B&K 465 acting strange
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I really love my trusty B&K 465, but when I went to use it tonight on a tube, I noticed that when I set the switch to emmision, whichever color I set the tester to, glowed blue inside the tube. I made sure I had the voltages set to the book. 40 volts on G1, about 275 on G2. I could also feel a very slight AC voltage on the tester itself at all times. What's going on with my beloved 465?
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It's not the tester, looks like you have a gassy CRT.
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Both RCA Hi Lite tubes that I tried did that. Are they both junk? They both looked fine before I took them out of sets.
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No idea, but my Heathkit GR-370 had a RCA Hi-Lite 25BCP22 that was the weakest CRT I've tested yet. No blue glow though.
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When I test a gassy tube on my B&K 466 setting the cutoff knob (which states to adjust meter up by 2 divisions) will have an all-or-nothing response from the needle and there will be blue or purple glow in the neck...The worse the tube the bigger the glow.
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These Hi Lite tubes (that I JUST de cataracted) both test perfectly fine on all my testers. Even on the 465, there were no anomalies when setting cutoff, and they both tested between 80 and 90 percent.
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I'm pretty sure that means the crt is full of air. Why not just test a known-good tube? You know... like one that's actually inside of a working tv that you have watched recently? I know you have at least one -_-
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My guess is that emissions will drop quickly under regular use, or suddenly drop to nothing when the filaments open.
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If a lot of heat was used for cataract removal, it may have gotten to the guns and compromised the seal at the pins. |
I could've sworn gassy tubes glow a bright purple, not blue due to the discharge of ionized oxygen. I have some tubes that glow blue on the neck glass due to electron bombardment. Is the tester responsive at all?
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I hooked the tube up to the chassis out of the cabinet, and the tube works just fine. I also tested a Magnavox 25VCXP22, and it did not have any blue glow.
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If you've got raster your tube is not gassy (or at least not very gassy). When a CRT is full of gas you won't get a raster and the HV will probably arc to the gun and the HV system will cry bloody murder.
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