Help with tube amp problem: Up in smoke - AVS Forum
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post #1 of 7 Old 03-23-2008, 09:02 AM - Thread Starter
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My tube amp (Jolida 102b) has been working well. It is about a year and a half old and the tubes may have about 500 hours on them. I was checking the bias yesterday, which was a bit high, when one of the output amps began to "smoke." It got hot enough to melt some of the graphics/writing off, and now has a surface deformity where it, apparently, melted a bit.

Is this a tube issue, or a larger issue with the amp itself. Is it safe to operate?

Any help is greatly appreciated in advance.

We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology.
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post #2 of 7 Old 03-23-2008, 10:57 AM
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Can't give you much of a detailed answer, but if it began to smoke and now has something partially melted, I'd have it checked out before using it more.

Personally, if you haven't identified for sure what caused it to smoke and repaired that, plus the damage done, I would say it's NOT safe to operate.

Just because there is a knob doesn't mean you should turn it.
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post #3 of 7 Old 03-23-2008, 10:13 PM
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I have a 10year old Jolida 502A amp. have had the 6550C output tubes go, but the fuse cuts power to the amp.NEVER had the amp smoke. I would call your dealer or Jolida in Maryland before turning power back on to the unit.
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post #4 of 7 Old 03-23-2008, 10:21 PM
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NO - it's not safe to operate.

Contact Jolida ASAP and find out what exactly what went wrong.

- Steve O.
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post #5 of 7 Old 03-24-2008, 06:35 AM - Thread Starter
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Thanks, everyone. I pulled the tube out and it looks fine. It did not melt, as I had initially thought. There was something on the surface that, when hot, may have been the source of the smoke: it was pinkish-purple, and looked like nail polish or crayon, and I was able to rub it off. I'll call Jolida and see if they have any thoughts.

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post #6 of 7 Old 03-24-2008, 07:17 AM
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Quote:
Originally Posted by milaz001 View Post

Thanks, everyone. I pulled the tube out and it looks fine. It did not melt, as I had initially thought. There was something on the surface that, when hot, may have been the source of the smoke: it was pinkish-purple, and looked like nail polish or crayon, and I was able to rub it off. I'll call Jolida and see if they have any thoughts.

I thought intially you were talking about one of the output transformers(you said amp, but I'm guessing you meant transformer), not a tube ??? Your first post indicated one of the transformers was smoking, not good, but now your indicating it was a tube ?? let us know what Mike @ Jolida has to say
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post #7 of 7 Old 03-24-2008, 12:03 PM - Thread Starter
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twitch54:

My initial post wasn't clear enough. I was referring to one of the tubes. The (very nice, very helpful) folks at Jolida explained that the only way this could happen was if something was on the tube itself. They feel it's safe to operate.

Thanks so much for everyone's help...

We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology.
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