How to salvage a power tube that has a crack

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apophis

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Received a quad of Winged C 6L6 from reverb, and one has a small crack in the center. I have had them a few days and barely noticed it, not sure if they came like this or it happened here. So, vacuum is not lost so I dont know if the crack is only superficial. Is there any thing I can put on it to "seal" it? I dont want to ruin it and lose the quad. I was thinking maybe some super glue , but not sure if it will take the head once they are on
 
Repeated heating and cooling of the glass will cause it to lose vacuum and allow for internal arcing which could take out screen grid resistors or even worse your power transformer. I’d never ever choose to run compromised vacuum tubes in my amplifiers by choice. Don’t let the NOS stamp go to your head - the tube is done. I’d expect 1/4 refund from the seller as you were sold four operable tubes free from mechanical damage.
 
glpg80":axabnm19 said:
Repeated heating and cooling of the glass will cause it to lose vacuum and allow for internal arcing which could take out screen grid resistors or even worse your power transformer. I’d never ever choose to run compromised vacuum tubes in my amplifiers by choice. Don’t let the NOS stamp go to your head - the tube is done. I’d expect 1/4 refund from the seller as you were sold four operable tubes free from mechanical damage.
This^^^
:yes:
 
apophis":rihlqdgx said:
Received a quad of Winged C 6L6 from reverb, and one has a small crack in the center. I have had them a few days and barely noticed it, not sure if they came like this or it happened here. So, vacuum is not lost so I dont know if the crack is only superficial. Is there any thing I can put on it to "seal" it? I dont want to ruin it and lose the quad. I was thinking maybe some super glue , but not sure if it will take the head once they are on


Ok are you actually talking about a scratch? Can you snap some macro pictures at an angle to the crack?

If it's a scratch you're fine. If it's an actual crack you would have lost vaccum already.
 
It feels like a crack, about 1 inch long, however it might be superficial (I hope), I also thought that if it had gone trough it should have lost vacuum pretty fast. Ill try to post some pics this afternoon
 
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