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Old 7th June 2015, 04:44 PM   #1
john65b is offline john65b  United States
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Default What the hell caused this?

I turned on my system this am to hear a nasty hum...both speakers. I quickly shut everything off and swapped preamp - all was fine - no hum. I looked at my preamp (Aikido all in one 6922/6H30) closer and found one of the two 6922 input tubes smoked on top - after looking a little closer saw a gaping hole in bottom of tube at the knuckle...what the hell would cause this? I am glad I did not destroy anything in my system....replaced the EH6922 and all good again..

See pic... bad manufacturing defect? The pre has not been moved for months....
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Old 7th June 2015, 04:47 PM   #2
lexx21 is offline lexx21  United States
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Most likely just a defect in the glass.
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Old 7th June 2015, 05:38 PM   #3
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Air leaking in does happen to the best of tubes. And it hurts when it affects the expensive ones.
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Old 7th June 2015, 05:41 PM   #4
Merlinb is offline Merlinb  United Kingdom
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Suspect other members of your household...
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Old 7th June 2015, 06:23 PM   #5
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you did not get the WAF approval on the tidyness of your speaker cable layout...

and she kill your belove tube in an act of retributive justice

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Old 7th June 2015, 06:53 PM   #6
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The white stuff is the oxidised getter metal that was disposed on the top section of tube's interior surface. The tube must have drawn air somehow. A bent pin will do that sometimes...
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Old 11th June 2015, 09:41 PM   #7
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Originally Posted by Merlinb View Post
Suspect other members of your household...
I have them trained to simply tell me if something was damaged. Its far cheaper in the long run and I myself have broken enough things through foolish mistakes.

Then again.. do you have a cat?
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Old 12th June 2015, 05:11 PM   #8
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Stop blaming everybody! It's a defective tube. It happens!!!!
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Old 12th June 2015, 05:42 PM   #9
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Originally Posted by Rodeodave View Post
The tube must have drawn air somehow. A bent pin will do that sometimes...
I'm thinking that little hole near the bottom has something to do with it.

Now we just have to solve the mystery. Who in John's place is the culprit and what was their motive?

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Old 12th June 2015, 05:51 PM   #10
AuroraB is offline AuroraB  Norway
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Prob'ly just some tension in the glass made the pin pop - repeated heating-cooling does it's thing....
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