, in which high temperatures are generated that can break down boards, eventually causing the boards to crumble if one attempts to remove a tube. Zenith, and to a lesser extent Motorola, avoided this problem by continuing to use hand-wired chassis in all their vacuum tube equipment. Zenith kept circuit boards out of their televisions until the Chromacolor line of the early 1970s, and even then used them only with solid state components, mounting the four tubes used in the Chromacolor "4 tube hybrid" on the steel chassis. Zenith began using circuit boards in radios when they converted to solid-state in the late 1960s, but even Zenith's early transistor radios were completely hand-wired with socketed transistors. For many years, Zenith used its famous slogan, "The quality goes in before the name goes on." Due to the use of this chassis construction and high-quality components, Zenith televisions and radios of the 1950s to 1970s found today are often still working well, needing little work to restore them to like-new operating condition. 

~ edited from Wikipedia