Quote:
Originally Posted by doogie812
It has been a while since I have been on the site. After my current gig (maybe a few years) this could be rite up my ally. Learning how to weld a new gun on a old tube does not seem like rocket science.
Where do we stand on guns? Is their NOS available for the color roundies? Do the B&W tubes require rephosphor and aluminumizing? How would we deal with toxic chemical disposal? Is it feasible to replace cathodes in guns? Does the cesium alloy degrade on cathodes not under vacuum?
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I've accumulated some knowledge over the years about CRTs. Not everything by a long shot and sometimes I remember things wrong. However I will mention a few things.
Welding glass tubes is not so much a matter of science but skill, harder to get right than it looks. Note that there cannot be too large a bulge where the joint is on the outside (ID of the yoke) or the inside (sliding in the gun). Also it has to be straight.
Some types of guns might be found. There supposedly is a source in Russia.
B/W CRT do not always need a new phosphor, I think it would be a good idea but several people that plan to re-gun tubes do not plan to do it because of the added complications. If a tube is not aluminized it requires a different type of gun (older design) and those might not be available. Perhaps in that case the old gun has to be reused and the cathode replaced.
It isn't feasible to re- screen color tubes with the state of the art.
I don't know about waste chemical disposal. Depending on local regulation a small amount may not be a problem. "The devil is in the details."
New cathodes have a combination of carbonates (barium, strontium and calcium?). Our Polish friend would know. After the vacuum is applied the cathode is heated and carbon dioxide (CO2) (and perhaps H2O) is released from the cathode leaving the oxides. If the cathode is exposed to air the cathode absorbs CO2 and H2O but not in the right way so it is ruined.
You also have to install a new getter, which I believe contains barium and maybe another metal.