Re: Rejuvenating Magic eye Valves?
In my experience, magic eyes fail because the phosphor stops emitting light, not because the cathode stops emitting electrons.
You can tell that the cathode is OK by measuring the target current and comparing with a new one. The target current is generally OK, just a shame that the electrons hitting the target stop making it fluoresce.
A higher target voltage might enable arriving electrons to penetrate beneath the surface, and excite non-poisoned target phosphor - there has been some success reported with this, and I've seen it myself - but it does not make the indicator looklike new again.
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