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Post subject: Blues Junior III 1 tube glowing much more than other ?
Posted: Sat May 12, 2012 2:09 pm
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I am new to this forum and I have just bought a new Fender Blues Junior III. After an hour of playing I looked at the back and noticed that one of the tubes was glowing much brighter than the other, is this normal??


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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sat May 12, 2012 3:20 pm
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Nope, Continued use can lead to at least one failure output tube. First thing I'd do, get a can of GOOD contact cleaner (I use Caig DeOxit DN4). Turn off amp. Pull the suspect tube. Use a LITTLE cleaner on its pins and the corresponding socket.

Plug back it. Try the amp. Ok? Cheap fix. But, keep an eye on it. This indicates a wearing socket or bent or oxided tube pin. More attention made be needed, down the road.

If still red after cleaning, you may have the beginings of a shorted tube. Reverse the two output tube postions and see if the red stays with the tube or stays with the socket. Stays with tube = get another matched PAIR. Stays with socket = needs technical work (socket or wiring is bad).


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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sat May 12, 2012 6:57 pm
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BMW, although you are probably correct, the OP never said which tube was glowing bright. :wink:

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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sat May 12, 2012 8:21 pm
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:lol: Never even occured to me that the OP may have been describing gain stage tubes. Perhaps a bit of clarification is needed? Which tubes are we talking about?


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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sun May 13, 2012 1:03 am
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Yes, I forgot to mention. It's got a pair of EL-84 Groove tube output tubes on the far left and three 12AX7 output tubes on the right; the one that's glowing much more than the other is the EL-84 farthest to the left i.e. the first one so to speak? There's also a hum as well?
Many thanks for your responses. Maybe I should just take it back to the store! :cry:


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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sun May 13, 2012 3:00 am
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BMW have the right answer for your EL84


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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sun May 13, 2012 5:52 am
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I've had this happen on another EL-84 amp and it was the tube socket resistor.. Its located on or around the socket. It was failing or never met the proper resistance value. It also messed up the bias.


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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sun May 13, 2012 8:18 am
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akathesauce wrote:
Maybe I should just take it back to the store! :cry:


Brand new amp under warranty, dealer is local to you. Returning it is the best solution. :wink:

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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sun May 13, 2012 11:29 am
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Thanks for the advice. I tried the amp today and guess what? No overly glowing tube, at least no more than the others. Now I'm confused! And no hum either! It seems fine now? :?


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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sun May 13, 2012 11:55 am
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akathesauce wrote:
Thanks for the advice. I tried the amp today and guess what? No overly glowing tube, at least no more than the others. Now I'm confused! And no hum either! It seems fine now? :?


Probably something loose on this tube's socket contact, or resistor with bad solder make intermittent contact.
Or the tube itself ? but IMO more chance problem is in the amp. Tube wich begin to glow won't stop by itself.


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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sun May 13, 2012 1:08 pm
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Well, I cranked it and left her on for over three hours and the offending tube did not glow again like it did on the day I bought it. It would be a shame to have to take it back as I A B tested this against a Blues Junior Red October. I liked this one better, it has a brighter sound ( but that is to be expected ) It's one of the two tones and it looks the dogs dangly bits! Already got a MATAMP Minimat 3 Watt so I didn't need any more of that "British" sound. I want that Fender sparkle.
Thanks for all the posts - this is a great forum. :wink:


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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sun May 13, 2012 1:38 pm
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akathesauce wrote:
I want that Fender sparkle.


Then you need something with 6V6s or 6L6s/5881s. EL-84s are not a traditional Fender sound.

PS:

You should still probably get the amp checked out.

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Last edited by bluesky636 on Sun May 13, 2012 1:44 pm, edited 1 time in total.

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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sun May 13, 2012 1:44 pm
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stratele52 wrote:
Tube wich begin to glow won't stop by itself.


Its amazing how things sometimes do seem to fix themselves, though.

The two nights ago, my amps all developed a nasty ground loop hum. To fix it, I had to set the the ground lift switch on my Radial Big Shot ABY to the opposite position from what it has been for the last 6 months or so. I went through every amp and found nothing that would cause the hum. Last night I turned everything back on and I had to switch the ground lift BACK to where it had always been. Everything has been dead quiet since. Sometimes I think my house is haunted. :lol: :lol: :lol:

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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Sun May 13, 2012 2:17 pm
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If it's new, take it back. :wink:

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Post subject: Re: Blues Junior III 1 tube glowing much more than other ?
Posted: Mon May 14, 2012 7:18 am
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Weekend over and still the offending glow or hum has not returned[url]:shock:[/url]. I'm gonna monitor it and see how it goes. What am I gonna say, the tube glowed once but not doing it now? If it does it again I'm taking it back for sure. Cheers for all the helpful advice.
Darran


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