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Post subject: Blues Junior Volume Drop
Posted: Wed Jan 15, 2014 7:02 pm
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I have a 1 yr old Blues Junior and I swapped the original EL84s for JJs.
I don't know if that has anything to do with it, but recently I've been experiencing volume dropouts as I play at low volume. It fades down to almost nothing then after awhile it comes back up.
I've re-seated all the tubes and checked the speaker connection but the problem persists.
I don't know how much a trip to the shop will cost so I'm hoping to solve this myself if possible.

Thanks for any help.


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Post subject: Re: Blues Junior Volume Drop
Posted: Wed Jan 15, 2014 7:40 pm
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Mister Mxyzptlk, welcome to the Forum! :D


Did you have the idle bias checked, after installing the new JJ EL84's?


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Post subject: Re: Blues Junior Volume Drop
Posted: Wed Jan 15, 2014 7:43 pm
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No. I just swapped the tubes out.


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Post subject: Re: Blues Junior Volume Drop
Posted: Wed Jan 15, 2014 11:14 pm
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Perhaps the newly replaced EL84 are running too hot. If they are biased ok (need to be checked by tech) --- you could have some instability going on between the amp and the new tubes.

If you put the old tubes back in, does the amp still cut-out?


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Post subject: Re: Blues Junior Volume Drop
Posted: Thu Jan 16, 2014 2:24 am
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You may have a defective new EL84 tube.

Follow BMW2002Ti advice, put olds ones to check .


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Post subject: Re: Blues Junior Volume Drop
Posted: Thu Jan 16, 2014 4:06 pm
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Thanks to everyone :)

Originally, I swapped the original Groove Tubes for the JJs because I thought I had a defective tube since I was getting no sound.
As it turned out, the speaker had somehow disconnected because the power cord bumped into it in transit.
After swapping to the JJs, I discovered what the real problem was and fixed that easily.
Then I just left the JJs in because of their reputation.

I will try the original tubes soon and report back.

Thanks again.


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Post subject: Re: Blues Junior Volume Drop
Posted: Thu Jan 16, 2014 4:15 pm
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Well, not good news.

After putting the original GTs back in, the volume was down (not completely, but pretty low) and there was a slight smell coming from the amp.

So what then, having the JJs in there somehow possibly damaged the amp?
If you buy a pair of EL84s they shouldn't they work immediately without any adjustments requiring a service technician?


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Post subject: Re: Blues Junior Volume Drop
Posted: Thu Jan 16, 2014 5:04 pm
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Mister Mxyzptlk wrote:

If you buy a pair of EL84s they shouldn't they work immediately without any adjustments requiring a service technician?



No. Output Power tubes always need a bias check and adjust . Sometimes no if you buy exactly the same brand


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Post subject: Re: Blues Junior Volume Drop
Posted: Thu Jan 16, 2014 5:05 pm
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Mister Mxyzptlk wrote:
Well, not good news.

After putting the original GTs back in, the volume was down (not completely, but pretty low) and there was a slight smell coming from the amp.
You have to open the amp and see if any resistor is burn or someting else



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Post subject: Re: Blues Junior Volume Drop
Posted: Thu Jan 16, 2014 5:19 pm
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Thanks, looks like a trip to the shop then. :(


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Post subject: Re: Blues Junior Volume Drop
Posted: Thu Jan 16, 2014 5:33 pm
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Mister Mxyzptlk wrote:
Thanks, looks like a trip to the shop then. :(


Be sure you see a qualified tech if you don't whant to loose money . There are not so many qualified tech .


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