And speaking of vacuum tubes. The other day I mentioned that the 7586 nuvistor in the Type 321A is taking upwards of 30 minutes to stabilize. Well all of sudden the little nuvistor “woke up” and within 5 minutes or so is stable. Which is more than acceptable. I've seen this before especially with nuvistors and to a lesser extent with larger tubes. I have a theory as to what process is occurring here and I'd like some input.
As you know nuvistors are very small and almost look like a transistor. Inside there is a “getter” and it's function is to absorb any free gasses or ions floating around inside the vacuum envelope. Well after many years...20, 30, 40....of no applied power these gasses and ions may start break free from the getter and poison the cathode. And because of the small structures involved it doesn't take much for the cathode to get contaminated. Initially powering up after all those years those contaminates need to boil off the cathode and be absorbed by the getter again. But it may take many cycles for the cathode to clean itself.
Make sense or am I off base?
Makes sense to me, Shango066 on youtube has had this happen with old TVs/radios that haven't been used for decades, they can get better with extended use. But not always, sometimes they are knackered and that was the reason they got retired from use in the first place.
Re: trying to rejuvenate Trintron CRT's from a few pages back, Shango066 has tried & failed with a knackered one at some point in the last year, I'm sure he said it rarely works with Trintron CRT's and can sometimes make them worse. If a brightner was fitted then it's probably a waste of time trying to rejuvenate them.
David
Shango066 is making this claim from a statistical base of one?
I worked on Picture Monitors for 10 years, & found that, as I believe I commented, you get about one, or maybe two rejuvenations out of Trinitrons, with delta tubes being much the same.
If you are using Monitors in analog TV broadcasting you can't get away with the sort of results you could tolerate in domestic use. where you might get more chances.
In fairness, I was doing this between 1989 & 1999, so the oldest pix tubes I "rejuved" were probably not much more than 25 years old at the maximum, most being less.
A 40 year old pix tube of any type is unlikely to be successfully revived, especially, as not knowing its history, it may have been rejuvenated several times already.
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Topic: Test Equipment Anonymous (TEA) group therapy thread (Read 14815728 times)