Selenium rectifiers in Zenith radios

[old_coot88]

In 30+ years in the trade, I never saw a selenium (even big ones in TVs) short out. As they age, they do develop reverse leakage in addition to increased forward resistance, which leads to overheating and eventual failure. The hottest cell in the stack determines the failure point, releasing noxious fumes described as smelling like rotten eggs.