[drh4683]

Nice find! I'd be willing to bet a filter cap shorted out on you. I have a set with the same chassis, the filter cap was so bad that the picture looked like a mushroom cloud when I first powered it up. I bet yours is totally shorted out. Perhaps this was a bad run of filter caps they used on this chassis as most other filter cans on zeniths held up quite well. The one on mine that was bad was a 2 section lytic, 100,150 @ 400vdc.

It looks like an untouched set as it still has the factory silicon blob that holds the 6LF6 in place. That was another sign of cheapness that you started to see in zenith though. Before, they used to use the wayfer board with springs to secure the HOT, then starting around '73 they started putting silicone on the tubes. Must have been for shipping purposes? Can't really see a reason why thats necessary under normal operating conditions. If I ever need to test an original HOT with the silicone, I carefully cut it with a razor knife near the socket so when I put the tube back (if its good) it looks original like nobody touched it.

Im pretty sure that a belfuse was just a style of connection or construction, not really special electrical characteristics. The value of the belfuse is usually rated in milliamperes after the hypen of the part number thats stamped on the case.

Another pointer,
be sure to clean that goop off the CRT by the anode and remove the yoke too. Clean up the anode connector as well as they break down and become tacky/oily which is where that all originates. I had a 12A12C52 chassis set that had no high voltage because that oily mess ran down the edge of tube right into the yoke like on yours and it corroded the wires shorting it out.

As for those cabinets, I think zenith was one of the first to really skimp on cabinet quality. They really produced some cheap cabinets starting in the early-mid 70's. All things considered, I'd appricate a cheap cabinet with quality components vs the other way around. IMO, once zenith let the chromacolor II chassis go around '78/'79, the quality was gone and both cabinet and components became cheap. The system 3 (introduced in '78) and newer really doesn't interest me for the above reasons.