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In Reply to: Re: "getter flash" is translucent, milky white in top of output tube... posted by Robert H. on August 17, 2002 at 19:16:52:
If a tube loses its normal bias and fries, it will turn white - not erroneously grey....
Follow Ups:
Some industrial "control" tubes' getters turn white as they age to indicate useful life left, but you'll never see them in consumer equipment. Just some trivia.
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No... fried tubes show anode discolouration, and sometimes getter as well, but never white/milky. White milky means air is present.The only linkage I might draw is that if overheated badly, THAT might cause the tube to crack and let the air in, but is was the air, NOT the heat, that sent it white/milky.
I've had about 1/2 dozen power tubes fry and not be able to bias; none of them turned white. Flashing remained silver-toned. Generally acknowledged that loss of vacuum creates the chemical reaction resulting in whitening.
No, it will only turn white if the vacuum is lost - if the vacuum has not been breached, there is no oxygen to combine with the getter to turn it white.
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