Talk to me about “burning tubes”

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Re: Talk to me about “burning tubes”

Post by øøøøøøø » Wed May 05, 2021 5:14 pm

Blue fluorescence inside the tube isn't an indication of a problem; it's just a side-effect of electrons bombarding the glass envelope. You only really see it on output tubes (beam-forming tetrodes; pentodes, etc) but it's harmless.

You'll sometimes hear old-timers say that funny colors within the plate structure or down low within the tube can be the sign of a compromised vacuum, but that's not a manifestation of that problem I've ever encountered. In that case it wouldn't be long before the getter would turn from silver to white, anyway, and the tube would stop functioning

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Re: Talk to me about “burning tubes”

Post by Scout » Mon May 10, 2021 6:12 am

Thanks for that. I saw blue fluorescence in the lower section of one of the output tubes that was appearing in rhythm with the intermittent sounds that just started, I assumed it was a faulty tube and ordered a new matched pair. I have no experience with trouble shooting amps but being an electrician for my entire life gives me a background in diagnosing circuits and I may have to start with this amp. I have the original old school amp tech in my neighborhood that I usually take things to but I think I’m ready to dive in on this one .

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Re: Talk to me about “burning tubes”

Post by øøøøøøø » Mon May 10, 2021 11:42 am

Scout wrote:
Mon May 10, 2021 6:12 am
Thanks for that. I saw blue fluorescence in the lower section of one of the output tubes that was appearing in rhythm with the intermittent sounds that just started, I assumed it was a faulty tube and ordered a new matched pair. I have no experience with trouble shooting amps but being an electrician for my entire life gives me a background in diagnosing circuits and I may have to start with this amp. I have the original old school amp tech in my neighborhood that I usually take things to but I think I’m ready to dive in on this one .
Yeah, what you saw was certainly a sign of failure!

Most likely it was arcing across electrodes (rather than fluorescence)

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Re: Talk to me about “burning tubes”

Post by johnnysomersett » Mon May 10, 2021 1:01 pm

I used to kill a set of modern JJ's about once a year (well, one out of a matched pair) in my old OR120. If they didnt blow within 12 months, I'd change them anyway as part of the yearly service I did on it...just as a precaution. We played at almost full-volume every week at rehearsal, and gigs throughout the year, so they had a tough life. That amp was biased hot, CRANKED and then pushed with a boost/fuzz so I expected it.

Other than that I think I've had a couple of old ones fizzle out randomly over the last 25yrs of owning tube amps. Hardly anything to worry about really.
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Re: Talk to me about “burning tubes”

Post by Unicorn Warrior » Wed May 12, 2021 7:35 am

johnnysomersett wrote:
Mon May 10, 2021 1:01 pm
I used to kill a set of modern JJ's about once a year (well, one out of a matched pair) in my old OR120. If they didnt blow within 12 months, I'd change them anyway as part of the yearly service I did on it...just as a precaution. We played at almost full-volume every week at rehearsal, and gigs throughout the year, so they had a tough life. That amp was biased hot, CRANKED and then pushed with a boost/fuzz so I expected it.

Other than that I think I've had a couple of old ones fizzle out randomly over the last 25yrs of owning tube amps. Hardly anything to worry about really.
Can you still hear?

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Re: Talk to me about “burning tubes”

Post by johnnysomersett » Wed May 12, 2021 8:20 am

Unicorn Warrior wrote:
Wed May 12, 2021 7:35 am
johnnysomersett wrote:
Mon May 10, 2021 1:01 pm
I used to kill a set of modern JJ's about once a year (well, one out of a matched pair) in my old OR120. If they didnt blow within 12 months, I'd change them anyway as part of the yearly service I did on it...just as a precaution. We played at almost full-volume every week at rehearsal, and gigs throughout the year, so they had a tough life. That amp was biased hot, CRANKED and then pushed with a boost/fuzz so I expected it.

Other than that I think I've had a couple of old ones fizzle out randomly over the last 25yrs of owning tube amps. Hardly anything to worry about really.
Can you still hear?
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Re: Talk to me about “burning tubes”

Post by jorri » Fri May 14, 2021 2:02 pm

johnnysomersett wrote:
Mon May 10, 2021 1:01 pm
I used to kill a set of modern JJ's about once a year (well, one out of a matched pair) in my old OR120. If they didnt blow within 12 months, I'd change them anyway as part of the yearly service I did on it...just as a precaution. We played at almost full-volume every week at rehearsal, and gigs throughout the year, so they had a tough life. That amp was biased hot, CRANKED and then pushed with a boost/fuzz so I expected it.

Other than that I think I've had a couple of old ones fizzle out randomly over the last 25yrs of owning tube amps. Hardly anything to worry about really.
Is it really just 'modern tubes'?
Well, similar experiences, i used an ac30 in a LOUD band that probably didn't suit an ac30.
I replaced the tubes a few times until it actually was taken to a tech, who put in some NOS tubes and they never got changed again-which was his theory and it 'seemed' to work. I had Harma, EHX, JJ etc. before..
It was hardly every week, but actually during the time i wasn't in a band, basically as low volume as it could it also got through tubes.

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Re: Talk to me about “burning tubes”

Post by Scout » Sat May 15, 2021 7:50 am

Just found this on the local FB, seems to work but it will be my first tube related foray into the wide world of electronics repair.
Image
Cool looking object!

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Re: Talk to me about “burning tubes”

Post by DeathJag » Sat May 15, 2021 10:10 am

COOOOOOOOL!

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Re: Talk to me about “burning tubes”

Post by Unicorn Warrior » Wed May 19, 2021 12:44 pm

Scout wrote:
Sat May 15, 2021 7:50 am
Just found this on the local FB, seems to work but it will be my first tube related foray into the wide world of electronics repair.
Image
Cool looking object!
Yes very cool. I saw one of these at a yard sale once. Not the same brand, but thought about grabbing it although I didn’t own a tube amp at the time

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Re: Talk to me about “burning tubes”

Post by Scout » Wed May 19, 2021 4:42 pm

I couldn't resist. It was cheap and close , it works and I have the room for it.
Back in the day any place that sold tubes had a self service tube tester, It doesn't
do everything but it will kick out a faulty tube.

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