Quote:
Originally Posted by earlyfilm
Back in the late 1950s, we routinely replaced selenium rectifiers with silicon ones.... sometimes, especially on transformerless sets, the silicon rectifiers generated a traveling wave that crawled up on the screen. One cure was to add a .01 MFd cap across each silicon rectifier. or from the plus side to the ground. I never understood how this worked, but it usually did.
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Those caps are generally known as "snubbers" in that application.
There's a fast spike produced when the silicon diodes switch-on near the zero-crossing point of the AC wave. Electrolytics possess a small inductance value which allows the spike to ride unfiltered on the B+ line. The "snubber" caps finish smoothing that spike out.